[Show abstract][Hide abstract] ABSTRACT: Nonalcoholic fatty liver disease (NAFLD) and its association with insulin resistance are increasingly recognized as major health burdens. The main objectives of this study were to assess the relation between liver lipid content and serum lipids, markers of liver function and inflammation in healthy overweight subjects, and to determine whether caloric restriction (CR) (which improves insulin resistance) reduces liver lipids in association with these same measures.
Forty-six white and black overweight men and women (BMI = 24.7-31.3 kg/m(2)) were randomized to "control (CO)" = 100% energy requirements; "CR" = 25%; "caloric restriction and increased structured exercise (CR+EX)"= 12.5% CR + 12.5% increase in energy expenditure through exercise; or "low-calorie diet (LCD)" = 15% weight loss by liquid diet followed by weight-maintenance, for 6 months. Liver lipid content was assessed by magnetic resonance spectroscopy (MRS) and computed tomography (CT). Lipid concentrations, markers of liver function (alanine aminotransferase (ALT), alkaline phosphatase (ALK)), and whole-body inflammation (tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), high-sensitivity C-reactive protein (hsCRP)) were measured in fasting blood.
At baseline, increased liver lipid content (by MRS) correlated (P < 0.05) with elevated fasting triglyceride (r = 0.52), ALT (r = 0.42), and hsCRP (r = 0.33) concentrations after adjusting for sex, race, and alcohol consumption. With CR, liver lipid content was significantly lowered by CR, CR+EX, and LCD (detected by MRS only). The reduction in liver lipid content, however, was not significantly correlated with the reduction in triglycerides (r = 0.26; P = 0.11) or with the changes in ALT, high-density lipoprotein (HDL)-cholesterol, or markers of whole-body inflammation.
CR may be beneficial for reducing liver lipid and lowering triglycerides in overweight subjects without known NAFLD.
[Show abstract][Hide abstract] ABSTRACT: This study tested the reliability and validity of measuring children's food intake with the digital photography method and the effects of second servings upon food intake. Food intake was measured in a school cafeteria for 5 days. Adiposity was assessed with body impedance analysis and body mass index, expressed as percentile rank. Mood and self-esteem were assessed with questionnaires. Estimates of food intake were highly reliable between two registered dietitians who independently estimated food intake. Boys ate more food than girls. A significant association between food intake and adiposity supported convergent validity. Non-significant correlations between food intake and depressed mood and self-esteem supported discriminant validity. When second servings were available, more food was selected and discarded, but mean food intake did not increase. Children who returned for second servings, however, ate more food when second servings were available, and a trend suggested that they also ate more food when second servings were not available. These findings support the reliability and validity of measuring children's food intake using digital photography and demonstrate its utility for studies of food intake and body weight.
No preview · Article · May 2007 · Eating Behaviors
[Show abstract][Hide abstract] ABSTRACT: There is debate over the independent and combined effects of dieting and increased physical activity on improving metabolic risk factors (body composition and fat distribution).
The objective of the study was to conduct a randomized, controlled trial (CALERIE) to test the effect of a 25% energy deficit by diet alone or diet plus exercise for 6 months on body composition and fat distribution.
This was a randomized, controlled trial.
The study was conducted at an institutional research center.
Thirty-five of 36 overweight but otherwise healthy participants (16 males, 19 females) completed the study.
Participants were randomized to either control (healthy weight maintenance diet, n = 11), caloric restriction (CR; 25% reduction in energy intake, n = 12), or caloric restriction plus exercise (CR+EX; 12.5% reduction in energy intake + 12.5% increase in exercise energy expenditure, n = 12) for 6 months.
Changes in body composition by dual-energy x-ray absorptiometry and changes in abdominal fat distribution by multislice computed tomography were measured. Results: The calculated energy deficit across the intervention was not different between CR and CR+EX. Participants lost approximately 10% of body weight (CR: - 8.3 +/- 0.8, CR+EX: - 8.1 +/- 0.8 kg, P = 1.00), approximately 24% of fat mass (CR: - 5.8 +/- 0.6, CR+EX: - 6.4 +/- 0.6 kg, P = 0.99), and 27% of abdominal visceral fat (CR: 0.9 +/- 0.2, CR+EX: 0.8 +/- 0.2 kg, P = 1.00). Both whole-body and abdominal fat distribution were not altered by the intervention.
Exercise plays an equivalent role to CR in terms of energy balance; however, it can also improve aerobic fitness, which has other important cardiovascular and metabolic implications.
[Show abstract][Hide abstract] ABSTRACT: A randomized controlled trial tested the efficacy of an internet-based lifestyle behavior modification program for African-American girls over a 2-year period of intervention.
Fifty-seven overweight (mean BMI percentile, 98.3) African-American girls (mean age, 13.2 years) were randomly assigned to an interactive behavioral internet program or an internet health education program, the control condition. Overweight parents were also participants in the study. Forty adolescent-parent dyads (70%) completed the 2-year trial. Outcome data including BMI, body weight, body composition, and weight loss behaviors were collected at baseline and at 6-month intervals. A computer server tracked use of the web sites.
An intention-to-treat statistical approach was used, with the last observation carried forward. In comparison with the control condition, adolescents in the behavioral program lost more mean body fat (BF) (-1.12 +/- 0.47% vs. 0.43 +/- 0.47% BF, p < 0.05), and parents in the behavioral program lost significantly more mean body weight (-2.43 +/- 0.66 vs. -0.35 +/- 0.64 kg, p < 0.05) during the first 6 months. This weight loss was regained over the next 18 months. After 2 years, differences in fat for adolescents (-0.08 +/- 0.71% vs. 0.84 +/- 0.72% BF) and weight for parents (-1.1 +/- 0.91 vs. -0.60 +/- 0.89 kg) did not differ between the behavioral and control programs.
An internet-based weight management program for African-American adolescent girls and their parents resulted in weight loss during the first 6 months but did not yield long-term loss due to reduced use of the web site over time.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this article was to determine the relationships among total body fat, visceral adipose tissue (VAT), fat cell size (FCS), ectopic fat deposition in liver (intrahepatic lipid [IHL]) and muscle (intramyocellular lipid [IMCL]), and insulin sensitivity index (S(i)) in healthy overweight, glucose-tolerant subjects and the effects of calorie restriction by diet alone or in conjunction with exercise on these variables.
Forty-eight overweight volunteers were randomly assigned to four groups: control (100% of energy requirements), 25% calorie restriction (CR), 12.5% calorie restriction +12.5% energy expenditure through structured exercise (CREX), or 15% weight loss by a low-calorie diet followed by weight maintenance for 6 months (LCD). Weight, percent body fat, VAT, IMCL, IHL, FCS, and S(i) were assessed at baseline and month 6.
At baseline, FCS was related to VAT and IHL (P < 0.05) but not to IMCL. FCS was also the strongest determinant of S(i) (P < 0.01). Weight loss at month 6 was 1 +/- 1% (control, mean +/- SE), 10 +/- 1% (CR), 10 +/- 1% (CREX), and 14 +/- 1% (LCD). VAT, FCS, percent body fat, and IHL were reduced in the three intervention groups (P < 0.01), but IMCL was unchanged. S(i) was increased at month 6 (P = 0.05) in the CREX (37 +/- 18%) and LCD (70 +/- 34%) groups (P < 0.05) and tended to increase in the CR group (40 +/- 20%, P = 0.08). Together the improvements in S(i) were related to loss in weight, fat mass, and VAT, but not IHL, IMCL, or FCS.
Large adipocytes lead to lipid deposition in visceral and hepatic tissues, promoting insulin resistance. Calorie restriction by diet alone or with exercise reverses this trend.
[Show abstract][Hide abstract] ABSTRACT: To compare the accuracy of percentage body fat (%BF) estimates between bioelectrical impedance analysis (BIA) and DXA in obese African-American women.
Fifty-five obese African-American women (mean age, 45 years; mean BMI, 38; mean %BF, 48%) were studied. BF was assessed by both BIA (RJL Systems BIA 101Q; RJL Systems, Clinton Township, MI) and DXA (Hologic QDR-2000 Bone Densitometer; Hologic Inc., Bedford, MA). Generalized and ethnicity- and obese-specific equations were used to calculate %BF from the BIA. Bland-Altman analyses were used to compare the agreement between the BIA and the DXA, with the DXA serving as the criterion measure.
Two of the generalized equations provided consistent estimates across the weight range in comparison with the DXA estimates, whereas most of the other equations increasingly underestimated %BF as BF increased. One of the generalized and one of the ethnicity-specific equations had mean differences that were not significantly different from the DXA value.
The findings show that the Lukaski equation provided the most precise and accurate estimates of %BF in comparison with the QDR 2000 and provide preliminary support for the use of this equation for obese African-American women.
[Show abstract][Hide abstract] ABSTRACT: This study evaluated changes in depression, anxiety, and stress during Army basic training. During week 1 of training, 139 soldiers from two companies volunteered for participation. In week 8, 93 soldiers were available for retesting. Self-reports of depressive symptoms and perceptions of stressfulness at both assessments fell within the normative range for nonclinical samples, whereas endorsement of anxiety symptoms remained slightly elevated, in the mild range. Women endorsed higher levels of anxiety (F = 8.87, p < 0.01) than did men. No gender or ethnicity differences were noted for changes in psychological distress over time. Regression analyses showed that subjects with the highest levels of initial distress on the anxiety, depression, and stress measures had the most change at the end of 8 weeks of training (r values between 0.61 and 0.39; all p < 0.01). Results suggest that initial levels of psychological distress are slightly elevated for anxiety but most individuals adapt to the stress of basic training, with normal levels of distress by the last week.
No preview · Article · Mar 2006 · Military medicine
[Show abstract][Hide abstract] ABSTRACT: This cross-sectional research study tested the hypothesis that body image estimates of African-American females differ as a function of age. To test this hypothesis, body image estimates of 379 African-American females, ranging in age from 16 to 96 years, were contrasted as a function of age group, while statistically controlling body mass index. Three body size estimates, current body size, ideal body size, and reasonable body size were measured using the Body Image Assessment for Obesity. The discrepancies between current and ideal body size estimates and between current and reasonable body size estimates were also analyzed to assess for differences in body size dissatisfaction. The study found that younger African-American women (16 to 35 years) differed from older African-American women (>35 years) on measures of body size dissatisfaction. Women in the age range of 26 to 35 years reported higher estimates of current body size in comparison to women older than 35 years. The youngest age group (16 to 25 years) reported thinner ideal body size goals in comparison to women who were slightly older (26 to 35 years) and women who were older than 75 years. The pattern of body image estimates across a large age range suggests that younger African-American women, in comparison to older African-American women, may have body images that may make them more susceptible to eating disorders.
No preview · Article · Dec 2005 · Eating and weight disorders: EWD
[Show abstract][Hide abstract] ABSTRACT: This randomized controlled trial tested the efficacy of an internet-based lifestyle behavior modification program for weight management in African-American girls.
African-American girls were randomly assigned to an interactive behavioral internet program or an internet health education program, the control condition. The behavioral intervention included internet counseling and was highly interactive. The control intervention was a passive (non-interactive) educational program. Parents were also participants in the study. Participants in both treatment groups met in face-to-face sessions on four occasions over the first 12 weeks of a 6-month intervention.
The study enrolled 57 African-American adolescent girls (ages 11 to 15 years) who were overweight or obese and had at least one biological parent who was obese [body mass index (BMI) >30 kg/m2]. Of the 57 participants, 50 (88%) completed the 6-month trial.
Outcome data, including BMI, body weight, body composition, dietary intake, and weight loss behaviors were collected at baseline and 6-months later. A computer server tracked utilization of the websites. Participation in the program was measured by number of "hits" on the website.
Compared to the control condition, adolescents in the behavioral treatment lost more body fat (group difference =1.6% body fat) and parents lost significantly more body weight (group difference =2.1 kg). Utilization of the behavioral website by adolescents and parents was associated with positive outcome. Dietary fat intake was lowered for adolescents and parents in the behavioral treatment group.
An internet-based behavioral intervention was superior to internet-based health education and yielded decreased body fat for adolescent girls and decreased body weight for parents.
No preview · Article · Oct 2005 · Eating and weight disorders: EWD
[Show abstract][Hide abstract] ABSTRACT: To compare the estimation of body fat between bioelectrical impedance analysis (BIA) and dual energy X-ray absorptiometry (DEXA) in overweight, African-American female adolescents.
In total, 54 African-American adolescent female subjects were recruited for Study 1. Each adolescent's body mass index was greater than the 85th percentile and their average body fat was 45% according to DEXA. A total of 26 African-American adolescent female subjects were available for Study 2, and had an average body fat of 26% according to DEXA.
Percent body fat was measured by DEXA and BIA. Seven different BIA equations were tested. Both sets of data were analyzed using Bland-Altman regression analyses, utilizing percent body fat measured by DEXA as the criterion.
The Kushner equation provided estimates that were unaffected by body fat in both studies. Estimates were unbiased when applied to the exclusively overweight sample and biased when utilized with the separate sample of normal weight and obese girls. The remaining equations were biased, provided inconsistent estimates across body weight, or were biased and provided inconsistent estimates. Ethnicity-specific and ethnicity-combined equations performed similarly in the obese sample, but became more disparate when applied to a sample encompassing a wider body weight range. The limits of agreement between all BIA equations and the DEXA estimates ranged from 6 to 9%.
The study suggests that the Kushner BIA equation is appropriate for use with African-American female adolescents across the weight spectrum, while the majority of BIA equations underestimated percent body fat as body fat increased.
Full-text · Article · Jul 2005 · International Journal of Obesity
[Show abstract][Hide abstract] ABSTRACT: The primary objective of this study was to test the comparability of digital photography and visual estimation procedures for estimating food intake.
The study sample included 71 breakfast meals and 59 lunch meals eaten in a university cafeteria during a single day. A total of 66 different foods were employed as test foods that could be selected by the students. Food selections and plate waste, as estimated by digital photography and visual estimation, were compared. For digital photography, three observers independently estimated portion sizes of each food item based upon digital photographs. One observer estimated portion sizes in the cafeteria setting, using visual estimation, a method that has been validated in other studies.
To test the accuracy of the two procedures for measuring food intake, the estimates of food weights derived from both procedures were compared using Bland-Altman regression. In comparison to visual estimation, the digital photography method yielded comparable estimates of food selections, plate waste, and total food intake for seven of nine comparisons. The two methods of estimating food portions yielded comparable results for most (78%) types of foods. The two methods also yielded similar variability.
These findings suggest that the digital photography method is an alternative to the traditional method of estimating food intake via direct observation.
No preview · Article · Apr 2004 · Eating and weight disorders: EWD
[Show abstract][Hide abstract] ABSTRACT: The primary goal was to test the validity of digital photography for measuring food portion sizes compared with weighed foods and with direct visual estimation.
A total of 60 test meals consisting of 10 different portion sizes from six different university cafeteria menus were prepared and weighed.
Food selections and plate waste, as estimated by digital photography and direct visual estimation, were compared with weighed foods. For each method, three observers independently estimated portion sizes of each food. Observers expressed the portion sizes as a percentage of a standard serving. These percentages were multiplied by the weight of the standard portion to yield estimated weights. Statistical analyses To test validity, the estimates of food weights derived from both methods were compared with weighed foods using correlations and were compared with each other using Bland-Altman regression analysis.
For the digital photography and direct visual estimation methods, estimates of the portion sizes for food selections, plate waste, and food intake were highly correlated with weighed foods. Both methods tended to yield small overestimates or underestimates. Bland-Altman regression found the two estimation methods to yield comparable results (bias less than 1.5 g).
These findings support the validity of the digital photography method for measuring portion sizes. Digital photography may be most useful for measuring food intake in settings that allow for the direct observation of food selections and plate waste but require minimum disruption of the eating environment, and allow unhurried estimates of portion sizes.
No preview · Article · Oct 2003 · Journal of the American Dietetic Association
[Show abstract][Hide abstract] ABSTRACT: This research project evaluated changes in food selections, food intake, and body weight during 8 weeks of basic combat training (BCT). During the first week of BCT, 139 soldiers from two companies volunteered for participation in the study. In the eighth week of BCT, 92 soldiers were available for retesting. A digital photography method for measuring food selections and food intake was developed for this study. Fruit intake of soldiers was very low at the beginning and end of BCT. Food intake for grains and milk products was low during the first week of BCT but improved by the end of BCT. Average body weight decreased during the 8 weeks of BCT, but heavier soldiers tended to lose weight and thinner soldiers tended to gain weight. These findings suggest that the overall effect of BCT was a trend toward improvement of healthy eating and healthy body weight.
No preview · Article · Apr 2002 · Military medicine
[Show abstract][Hide abstract] ABSTRACT: Context
Prolonged calorie restriction increases life span in rodents. Whether prolonged calorie restriction affects biomarkers of longevity or markers of oxidative stress, or reduces metabolic rate beyond that expected from reduced metabolic mass, has not been investigated in humans.Objective
To examine the effects of 6 months of calorie restriction, with or without exercise, in overweight, nonobese (body mass index, 25 to <30) men and women.Design, Setting, and Participants
Randomized controlled trial of healthy, sedentary men and women (N = 48) conducted between March 2002 and August 2004 at a research center in Baton Rouge, La.Intervention
Participants were randomized to 1 of 4 groups for 6 months: control (weight maintenance diet); calorie restriction (25% calorie restriction of baseline energy requirements); calorie restriction with exercise (12.5% calorie restriction plus 12.5% increase in energy expenditure by structured exercise); very low-calorie diet (890 kcal/d until 15% weight reduction, followed by a weight maintenance diet).Main Outcome Measures
Body composition; dehydroepiandrosterone sulfate (DHEAS), glucose, and insulin levels; protein carbonyls; DNA damage; 24-hour energy expenditure; and core body temperature.Results
Mean (SEM) weight change at 6 months in the 4 groups was as follows: controls, −1.0% (1.1%); calorie restriction, −10.4% (0.9%); calorie restriction with exercise, −10.0% (0.8%); and very low-calorie diet, −13.9% (0.7%). At 6 months, fasting insulin levels were significantly reduced from baseline in the intervention groups (all P<.01), whereas DHEAS and glucose levels were unchanged. Core body temperature was reduced in the calorie restriction and calorie restriction with exercise groups (both P<.05). After adjustment for changes in body composition, sedentary 24-hour energy expenditure was unchanged in controls, but decreased in the calorie restriction (−135 kcal/d [42 kcal/d]), calorie restriction with exercise (−117 kcal/d [52 kcal/d]), and very low-calorie diet (−125 kcal/d [35 kcal/d]) groups (all P<.008). These “metabolic adaptations” (~ 6% more than expected based on loss of metabolic mass) were statistically different from controls (P<.05). Protein carbonyl concentrations were not changed from baseline to month 6 in any group, whereas DNA damage was also reduced from baseline in all intervention groups (P <.005).Conclusions
Our findings suggest that 2 biomarkers of longevity (fasting insulin level and body temperature) are decreased by prolonged calorie restriction in humans and support the theory that metabolic rate is reduced beyond the level expected from reduced metabolic body mass. Studies of longer duration are required to determine if calorie restriction attenuates the aging process in humans.Trial Registration
ClinicalTrials.gov Identifier: NCT00099151
Figures in this Article
Prolonged calorie restriction increases life span in rodents and other shorter-lived species.1 Whether this occurs in longer-lived species is unknown, although the effect of prolonged calorie restriction in nonhuman primates is under investigation. One hypothesis to explain the antiaging effects of calorie restriction is reduced energy expenditure with a consequent reduction in the production of reactive oxygen species (ROS).2- 3 However, other metabolic effects associated with calorie restriction, including alterations in insulin sensitivity and signaling, neuroendocrine function, stress response, or a combination of these, may retard aging.4
Total energy expenditure is made up of resting energy expenditure (50%-80% of energy), the thermic effect of feeding (~10%), and nonresting energy expenditure (10%-40%).5 Whether total energy expenditure is reduced beyond the level expected for a given reduction in the size of the metabolizing mass following calorie restriction is debated. Leibel et al6 showed that a 10% weight loss reduced sedentary 24-hour energy intake for weight maintenance between 15% and 20% in obese patients, suggesting that metabolic adaptation occurs in humans. However, the weight loss was achieved quickly with a liquid diet and, with the exception of several normal-weight patients in the study by Leibel et al, the effects of prolonged calorie restriction on energy expenditure in nonobese humans have not been assessed. In rhesus monkeys, resting energy expenditure adjusted for fat-free mass (FFM) and fat mass was lower after 11 years of calorie restriction.7 Similarly, total energy expenditure was lower in monkeys following 10 years of weight clamping.8 Studies in rodents have proven more controversial with reports of decreased, no change, or increased adjusted energy expenditure in calorie restriction vs ad libitum fed–animals.9- 13
One of the most widely accepted theories of aging is the oxidative stress theory, which hypothesizes that oxidative damage produced by ROS accumulates over time, leading to the development of disease such as cancer, aging, and ultimately death.14 Reactive oxygen species are byproducts of energy metabolism, with 0.2% to 2.0% of oxygen consumption (O2) resulting in ROS formation.15- 16 Reactive oxygen species attack lipids, proteins, and DNA, generating a number of products that affect normal cell functioning.17 Studies in rodents subjected to calorie restriction demonstrate a 30% decrease in 8-oxo-7,8-dihydroguanine (8-oxodG) in brain, skeletal muscle, and heart; similar reductions in carbonyl content in brain and muscle18- 22; and transcriptional patterns that suggest decreased oxidative stress in response to calorie restriction.23 Rhesus monkeys subjected to calorie restriction exhibit divergent responses in the expression of genes involved in oxidative stress.24
Core body temperature and levels of dehydroepiandrosterone sulfate (DHEAS) and insulin are proposed biomarkers of calorie restriction and longevity in rodents and monkeys.25 Data from the Baltimore Longitudinal Study of Aging support the association between longevity and temperature and insulin and DHEAS levels; men with plasma insulin concentration or oral temperature below the median, and DHEAS levels above the median, live longer.26 Furthermore, in a cross-sectional study that compared individuals following self-imposed nutritionally adequate calorie restriction for 6 years with normal-weight controls, Fontana et al27 found that participants in the calorie restriction group had lower levels of serum glucose, insulin, and markers of atherosclerosis.
The aims of this study were to establish whether prolonged calorie restriction by diet alone or in conjunction with exercise can be successfully implemented in nonobese individuals and to determine the effects of the interventions on established biomarkers of calorie restriction, sedentary energy expenditure, and oxidative damage to DNA and proteins.
Full-text · Article · · JAMA The Journal of the American Medical Association