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onlineijedo.positivepress.net
IJEDO
Italian Journal of Eating Disorders and Obesity
ORIGINAL ARTICLE
IJEDO 2020;2:5-7
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Riccardo Dalle Grave, MD ( ) rdalleg@gmail.com
Received: 11 January 2020; Accepted: 20 January 2020; Published online: 17 February 2020. doi:10.32044/ijedo.2020.02
Abstract
Intermitting fasting has been proposed as a dietary strategy to improve general
health indicators, slow or reverse disease processes and aging. However, data
supporting the beneficial health effects of intermittent fasting mainly derive from
preclinical studies in animals and short-term clinical studies on weight loss
and non-communicable disease risk factors, with no significant differences on
these outcomes when intermittent fasting has been compared with moderate
continuous energy restriction in humans. No data are available on the effect of
intermitting fasting on clinically important outcomes in humans, such as the onset
of cardiovascular diseases, cancer, and life expectancy. Instead, several studies
found an association between delayed eating (i.e., spending many hours during the
day without eating) and increased risk of developing episodes of overeating and
binge eating. Moreover, the procedure of regular eating, adopted by the “enhanced”
cognitive behavior therapy for eating disorders (CBT-E), results in a rapid decease
in the frequency of binge-episodes in patients with bulimia nervosa and binge-
eating disorders. These data indicate that regular eating, not intermitting fast, is the
best choice for adopting a healthy eating control and avoiding the development of
unregulated and, in some cases, disturbed eating behavior.
Key words
Intermittent fasting
Regular eating
Starvation
Life expectancy
Health disease
Aging
Eating disorders
Bulimia nervosa
Binge-eating disorder
Regular eating, not intermittent fasting,
is the best strategy for a healthy eating control
Riccardo Dalle Grave
Depar tment of Eating and Weight Disorders, Villa Garda Hospital, Garda ( VR), Italy
Intermittent fasting has been recently proposed as an eating
pattern strategy to elicit, through the metabolic switch from
the use of glucose as fuel source to the use of fatty acids and
ketone bodies, the improvement of insulin resistance, obe-
sity, dyslipidemia, high blood pressure and cognitive fun-
ctions, the increased resistance to stress, the suppression of
inflammation and the increase of life expectancy (de Cabo
& Mattson, 2019). These dietary practices in its more com-
mon forms (e.g., alternate fasting days; 5:2 intermittent
fasting, i.e., fasting 2 days each week; daily time-restricted
feeding) (Anton et al., 2018) has been proposed to treat
obesity, diabetes, cardiovascular diseases, cancer, neurode-
generative diseases, asthma, multiple sclerosis, osteoarthri-
tis, surgical tissue lesions and ischemic and to prolong life
expectancy (de Cabo & Mattson, 2019).
Data supporting the beneficial effects of intermittent
fasting derives from preclinical studies on animals (e.g.
rats) (Anton et al., 2018; Swindell, 2012). The few clini-
cal published studies assessed only the short-term (weeks
or months) effect of this intervention on weight loss and
some non-communicable diseases risk factors. To date no
data are available on the effect of intermitting fasting on
clinically important outcomes, such as the onset of cardio-
vascular diseases, cancer, and lifer expectancy in humans.
Furthermore, most studies did not compare the long-term
effects of intermittent fasting with continuous energy re-
Riccardo Dalle Grave
doi:10.32044/ijedo.2020.02
IJEDO
Italian Journal of Eating Disorders and Obesity
6
onlineijedo.positivepress.net IJEDO 2020;2:5-7
striction. Therefore, it is not known whether the observed
positive effects on risk factors are the result of intermittent
fasting or calorie restriction per se.
The only published clinical study with long-term outco-
me data (i.e., 24 months) on weight loss and cardiovascular
risk factors is a one-year randomized parallel trial which
randomized 332 adults with overweight or obesity to one of
three groups: (1) continuous energy restriction (1000 kcal/
day for women and 1200 kcal/day for men); (2) week-on-
week-off energy restriction (alternating between the same
energy restriction as the continuous group for one week and
one week of habitual diet); or (3) 5:2 (500 kcal/day on mo-
dified fast days each week for women and 600 kcal/day for
men, the 2 days of energy restriction could be consecutive
or non-consecutive). The study did not find significant dif-
ferences in weight loss and in the modification of the cardio-
vascular risk factors among the three groups at both 12 and
24 months (Headland, Clifton, & Keogh, 2019, 2020).
Other tr ials with shor ter duration achieved t he same con-
clusion as the Headland et al. study (2020). For example, a
short-term randomized study, comparing alternate-day fa-
sting with moderate daily caloric restriction in adults with
obesity, found no significant between-group differences in
change in weight body composition, lipids and insulin sen-
sitivity index after 8-weeks of treatment, and no significant
differences in weight regain after 24 weeks of unsupervised
follow-up (Catenacci et al., 2016). The same conclusion was
reached by a 12-month trial that found no significant diffe-
rences in adherence, weight loss and maintenance, and car-
diovascular protection between intermittent fasting (25%
of energy needs on fast days; 125% of energy needs on al-
ternating “feast days”) compared to a moderate continuous
energy restriction (75% of energy needs every day) (Tre-
panowski et al., 2017). The results of these studies confirm
the conclusions of a systematic metanalytical review of 9
studies of a minimum duration of 6 months, in which no
difference in weight loss was observed between continuous
calorie restriction and intermittent fasting (Headland, Cli-
fton, Carter, & Keogh, 2016).
Although there are no significant differences in terms
of weight loss and improvement of cardiovascular risk fac-
tors between intermittent fasting and continuous energy
restriction, several studies found an association between
delayed eating (i.e., spending many hours during the day
without eating) and increased risk of developing episodes
of overeating and binge eating. A laboratory experiment
found that participants deprived of food for 6-hour con-
sumed significantly more calories at the buffet compared
to subjects in the 1-hour food deprivation condition (Tel-
ch & Agras, 1996). Studies on binge-eating disorder (BED)
have observed that patients with overweight and BED who
ate three meals per day weighed significantly less, and had
significantly fewer binge eating episodes, than those who
did not regularly eat three meals per day (Masheb & Grilo,
2006). Moreover, regular consumption of breakfast, lunch
and dinner was significantly correlated with a lower body
mass index in people with obesity and BED (Masheb, Grilo,
& White, 2011). Research has also shown that dieting signi-
ficantly predicted future weight gain in normal weight in-
dividuals (Lowe, Doshi, Katterman, & Feig, 2013), and was
a risk factor for the development of eating disorders of cli-
nical severity (Schaumberg & Anderson, 2016; St ice, 2016).
The most important evidence in favor of regular eating
pattern (3 + 2 + 0), however, derives from the results of stu-
dies that assessed the efficacy and effectiveness of “enhan-
ced” cognitive behavioral therapy (CBT-E) for eating disor-
ders (Dalle Grave & Calugi, 2020; Fairburn, 2008). CBT-E
is based on a theory postulating that delayed eating and the
adoption of extreme and rigid dietary rules are the most
potent mechanisms maintaining binge-eating episodes
(Fairburn, Cooper, & Shafran, 2003). For this reason, a key
procedure adopted by CBT-E is “regular eating” that sug-
gest patients to plan in advance 3 main meals (breakfast,
lunch and dinner) and 2 snacks (mid-morning snack and
mid-afternoon snack) and not eating between these inter-
vals: a procedure also called 3 + 2 + 0. Randomized and
cohort studies have shown that regular eating procedures
result in a rapid decrease in the frequency of binge-episo-
des in patients with bulimia nervosa (Dalle Grave, Calugi,
Sartirana, & Fairburn, 2015; Fairburn et al., 2009) and BED
(Grilo & Masheb, 2005). A study assessing the efficacy of
CBT for bulimia nervosa has also found that participants
who ate 80 meals and at least 21 afternoon snacks in the
previous month reported the highest abstinence rate (70%)
from binge-eating episodes (Shah, Passi, Bryson, & Agras,
2005). This finding was also observed in a study using CBT
guided self-help in patients with binge-eating episodes
(Zendegui, West, & Zandberg, 2014). These results led to
affirm that regular eating is probably the single most im-
portant procedure in the treatment of eating disorders with
binge-eating episodes (Fairbu r n, 2013).
In conclusion, there are no evidences, supported by
long-term randomized controlled trials, that intermittent
fasting produces additional clinical benefits, compared to
healthy and regular eating patterns, and greater weight
loss, compared to a moderate continuous energy restri-
ction. Instead, there are some evidences that delayed ea-
ting increases the risk of developing episodes of overeating
Riccardo Dalle Grave
doi:10.32044/ijedo.2020.02
IJEDO
Italian Journal of Eating Disorders and Obesity
7
onlineijedo.positivepress.net IJEDO 2020;2:5-7
and binge eating. For these reasons, it is inappropriate to
recommend intermitting fasting as a healthy eating practi-
ce. Regular eating, preferably based on the Mediterranean
diet model (Estruch et al., 2018), is the best choice to re-
duce the risk of disease and to avoid the development of
unregulated and, in some cases, disturbed eating behavior.
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