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Assessment of food intakes for women adopting the high protein Dukan diet

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  • University of Applied Sciences in Nysa, Poland Państwowa Wyższa Szkoła Zawodowa w Nysie, Polska

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Background: Overweight and obesity are metabolic disorders affecting both adults and children. Effective treatment of these conditions is focused on decreasing the body mass, through individually tailored and well balanced diets, along with increasing physical activity. Obese persons often, however, choose high protein diets for losing weight. Recently in Poland, the high-protein Dukan-diet has become very popular. Objectives: To assess dietary consumption in women adopting the Dukan-diet, including intakes of protein, fat, carbohydrate as well as vitamins and minerals. Materials and methods: Subjects were 51 women aged 19-64 years on the Dukan-diet, who were surveyed by individually conducted interview. Women were asked to provide typical menus from each phase of their diets. Quantitative dietary intake assessment was achieved by an officially used 'Photograph album of foodstuffs and dishes' as custom-designed by the National Food and Nutrition Institute (IZZ) in Warsaw. Results: Protein intakes in all subjects were excessive, especially those of animal origin when compared to recommended nutritional standards. In contrast, dietary carbohydrate intakes were low due to poor consumption of fruit and vegetables. Mineral and vitamin intakes revealed high potassium, iron and vitamins A, D and B2, but low vitamin C and folates. Women's average weight reduction after 8-10 weeks of dieting was approximately 15 kilograms. Conclusions: Many nutritional abnormalities were found in women on the high protein Dukan-diet. Adopting this diet in the long-term may pose health threats through acquiring kidney and liver disease, osteoporosis and cardiovascular disease. Key words: obesity, high protein diet, nutrients.
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Rocz Panstw Zakl Hig 2015;66(2):137-142
*Corresponding author: Joanna Wyka, Institute of Dietetics, University of Applied Sciences in Nysa, Ujejskiego street 12,
48-300 Nysa, Poland, phone +48 77 409 16 52, e-mail: joanna.wyka@pwsz.nysa.pl
© Copyright by the National Institute of Public Health - National Institute of Hygiene
ASSESSMENT OF FOOD INTAKES FOR WOMEN ADOPTING
THE HIGH PROTEIN DUKAN DIET
Joanna Wyka*, Ewa Malczyk, Marta Misiarz, Marzena Zołoteńka-Synowiec,
Beata Całyniuk, Sandra Baczyńska
Institute of Dietetics, University of Applied Sciences in Nysa, Ujejskiego street 12, 48-300 Nysa, Poland
ABSTRACT
Background. Overweight and obesity are metabolic disorders affecting both adults and children. Effective treatment of
these conditions is focused on decreasing the body mass, through individually tailored and well balanced diets, along with
increasing physical activity. Obese persons often, however, choose high protein diets for losing weight. Recently in Poland,
the high-protein Dukan-diet has become very popular.
Objectives. To assess dietary consumption in women adopting the Dukan-diet, including intakes of protein, fat, carbohy-
drate as well as vitamins and minerals.
Materials and Methods. Subjects were 51 women aged 19-64 years on the Dukan-diet, who were surveyed by individu-
ally conducted interview. Women were asked to provide typical menus from each phase of their diets. Quantitative dietary
intake assessment was achieved by an officially used ‘Photograph album of foodstuffs and dishes’ as custom-designed by
the National Food and Nutrition Institute (IZZ) in Warsaw.
Results. Protein intakes in all subjects were excessive, especially those of animal origin when compared to recommended
nutritional standards. In contrast, dietary carbohydrate intakes were low due to poor consumption of fruit and vegetables.
Mineral and vitamin intakes revealed high potassium, iron and vitamins A, D and B2, but low vitamin C and folates. Women’s
average weight reduction after 8-10 weeks of dieting was approximately 15 kilograms.
Conclusions. Many nutritional abnormalities were found in women on the high protein Dukan-diet. Adopting this diet in
the long-term may pose health threats through acquiring kidney and liver disease, osteoporosis and cardiovascular disease.
Key words: obesity, high protein diet, nutrients
STRESZCZENIE
Wprowadzenie. Otyłość i nadwaga są chorobami metabolicznymi, które dotyczą zarówno dorosłych, jak i dzieci. Właści-
wym postępowaniem w leczeniu tych chorób jest zmniejszenie masy ciała poprzez zastosowanie indywidualnej, dobrze
zbilansowanej diety oraz zwiększenie aktywności fizycznej. W celu redukcji masy ciała otyli pacjenci czasami decydują się
na zastosowanie diety wysokobiałkowej. W Polsce, w ostatnich latach, bardzo popularna jest wysokobiałkowa dieta Dukana.
Cel. Celem badań była ocena sposobu żywienia kobiet stosujących dietę wysokobiałkową Dukana. Oceniono zawartość
białek, tłuszczów, węglowodanów, a także witamin i składników mineralnych w diecie badanych kobiet.
Materiały i metody. Badanie zostało przeprowadzone za pomocą 24-godzinnego wywiadu przeprowadzonego indywidualnie
z każdą respondentką. W badaniu wzięło udział 51 kobiet w wieku 19-64 lat stosujących wysokobiałkową dietę Dukana.
Kobiety poproszono o podanie przykładowego jadłospisu z każdej fazy diety. Do oszacowania w wielkości (w gramach)
spożytej żywności wykorzystano „Album fotografii produktów i potraw” opracowany przez Instytut Żywności i Żywienia
w Warszawie.
Wyniki. Kobiety biorące udział w badaniu spożywały nadmierną ilość białka, szczególnie pochodzenia zwierzęcego,
w stosunku do zalecanych norm żywieniowych. Zawartość węglowodanów w racjach pokarmowych była niska i wynikała
z małej podaży warzyw i owoców. Wśród ocenianych składników mineralnych stwierdzono najniższe spożycie potasu
i żelaza, a najwyższe fosforu i sodu. Wykazano także, że ze stosowaną dietą niska była podaż witaminy C i folianów, na-
tomiast wysoka witamin A, D i B2. Wśród badanych kobiet, średnia redukcja masy ciała po 8-10 tygodniach stosowania
diety wynosiła około 15 kilogramów.
Wnioski. U kobiet stosujących wysokobiałkową dietę Dukana stwierdzono wiele nieprawidłowości żywieniowych. Długo-
trwałe stosowanie tej diety może zwiększyć ryzyko zdrowotne związane z wystąpieniem chorób nerek i wątroby, osteoporozy
oraz chorób sercowo-naczyniowych.
Słowa kluczowe: otyłość, dieta wysokobiałkowa, składniki odżywcze
J. Wyka, E. Malczyk, M. Misiarz, et al.
138 No 2
INTRODUCTION
Overweight and obesity are metabolic diseases
which are an ever rising problem in Poland as well as
the majority of economically developed countries of the
world. The WOBASZ study on overweight and obesity
undertaken in Poland, has shown these symptoms in
61.6% men and 50.3% women [1]. Above all, these were
found to arise from excess calorific dietary intake rela-
tive to its utilization [2]. Effective treatment of obesity
requires long-term therapy and a cooperation between
the patient with a multi-disciplinary team of dietician,
doctor, psychologist, physiotherapist and personal tra-
iner. The therapy is based on a multi-tier education of
the obese person, together with an individualised and
well balanced diet having a negative energy balance [21,
34]. Patience and being consistent are traits needed for
keeping to such diets. Obese patients however, usually
wish for quick results in losing weight and they have
often also tried slimming on several previous occasions
– without any lasting success.
Diets of varying nutrient content have become
popular in recent times, of which the most well known
are the single component types, with a preponderance
of protein [4, 6, 8]. The popularity of high protein diets
(i.e. >25% of protein derived calories) are because of
their rapid effects and no limits placed on how much
high protein foodstuffs are to be consumed [5]. Such
diets, where high protein is coupled to low carbohy-
drate, lead to rapid weight loss where, amongst other
things, this is caused by having reduced ghrelin levels;
a hormone produced by gastric parietal cells responsible
for reducing hunger pangs. Ghrelin concentrations de-
crease mainly due to dietary carbohydrate deficiencies,
followed by protein then fats. A carbohydrate-poor diet
leads to dehydration, where together with the utiliza-
tion of glycogen stores from muscle and liver, water is
removed from the body at a rate of 2-3 g water per 1 g
glycogen [3, 10, 22, 27].
Within the Polish scientific literature, not much data
has been gathered on the health impact of the long term
adoption of either high protein or high fat diets intended
for losing body mass [2, 20]. Results from the rest of
the world are from short-term studies that indicate a
clear body weight loss arising from low calorie diets,
vitamin and mineral intake deficiencies as well as in
renal function disorders due to increased glomerular
filtration of toxic products from nitrogen metabolism
[16, 32]. The long-term adoption of high protein diets
may lead to hyper-filtration, glomerular overload and
proteinuria. Filtered protein damages renal tubules
and upon entering the interstitial tissue, inflammation
results. Likewise, a diet containing processed meat
products, rich in protein, delivers excessive phosphates
leading to the development of secondary hyperthyro-
idism. Furthermore, a high protein diet causes increased
metabolic acidosis, a characteristic of advanced renal
failure [13, 15, 17, 28].
The study aim was to perform a dietary assessment
of those women on a high protein Dukan-diet, based on
surveying their menus from each of the diet’s 4 phases.
MATERIALS AND METHODS
The study surveyed 51 women subjects aged 19-64
years, that were on the Dukan-diet with no limits placed
for food consumption. The ‘Snowball Sampling’ method
was used for their recruitment i.e. a non-random sam-
ple selection dependent on existing subjects recruiting
others of their acquaintance [26, 29]. An assessment was
performed by individual interview for each subject on
the nutrition over the last 24 hours.
Table 1. Energy and nutrients in diet of women adopting the high protein Dukan diet according to the diet’s phase
Calories and
nutrient content
Phase I Phase II Phase III Phase IV
x ±SD (% of standards)
Calories [kcal] 888.0±558.0 (44.4%) 1020.0±303.7 (51%) 1014.0 ±407.0 (50.7%) 1008.0 ±482.0 (50.4%)
Protein [g] 109.0 ±18.2 (167.6%) 116.0 ±15.6 (178.4%) 87.0 ±14.8 (133.8%) 114.0 ±13.6 (175.3%)
Fat [g] 34.7 ±27.2 (51.0%) 33.3 ±16.3 (50,0%) 60.9 ±21.0 (92.2%) 48.7 ±19.6 (72.7%)
Carbohydrate [g] 39.7 ±17.8 (13.6%) 70.3 ±25.8 (24.5%) 30.8 ±15.6 (10.5%) 30.7 ±17.8 (10.7%)
Minerals
Calcium [mg] 675.0 ±256.0 (67.5%) 1003.0 ±311.0 (100.0%) 860.0 ±311.0 (86.0%) 954.0 ±372.0 (95.0%)
Iron [mg] 7.8 ±2.4 (43.3%) 11.7 ±3.8 (65.0%) 9.3 ±3.1 (51.6%) 5.3 ±1.4 (29.4%)
Sodium [mg] 1751.0 ±572.0 (116.0%) 1862.0 ±422.0 (124.1%) 1392.0 ±379.0 (92.8%) 1698.0 ±497.0 (113.2%)
Potassium [mg] 2129.0 ±645.0 (45.2%) 3464.0 ±582.0 (73.0%) 2911.0 ±602.0 (61,9%) 2335.0 ±645.0 (49.6%)
Phosphorus [mg] 1670.0 ±207.0 (238.5%) 1312.0 ±197.0 (187.4%) 1526.0 ±251.0 (218.0%) 1706.0 ±232.0 (243.0%)
Vitamins
A [µg] 1386.0 ±158.0 (198.0%) 1383.0 ±563.0 (197.0%) 1523.0 ±488.0 (217.0%) 1331.0 ±165.0 (190.0%)
D [µg] 7.6 ±3.5 (152.0%) 5.9±2.5 (118.0%) 5.5±2.0 (110.0%) 6.3±3.7 (126.0%)
B2 [mg] 2.0±0.5 (181.0%) 2.6±0.7 (236.0%) 1.9±0.6 (172.0%) 2.1±0.7 (190.0%)
C [mg] 2.7±1.7 (3.6%) 4.5±2.6 (6.0%) 2.5±1.9 (3.3%) 3.9±2.3 (5.2%)
Folate [µg] 120.0±53.0 (30.0%) 105.0±43.0 (26.2%) 155.0±62.0 (38.7%) 99.0±39.0 (24.7%)
Food intakes for women adopting the high protein Dukan diet 139No 2
Women subjects were asked to provide a typical
daily menu from the I, II, III and IV phases of their diet.
In phase I they consumed high protein foodstuffs, whilst
in the ensuing phases, other products could also be
introduced; in phase II some vegetables were allowed,
phase III some fruit and starch products whilst phase IV
only permitted high protein foodstuffs with a so called
‘pure protein day’ once per week. Quantitative dietary
intakes were determined by using the aforementioned
‘Photograph album of foodstuffs and dishes’ as custom-
-designed by the IZZ in Warsaw [30].
Menus were evaluated by the ‘Dieta 5’ computer
programme using a data base compiled by Kunachowicz
et al., also from the IZZ [14]. Additional information
was gathered on body mass and height before, during
and after dieting. The diet’s calorific value and nutrient
content were compared to recommended Polish nutritio-
nal standards [11] for each subject. From these, calorific
values were taken as those appropriate to the body mass
of each subject when there are low levels of physical
activity and assuming that dietary calories are derived
from 13% protein, 30% fat and 57% carbohydrate.
Dietary vitamin and mineral values were also compared
to either the Recommended Daily Allowance (RDA) or
the Adequate Intake (AI) for adult women.
Table 1 presents the mean dietary calorific and
macronutrient content (i.e. protein, fat and carbohy-
drate) along with minerals (calcium, iron, potassium
and phosphorus) and vitamins (A, D, B2, C and folates)
during each phase of the Dukan diet and the proportion
that this covers the recommended standards. Mean
dietary calories derived from each macronutrient (i.e.
protein, fat and carbohydrate), for the average diet of
each subject were compared to those recommended
by the IZZ. The subjects were broken down into 3 age
groups as follows; 40% aged 19-30 years, 47% aged 31
to 51 years and 13% aged 51-64%. Before dieting, the
BMI could be grouped into the following ranges; 47%
women (25-29.9), 47% (30-34.9) - 1st degree obesity,
and 6% (35-39.9) 2nd degree obesity.
RESULTS
For the phase I, high protein diet, the mean dietary
calorific values were 888.0 kcal (Table 1) which cove-
red the recommended standards for each subject by an
average of 44.4%, whilst mean protein intakes were 109
g making up a mean of 167.7% to the recommended
standards. Mean dietary fat intakes of 34.7 g covered
these standards by 51% and those for carbohydrates
were respectively 39.7 g and only 13.6%. Calcium
intake made up 67.5% of the recommendations. The
mean body mass loss during phase I was 2.4 kg. In the
following phases, similar nutrient contents were obse-
rved. Phase III showed intakes of 87 g protein and 60
g fat which are closer to standards set. Because of the
diet’s low calorific value (1014 kcal), the proportion
of calories in this phase that is derived from specific
nutrients differs most from the WHO/IZZ recommen-
dations (Figure 1). Calories derived from protein, fat
and carbohydrate during phase III are respectively 34%,
54% and 12% (Figure 1). In phase II, the highest body
mass reduction was found; on average by 10.6 kg. The
dietary intakes in phase IV demonstrated the greatest
iron and potassium deficiencies of respectively 29.4%
and 49.6% to the standards as well as having the highest
excess of phosphorus that covered 243.0% of standards.
Dietary intakes of vitamin C and folates were very low
in all phases; being respectively 3-6% and 24-38% of the
standards. During dieting after 8-10 weeks, the average
body mass loss was by around 15.0 kg.
Figure 1. Dietary calories derived from protein, fat and carbohydrate for women adopting a
high protein diet according to the diet’s phase
Dietary phases
% energy from macronutriens
Figure 1. Dietary calories derived from protein, fat and carbohydrate for women adopting a high protein diet according to
the diet’s phase
J. Wyka, E. Malczyk, M. Misiarz, et al.
140 No 2
DISCUSSION
Despite introducing preventative and therapeutic
programmes of education that deal with obesity each
year to the general public worldwide, attempts to global-
ly reduce the adverse increases in body mass have pro-
ved ineffective. Additionally, obesity is recognised to be
a risk factor in many other metabolic diseases, together
with hypertension, diabetes and cardiovascular disease;
all falling into the category of the Metabolic Syndrome
(MS). Obesity requires long-term treatment, which at
present focuses on lifestyle and genotype, but equally
also extra-nutritional factors such as economic-social
status, education and mental health. The effectiveness
of a rational and safe reductive diet, as recommended
by WHO/IZZ, is conditional on consistently and thoro-
ughly keeping to its principles. Patients however expect
quick outcomes, which directly serves to motivate
them in seeking unconventional and fashionable diets.
Nonetheless, very few are aware of the adverse health
effects in adopting such dieting.
By reducing carbohydrate intakes, high-calorie
foodstuffs become excluded, like pizza, pasta or bread
thereby decreasing a diet’s calories by around 500 kcal.
Limiting dietary energy intake forms the basis of all
slimming diets, as does having a normally balanced
diet to achieve body mass loss. During deficiencies in
dietary carbohydrate intake, free fatty acids are meta-
bolised from which ketone bodies arise. Ketosis status
is an important factor for inhibiting appetite [6]. In
the first days of adopting the diet, various processes
occur leading to the body losing water, such as glyco-
gen mobilisation from muscle or the liver; a glycogen
loss of 400 g reduces water by 1 kg. Another cause of
dehydration is the excretion of ketone bodies in the
urine. Adopting a high protein diet carries the potential
risk for elevated serum homocysteine concentrations,
which is a sulphur containing amino acid produced by
methionine metabolism present in animal meat protein.
For homocysteine to become adequately metabolised,
then vitamin B group vitamins and folates are required
in sufficient amounts; as delivered through the diet.
Dietary deficiencies of these vitamins are observed in
women adopting high protein diets leading to blood
vessel damage and may result in arteriosclerosis [25].
Studies on healthy subjects eating high protein diets
have been unable to show any disorders in glomerular
filtration. Nevertheless, an increased excretion of cal-
cium, urates and phosphates was observed which may
lead to kidney stone formation [12, 24]. Disturbing the
acid-base balance, as a result of high dietary protein
intake, also increases the risk of osteoporosis [19, 33].
Excessive consumption of animal derived protein, being
a rich source of purines, increases serum concentrations
of uric acid, that leads to hypertension and renal function
disorders. The advantages of rapid weight loss of high
protein diets needs to be reconciled with the potential
health threats such as advancing renal and cardiovascu-
lar disease. Extensive recent studies have compared the
effectiveness for reducing body mass by adopting diets
supplying various macronutrients [7].
In summary, the authors stress that the greatest body
mass loss was seen after 6 months of adopting each diet
(arising from a decreased calorie intake) amounting to
around 6 kg. Following 2 years of following a 15% or
25% protein diet, the loss of body mass were respec-
tively 3 and 3.6 kg. An approximate 3.3 kg body mass
loss was observed in those adopting a 20% and 40%
fat diet, whilst subjects on 65% and 35% carbohydrate
diets lost respectively 2.9 kg and 3.4 kg. When discus-
sing the dietary role of protein, Te Morenga and Mann
[31] emphasised that body mass loss in those obese
subjects adopting high protein diets arises from reduced
calorific intakes. Taking up such eating habits may lead
to an increased cancer risk through excessive red meat
consumption as well as lowering blood pressure and
evening-out the blood lipid profile.
The presented study demonstrated a reduced risk of
contracting diabetes for those taking up a high protein
diet through improved glycaemic control and insulin
resistance. Following a 55-60% carbohydrate diet with
15% protein or a 40-45% carbohydrate diet with 25-30%
protein together with taking physical exercise, led to the
following to become lowered; insulin resistance index
by 0.2, BMI by 6.8% and body adipose tissue in studied
teenagers by 2.4%. When comparing the health benefits
of adopting high carbohydrate, protein and fat diets in 96
women subjects (BMI<27), McAuley et al. [18] found
that, after 8 weeks, all 3 diets caused body mass loss,
reduced waistline and decreased serum triglycerides.
Blood insulin was significantly reduced in women
following high protein and high fat diets compared to
those adopting a high carbohydrate diet.
CONCLUSIONS
1. Women taking up high protein diets demonstrated
deficient calorific intake which was responsible for
the lowering of body mass.
2. The women’s diet had low contents of carbohydrate,
calcium, iron, potassium, vitamin C and folates but
excessive amounts of protein, phosphorus, sodium
along with vitamins A and D.
3. Adopting a high protein diet in the long term may
be harmful to health.
Conflict of interest
The authors declare no conflict of interest.
Food intakes for women adopting the high protein Dukan diet 141No 2
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... Rats were kept in cages in groups of five with free access to food and water in rooms with a temperature of 22 ± 2 o C and seasonal daylight rhythm. 40 [15,29]. After the rats reached puberty, vaginal smear samples were taken daily to study the estrous cycle pattern. ...
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To date, there is no comparative data on the effects of carbohydrates, fat, and proteins, which are macronutrients, on female reproductive functions. Therefore, in this study, we investigated the effects of diets enriched with carbohydrates, fats, and proteins on folliculogenesis and oocyte development in female rats. 21-day-old rats that were just weaned were divided into 4 groups: control, carbohydrate, fat, and protein. The control group was fed with standard chow and the carbohydrate, fat, and protein groups were fed diets enriched with 75% carbohydrate, 60% fat, and 50% protein for 11 weeks, respectively. It was found that high-fat and high-protein diets caused an increase in the estrous cycle length compared to carbohydrate group ( p < 0.05). Graafian follicle number decreased in the protein group compared to the control ( p < 0.05). However, the atretic follicle number was higher in the fat group compared to the control group ( p < 0.05). In the carbohydrate group, Zp1 was found to be lower than the control and protein groups, Zp2 was found to be lower than the control, and Zp3 was found to be lower than the fat group ( p < 0.05). While BMP15 was similar between groups ( p > 0.05), GDF9 was lower in all diet groups compared to the control ( p < 0.05). Foxo3a was lower in the protein group compared to carbohydrate and control ( p < 0.05). GAS2 was found to be higher in the control group than the fat group, and higher in the carbohydrate group than the fat and protein groups ( p < 0.05). FSH, LH, Progesterone, and E2 levels were higher in all three diet groups than in the control ( p < 0.05). Also, significant differences were observed between the groups regarding adiponectin, resistin, and leptin levels. Taken together, high carbohydrate, fat, and protein intake are associated with impairment of the menstrual cycle, depletion of the developing follicle types, and altered expression of folliculogenesis-specific genes and hormones. Therefore, long-term macronutrient diets may result in shortened reproductive periods and reduced fertilization potential in females in the long run.
... This category grouped 15 out of 179 studied diets, the Dukan diet being the most widely recognized. Wyka et al. [95] suggested that long-term following this diet could pose health threats. They specifically mentioned the potential risks of acquiring kidney and liver disease, osteoporosis, and cardiovascular disease. ...
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The relationship between obesity and weight loss treatments has run parallel throughout history; however, not all diets are suitable for improving one’s health. This review aims to categorize diets according to the new classification of hazardous diets established in 2021. A search was conducted across grey, white, and black literature. The results reveal a study of 179 diets, of which 35 are effective, while the rest are hazardous to health. Looking at the geographical distribution of these diets, the USA, the UK, and Greece dominate the top three spots. The geographic distribution of diets is linked to cultural and environmental factors, with influencers often playing a predominant role. Additionally, the lack of legislative oversight on emerging diets is a noteworthy concern, highlighting the need for regulatory measures to ensure the safety and well-being of individuals engaging in such dietary practices. Regarding the creators of these weight loss treatments, it is noteworthy that only 7.8% are nutrition specialists, all of whom fall under the effective diets category. This demonstrates that healthy treatments and nutritionists are the best combination for losing weight and improving health.
... Individuals suffering from illnesses such as type 2 diabetes or metabolic syndrome may benefit from this. The diet's emphasis on protein and restricted carbohydrates may help stabilize blood sugar levels, which could assist people with diabetes or those who are prone to blood sugar imbalances [77]. ...
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Maintaining a well-balanced diet and considering how to fulfill all the adequate nutrition required by the body will help us live a healthy lifestyle. The risk of illness, infection, exhaustion, and poor performance increases when a balanced diet is absent. The anti-treatment technique of food modification has gained a lot of attention in research over the past few decades. Popular diets include Mediterranean, vegan, and low-carbohydrate diets. The vegan diet is a plant-based eating plan that eliminates animal products and emphasizes fruits, vegetables, legumes, whole grains, nuts, and seeds. The Palaeolithic age diet emphasizes eating full, unprocessed foods available to early people while avoiding grains, legumes, dairy products, refined sugar, and processed foods. Proponents claim it can improve health, and aid in weight loss. Numerous dietary patterns, such as caloric restriction (CR), dietary approaches to stop hypertension (DASH), ketogenic diets (KD), the Mediterranean diet (Medi), and Mediterranean-DASH diet Intervention for Neurological Delay (MIND) diet, have been tried to reduce body weight, any other disease infections, and cognitive decline. Increased Mediterranean diet adherence was linked to reductions in cardiovascular and neurological conditions, including Alzheimer's disease (AD) and related cognitive loss. The MIND diet, a new good dietary pattern has been linked to a significantly lower incidence of AD and slower rates of cognitive deterioration. The current piece of work emphasizes the introduction, nutritional components, and health advantages of different types of diet.
... They suggest that this diet may be harmful to health if adopted for a long time, developing of kidney and liver disease, osteoporosis and cardiovascular disease. 12 Considering that the Dukan Diet is widely disseminated and it is used by the population in general for weight loss and few scientific studies are found in the literature, we propose to evaluate the nutritional, laboratory parameters related to cardiovascular disease, comparing this diet with traditional hypocaloric diet in obese individuals. ...
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Background and Aims: Dukan diet, a popular diet with high content of protein and carbohydrate and fat restriction has been widely used for weight loss. We aimed to compare the effects of the Dukan diet with traditional low-calorie diet in nutritional, laboratory and vascular parameters in obese subjects. Methods and Results: Obese subjects classes I or II of both genders, aging 19 to 65 years were allocated into two groups: Traditional low-calorie diet (n=17) and Dukan Diet (n=17). Anthropometric, laboratory and vascular evaluations were performed at baseline, 3, 6 and 12 months. Body composition was evaluated by bioelectric impedance and endothelial function by flow-mediated dilation of the brachial artery, at same times. After 12 months, it was verified that Dukan diet was more effective (p<0.05) than traditional diet for: weight loss (-10.6 vs -2.9 kg), body mass index (-3.7 vs -1.1 kg/m2), waist circumference (-11.2 vs -2.1 cm), fat (-5.7 vs -2.0 kg) and lean mass (-4.8 vs 0.8 kg) and basal metabolic rate (-152 vs -28 cal). In Dukan diet group, improvement (p<0.05 vs baseline) was observed in triglyceride levels (172.40 to 111.90 mg/dL) and insulin resistance, based on HOMA-IR index (4.98 to 3.26). The glomerular filtration rate decreased in this group after 3 months (132.50 to 113.80 mL/min) and no changes in flow-mediated dilation were observed throughout the study with both diets. Conclusion: Dukan diet was more effective than traditional diet for weight loss and laboratory parameters and without changes in endothelial function, in the 12-months follow-up of obese subjects. Introduction Low-carbohydrate diets have been one of the most recently used dietary therapies in patients with diabetes and obesity in clinical studies(1). Among them, in addition to carbohydrate restriction, fat restriction and high protein concentration, as in the Diet Dukan, has been widely used by the general population, aiming at weight loss. The Dukan diet is designed to reduce carbohydrate and fat intake in the first phase of the diet, with exclusive intake of protein, followed by another Three phases, with progressive and slow reintroduction of other nutrients such as fiber, carbohydrates and fats. In recent years, there has been increasing interest in the effectiveness of very low carbohydrate diets, called ketogenic diets, in the effectiveness of weight loss in order to combat obesity and cardiovascular disease risk(2). In this diet, ketone bodies are formed and they are used as an alternative energy source in the absence of glucose. Ketogenic diet promotes weight loss reducing appetite, increasing satiety and thermogenesis, due to the high protein consumption(3) affect hormones that control appetite, such as ghrelin and leptin(4) reduces lipogenesis and increases lipolysis(5,6) and gluconeogenesis(7). Replacing carbohydrates by proteins in the diet have been the aim of several studies but with inconsistent results. High protein intake has positive effects on weight loss, acting on satiety, body composition, lipid profile and glucose homeostasis. Furthermore, it increases thermogenesis, energy expenditure(8) and the elevation in the amino acid level in the plasma acts on the satiety center, decreasing appetite, since amino acids also stimulate insulin secretion resulting in decreased or maintained blood glucose levels(9). Few studies have been published with Dukan diet. Freeman et al. were the first to publish an article with the Dukan Diet in 2014, describing adverse effects in one patient undergoing this diet(10). Nouvenne et al. reviewed studies about the influence of popular diets on kidney stone formation risk. In this article, the authors suggest that in the Dukan diet, due to the high consumption of animal protein, urinary calcium can increase and the citrate urinary excretion can decrease, increasing the risk of kidney stone formation(11). In 2015, Wyka et al. evaluated dietary consumption in women adopting the Dukan-diet, based on the menu consumed in each of 4 phases of diet. They observed weight loss of around 15 kg after 8 to 10 weeks of diet and higher intake of proteins, mainly of animal origin, high consumption of potassium, iron and vitamins A, D and B2 and reduced consumption of carbohydrates, vitamin C and folates. They suggest that this diet may be harmful to health if adopted for a long time, developing of kidney and liver disease, osteoporosis and cardiovascular disease(12). Considering that the Dukan Diet is widely disseminated and it is used by the population in general for weight loss and few scientific studies are found in the literature, we propose to evaluate the nutritional, laboratory parameters related to cardiovascular disease, comparing this diet with traditional hypocaloric diet in obese individuals. Methods Study design This study was a clinical trial with nutritional intervention, for one year. Patients were recruited from the Lipids, Atherosclerosis and Vascular Biology Division of the Universidade Federal de São Paulo (UNIFESP). The study conforms to the ethical guidelines and approval was obtained from the ethics committee and it was registered in the Brazilian Registry of Clinical Trials. All participants provided written informed consent and received no monetary incentive. A total of 40 subjects were initially recruited and the participants were followed up clinically by a cardiologist and nutritionist during the 12-month period with monthly visits. Of the 40 participants who started the study, 34 completed the 12-month follow-up, whose data are presented in this study. The inclusion criteria were: both genders, aging 19-65 years old, obesity grade I or II (body mass index between 30 kg/m² and 39.9 kg/m²), stable body weight in the previous 3 months and desire to lose weight. The main exclusion criteria were: patients in primary or secondary prevention of coronary heart disease with low-density lipoprotein cholesterol (LDL-C) levels greater than 190 mg/dL and triglycerides greater than 400 mg/dL; diabetes mellitus; untreated hypothyroidism; psychiatric and hepatic disease; chronic renal failure; cardiac and respiratory insufficiency; systemic infections; use of antidepressants, corticoids, diuretics and diabetes medications; bariatric surgery, cancer and failure to accept the conditions necessary to conduct the research. Two groups were constituted: Traditional low-calorie diet (TD): n=17, 14 females and 3 males, 45±11 years old, 90±11 Kg body weight and body mass index (BMI) 34±2Kg/m2; High protein/Low carbohydrate diet-Dukan Diet (DD): n=17, 10 females and 7 males, 38±11 years old, 95±9 Kg of body weight and BMI 34±2 Kg/m2. The TD group received orientations according to the Food Guideline for the Brazilian Population, with 1 500–1 800 calories/day. They were stimulated to improve healthy eating habits increasing the consumption of natural foods without preservatives, such as vegetables and fruits rich in fiber and antioxidants. Daily consumption of fruits and vegetables at meals was recommended; carry out the fractionation of the meals throughout the day, avoiding prolonged fasting. Hydration and regular physical activity were recommended, according to healthier life habits(13). The DD group followed the high-protein/low-carbohydrate diet as proposed by Dukan Diet, available at https://www.dietadukan.com.br and received an illustrated book about this diet(14). This diet is structured in four phases: two for weight loss (1st and 2nd phases) and two for weight maintenance (3rd and 4th phases): 1st stage - Attack: For 5 consecutive days, it is allowed to consume only proteins with lean meats, eggs, light cheese and milk, 1.5 tablespoons of oat bran per day and light physical activity for 20 minutes. 2nd stage - Cruise: This phase is maintained until the desired weight loss. The vegetables are introduced alternating with the pure protein day (first stage). It is recommended 2 tablespoons of oat bran per day and light physical activity for 30 minutes. 3rd phase - Consolidation: The time of this phase is equivalent to 10 days per kg of lost weight. In this stage carbohydrates and lipids are introduced by a controlled and moderate way, being divided in two parts: in the first part, corresponding to half of the period to be followed, is allowed: 1 fruit, 2 slices of bread (50 g) or 1 spoon of farinaceous per day and 1 gala dinner per week. In the second part, it is allowed 2 fruits, 4 slices of bread (100 g) or 2 spoons of farinaceous per day and 2 gala dinners per week. This phase has one rule: make one day of the week with pure protein (first stage) and it is recommended 2.5 tablespoons of oat bran per day and light physical activity for 35 minutes. 4th phase - Stabilization: In this phase, three rules must to be followed: one day a week it should follow up the pure protein diet, the daily consumption of 3 tablespoons of oat bran and at least 40 minutes of daily walking. From this phase, the participants followed up the low calorie diet. The adherence of the participants was monitored by the interview with the nutritionist and qualitative evaluation of ketone bodies in the urine, using Labtest UriAction 10 reagent strips. At baseline, 3, 6 and 12 months, the following evaluations were performed: nutritional assessment determining anthropometry, blood samples were collected for laboratory tests. Endothelial function was evaluated in fasting and 2-hours post prandial situations. In the periods between the predetermined visits, the participants were followed up by the nutritionist monthly and by telephone contact whenever requested and with medical attention whenever necessary. Nutritional evaluation Nutritional assessment was performed by anthropometric determinations of weight, height, BMI, abdominal circumference and bioelectric impedance (BIA). BIA was carried out using the Biodynamics Model 450 TBW® apparatus, with portable plethysmograph and patients were instructed according to the manufacturer's instruction(15). Laboratory parameters Peripheral blood samples were collected for dosages of total cholesterol and fractions, triglycerides, glucoses, insulin, iron, ferritin, ALT, AST, urea, creatinine, hemoglobin and hematocrit. Biochemical parameters were determined through the automated colorimetric enzymatic method in Cobas Mira® (Roche, Switzerland) and LDL-c was estimated by the Friedewald equation. Serum insulin concentration was determined by immunofluorometry and the insulin resistance calculated by the HOMA-IR – Homeostasis Model Assessment Insulin Resistance, and values ≥ 2.5 values were considered as presence of insulin resistance(16). Glomerular Filtration Rate (GFR) was estimated by the Cockroft-Gault equation adapted to obese patients(17). Endothelial function Endothelial function was assessed by Endothelial-dependent flow-mediated dilation (FMD) of the brachial artery(18), using an ultrasound system (Sonos5500; Hewlett-Packard-Phillips, Palo Alto, CA), equipped with vascular software for two-dimensional imaging, color and spectral Doppler ultrasound modes, internal electrocardiogram monitor and linear-array transducer with a frequency range from 7.5 to 12.0 MHz. FMD evaluation was performed in two stages: fasted at least 6 hours and 2 hours after the consumption of a small meal, according to each diet. These meals were consisted of 374.04 calories, 36g proteins, 16g carbohydrates and 18g lipids in the DD and in TD, it was composed by 361.20 calories, 24g of protein, 41g of carbohydrates and 11g of lipids. Statistical Analysis The variables were expressed as mean and standard deviation. The distribution of the date normality was analyzed by the Kolmogorov-Smirmov (KS) test. When they did not present normal distribution, a logarithm [log(Y)] transformation was performed prior to analysis. The comparison between the variables of two groups was performed using Student's t-test for independent numerical variables and Fisher's exact test for categorical variables. Comparisons between more than two groups were performed by analysis of variance (ANOVA) for repeated measures, followed by the Tukey test, if differences were found. For the sample power calculation, the Statistical Software, Statistica Ultimate Academic, version 12.7, Concurrent Network was used. Values of p ≤ 0.05 were considered for statistical significance and analysis was performed using the software [GraphPadPrism 4.0 (GraphPad Software, San Diego, CA, USA)]. Results Participants’ characteristics At the beginning of the study, the groups were matched for age, gender, weight and BMI. At 3 months, all participants of DD group (100%) were in phase 2; at 6 months, 13 participants (76.4%) were in phase 3 and 4 (23.5%) in phase 2; and at 12 months, all (100%) were already in phase 4. The TD group followed the same recommendation during the 12 months. The qualitative evaluation of the presence of ketone bodies in the urine of the DD group participants, which were still in phase 2, was positive in 94% at 3rd month and 80% at the 6th month. The following adverse effects have been reported during the course of the study: weakness, fatigue, dizziness, lack of concentration, irritability, constipation, ketone breath and social life impairment. These symptoms were of low intensity and transient, especially in the early stages of the DD diet. These adverse effects were not causes for withdrawal from the study. Anthropometry The changes in body weight, BMI, waist abdominal circumference and BMR were more effective in DD than TD group during all follow-up evaluations. The changes after 12 months in relation to baseline of the anthropometric parameters in the DD and DT groups respectively were: Weight loss (-10.6 Kg, p<0.0001 and – 2.9 Kg, p<0.0001), BMI (-3.7 Kg/m2, p<0.0001 and -1.1 Kg/m2, p<0.0001), waist abdominal circumference (-11.2 cm, p<0.0001 and -2.1 cm, p=0.0008) and BMR (-152 cal, p<0.0001 and -28 cal, p=0.0198). After 12 months, the participants of DD group reached the overweight level but the TD group was still within the obesity range. Reductions were observed in both groups, in fat mass (-5.7 Kg, p<0.0001 and -2.0 Kg, p<0.0001), and in lean mass (-4.8 Kg, p<0.0001 and -0.8 Kg, p=0.0196, in DD and DT group, respectively). Laboratory parameters and endothelial function In TD group, there was only hematocrit reduction after 6 months (p=0.0103) and glucose level after 3 months (p=0.0021) compared to baseline. In DD group, laboratory alterations occurred in relation to hemoglobin, hematocrit, triglycerides, insulin, HOMA-IR and GFR. It was observed an improvement in the triglycerides levels (172.40 ± 62.36 mg/dL and 111.90 ± 43.22 mg/dL, p=0.0001) and insulin resistance determined by HOMA-IR at all times of study (4.98 ± 3.03 and 3.26 ± 2.03, p=0.0008) at baseline and 12 months, respectively. GFR was reduced only after 3 months (132.50 ± 31.13 and 113.80 ± 24.25 mL/min, p=0.0063) in the DD group. No differences were observed in endothelial function in the two study groups, in both fasting and postprandial. Discussion This study demonstrated higher weight loss in the Dukan diet group, compared to the traditional low calorie diet. The effect of weight loss in the DD group was persistent and remained until 6th month, but in 12 months it was observed a gain around 3.41 ± 0.21 Kg. The DD is performed in phases, with severe restriction until the 3rd phase and at about the 6th month; carbohydrates and a gala meal are reintroduced, promoting a weight gain. Sacks et al. observed that regardless of the nutritional composition of the diet, obese participants that had a weight loss, after 12 months of treatment, they can gain weight, but with a reduction of approximately 11.4% of the initial weight(19). We observed that participants of TD group also presented significant weight reduction, suggesting the effectiveness of the close follow up with nutritionist and physician. Abdominal circumference is an indirect parameter of fat mass corresponding to visceral fat that is associated with a higher risk for cardiovascular diseases. In our data, we observed a reduction in waist circumference in both groups after 12 months. Moreno et al. comparing ketogenic diet with standard diet in a group of obese patients found an important reduction in abdominal circumference with partial recovery after 24 months(20). Although DEXA Scan is considered the gold standard for body composition determination, BIA is a non-invasive and relatively inexpensive method and widely used(21). A significant reduction in the relative values of body fat was observed at 3 and 6 months in the DD group and only after 3 months in the TD. Increase in percent of lean mass was observed in the DD group at 3 and 6 months, but this increase does not represent a gain of lean mass, since the relative increase is a result of the reduction of body weight, promoting a relative increase in the values of lean mass. The loss of lean mass in the DD group may be due to the low caloric intake of the diet, as Chaston et al. (2007) pointed out that diet with low-calorie diet promote marked weight loss, but there is a decline in lean mass resulting from this process(22) . In our study, in spite of consuming a large amount of protein, this nutrient alone is not enough to promote the maintenance of lean mass and exercise stimulation is still necessary, which did not happen in this study, since the participants were all sedentary. In obese individuals, weight gain after marked loss is common, with reduction in basal metabolic rate(23). Several studies have observed this phenomenon during rapid weight loss(24) and diets with low carbohydrate intake are among the factors that influence metabolic adaptation. Some studies suggest that low amounts of carbohydrate (<45%) decrease the basal metabolic rate during and after weight loss. This type of diet can promote fat mass loss and preservation of lean mass during weight loss, reducing the basal metabolic rate. Reduction in BMR was observed in both groups, but in the DD group, the reduction occurred at all times in relation to baseline whereas in TD group the reduction was greater only after 6 months of intervention. Improvement in insulin resistance and triglycerides were observed only in the DD group. Individuals with insulin resistance have greater difficulty to metabolize carbohydrates, diverting a greater amount of dietary carbohydrates to the liver, where much of it is converted to fat (lipogenesis), rather than being oxidized in energy in the skeletal muscle. For this reason, very low carbohydrate diets applied in obese individuals, in addition to leading to weight loss also improves glycemic and lipid control. The effects of the very prolonged ketogenic diet are still poorly investigated and for this reason this diet should only be used for a limited period (from 3 weeks to a few months) to stimulate fat loss, improve metabolism, and then adjusting a transition to a normal diet(25). No changes in levels of total cholesterol, HDL-c and LDL-c were observed in any group. However, only in the DD group there was a significant reduction in TG level. In general, diets with reduced carbohydrates and high levels of proteins and fats increase LDL-c and TG levels showing beneficial effects of the ketogenic diet on cardiovascular risk factors. Most studies show that reducing carbohydrates can bring significant benefits in reducing total cholesterol, increases in HDL-c and reduction of triglycerides in the blood. HMG-CoA reductase, a key enzyme in the synthesis of endogenous cholesterol is activated by insulin, so that a reduction in blood glucose and hence insulin levels, leads to lower cholesterol synthesis. Thus, a reduction in dietary carbohydrate associated with adequate cholesterol consumption leads to inhibition of cholesterol biosynthesis(26). When insulin is elevated, lipolysis is reduced and lipogenesis is increased, resulting in overproduction of VLDL containing TG, formation of small and dense LDL particles and reduction of HDL. Low concentrations of glucose and insulin also reduce the expression of the carbohydrate-sensitive response element binding protein (ChREBP) transcription factor, and expression of the binding protein of the sterol regulatory element (SREBP-1c), responsible for the synthesis of fatty acids, as well as their incorporation into triglycerides and phospholipids, activating the main lipogenic enzymes, reducing hepatic lipogenesis and VLDL production(27). When we evaluated the GFR, a reduction only in DD group was observed at 3 months of intervention, but still in normal reference levels. Our results did not show significant changes in serum creatinine levels, but GFR decrease in DD group. Carbohydrate-restricted diets have higher amounts of protein may affect glomerular filtration leading to progressive loss of renal function(28). In the study conducted by Brinkworfh et al. (2010), renal function was evaluated in 68 obese individuals without renal dysfunction who consumed two similar hypocaloric diets for one year, one with carbohydrate reduction and another with high carbohydrate content, and observed that creatinine serum levels and the GFR did not change in any of the dietary groups(29). In general, endothelial function improves after weight loss in obese individuals(30). However, associations between changes in endothelial function with anthropometric and biochemical parameters are still controversial(31). We observed that the endothelial function did not present a significant difference in the two study groups, both in fasting and in the 2 hours postprandial. Volek et al. (2009) observed that low-carbohydrate diet improves postprandial vascular function compared to a low-fat diet in overweight individuals with moderate hypertriglyceridemia(32). Low-carbohydrate diets, may improve vascular function in individuals with metabolic adaptations(32) and carbohydrate-restricted diets may induce benefits in endothelial function in the presence of insulin resistance, since impaired insulin action may be related to endothelial dysfunction. In our study, the meal offered for postprandial evaluation was not high in fat, but correspond to the diet proposed in each group. According to Nicholls et al. (2006), a single carbohydrate-restricted meal does not alter endothelial function(33) and this may be the reason we did not observe a change in endothelial function in the DD group in this study. Conclusion Comparing the nutritional and laboratory effects of traditional and hyper-protein diets with carbohydrate reduction, we can conclude that Dukan diet was more effective than traditional diet for weight loss, as well as for laboratory parameters and without changes in endothelial function, in the 12-months follow-up of obese subjects. Conflict of interest No conflict of interest. Acknowledgement Patricia Naomi Sakae had a scholarship from CAPES – Brazil. References Gogebakan O.; Kohl A.; Osterhoff MA.; van Baak MA.; Jebb SA.; Papadaki A.; et al. Effects of weight loss and long-term weight maintenance with diets varying in protein and glycemic index on cardiovascular risk factors: the diet, obesity, and genes (DiOGenes) study: a randomized, controlled trial. Circulation. 2011, 124(25), 2829-2838. Merino J.; Kones R.; Ferre R.; Plana N.; Girona J.; Aragones G.; et al. 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... Furthermore, it was tested by the University of Granada, in laboratory rats (according to the first phase of the four that consists of the Dukan diet), which developed severe kidney problems including formation of kidney stones, a decrease of up to 88% in urinary citrate and a pH markedly more acid urinary 48 . In 2014, a case report 49 reflected that a woman 42-year-old Iranian after two days of starting the Dukan diet is admitted with nausea, vomiting and a secondary ketoacidosis and Wyka et al. 50 observed 51 women who followed this diet reducing 15 kg in weight during the treatment for 8 to 10 weeks (means losing up to 1.87 kg/week), but it could be a health risk causing osteoporosis and kidney disease, liver and cardiovascular diseases. ...
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Introduction: In the last years, confusing or misleading use of the term called miracle or magic diets, using to weight loss treatment, has increased, along with several classification of them. Objectives: The purpose of this narrative review is to discuss miracle slimming diets and proposal new term and new classification for these diets. Methods: A narrative review up to September 2021 was carried out in the PubMed, Google Scholar, and Web of Knowledge. Furthermore, this strategy was complemented with a comprehensive search of the ‘grey’ literature [7] based in four different searching strategies: i) grey literature databases, ii) customized Google search engines, iii) targeted websites, and iv) consultation with contact experts. Results: Our proposal is to use the new concept called hazardous slimming diets defined as diets that propose rapid weight loss (> 1 kg/week), to be performed effortlessly, without the super-vision of a medical/nutritional professional, excessive energy restrictions and/or exclusion from the diet of food or nutrients for the body. Furthermore, the development of a new algorithm reflected as is possible to classify the diet as non-effective, hazardous and effective diet. Conclusions: Our review could help to classify and develop a new terminology about the miracle slimming diets focusing in the knowledge to guarantee the quality in the treatments for weight loss.
... Individuals following a low-carbohydrates diet (carbohydrates provided less than 45% total energy intake) consumed lower amounts of vitamin C, vegetables and fruits than the subjects in the control group [105]. Additionally, a diet based on guidelines of the Dukan diet (high protein diet, carbohydrates provide 10-25% of total energy intake) results in a lower vitamin C intake (2.5-4.5 mg) [106]. In fact, the ascorbic acid intake was 94 ± 59 mg in the Atkins diet. ...
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... Such diet does not allow to supply the demand of brain cells on glucose. Body mass reduction on Dukan diet is connected to total calories limitation, increased satiety due to the development of ketosis formed as an effect of glucose deficiency, but also to dehydration, which occurs due to the release of glycogen from muscles and liver (the loss of 400g of glycogen is related to the loss of 1kg of water) [23,24]. Additionally, each of the phases of this diet increases the risk of cardiovascular diseases as a result of high consumption of saturated fatty acids and cholesterol, with simultaneous low consumption of folates, which regulate the concentration of homocysteine in blood [22]. ...
... A dieta Dukan, por sua vez, apresentou VRB inicialmente crescente entre as 78ª e 99ª semanas embora, a partir daí verifica-se queda da linha de tendência com curtos picos esporádicos (Figura 7). Mesmo apresentando característica mais processual que outras dietas da moda, a dieta Dukan também prescreve baixa quantidade de carboidratos e alto valor protéico 57,58 . Teve origem a partir do método Dukan, que foi proposto pelo médico nutrólogo Pierre Dukan a partir de estudos realizados nos últimos 40 anos 59 e é baseada em quatro fases. ...
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Lately, we've witnessed the emergence of obesity as a prominent concern for public health and the economy. This issue commands serious attention, impacting millions worldwide, particularly in the most developed nations. Practical approaches to tackling obesity involve tailored physical activity and dietary interventions overseen by qualified healthcare professionals. Nonetheless, some individuals opt for quicker routes, embracing dietary regimens that promise rapid and effortless weight reduction yet lack substantiated scientific backing. Given the potential hazards these approaches pose to well-being, this calls for immediate address, occasionally leading to unexpected and severe consequences. In this review, we aim to analyze the curiosities of popular diets embraced by adults from the 1960s to the present day, including the scientific justification that supports or contradicts their effectiveness.
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BackgroundA higher protein to carbohydrate ratio in the diet may potentiate weight loss, improve body composition and cardiometabolic risk, including glucose homeostasis in adults. The aim of this randomised control trial was to determine the efficacy of two structured lifestyle interventions, differing in dietary macronutrient content, on insulin sensitivity and body composition in adolescents. We hypothesised that a moderate-carbohydrate (40-45% of energy), increased-protein (25-30%) diet would be more effective than a high-carbohydrate diet (55-60%), moderate-protein (15%) diet in improving outcomes in obese, insulin resistant adolescents.Methods Obese 10¿17 year olds with either pre-diabetes and/or clinical features of insulin resistance were recruited at two hospitals in Sydney, Australia. At baseline adolescents were prescribed metformin and randomised to one of two energy restricted diets. The intervention included regular contact with the dietician and a supervised physical activity program. Outcomes included insulin sensitivity index measured by an oral glucose tolerance test and body composition measured by dual-energy x-ray absorptiometry at 12 months.ResultsOf the 111 adolescents recruited, 85 (77%) completed the intervention. BMI expressed as a percentage of the 95th percentile decreased by 6.8% [95%CI: ¿8.8 to ¿4.9], ISI increased by 0.2 [95%CI: 0.06 to 0.39] and percent body fat decreased by 2.4% [95%CI: ¿3.4 to ¿1.3]. There were no significant differences in outcomes between diet groups at any time.Conclusion When treated with metformin and an exercise program, a structured, reduced energy diet, which is either high-carbohydrate or moderate-carbohydrate with increased-protein, can achieve clinically significant improvements in obese adolescents at risk of type 2 diabetes.Trial registrationAustralian New Zealand Clinical Trail Registry ACTRN12608000416392. Registered 25 August 2008.
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