Energetics of obesity and weight control: does diet composition matter?

Greater Loss of Central Adiposity from Low-Carbohydrate versus Low-Fat Diet in Middle-Aged Adults with Overweight and Obesity

The objective of this study is to determine whether middle-aged adults prescribed a low carbohydrate-high fat (LCHF) or low fat (LF) diet would have greater loss of central fat and to determine whether the insulin resistance (IR) affects intervention response. A total of 50 participants (52.3 ± 10.7 years old; 36.6 ± 7.4 kg/m2 BMI; 82% female) were prescribed either a LCHF diet (n = 32, carbohydrate: protein: fat of 5%:30%:65% without calorie restriction), or LF diet (n = 18, 63%:13–23%: 10–25% with calorie restriction of total energy expenditure—500 kcal) for 15 weeks. Central and regional body composition changes from dual-x-ray absorptiometry and serum measures were compared using paired t-tests and ANCOVA with paired contrasts. IR was defined as homeostatic model assessment (HOMA-IR) > 2.6. Compared to the LF group, the LCHF group lost more android (15.6 ± 11.2% vs. 8.3 ± 8.1%, p < 0.01) and visceral fat (18.5 ± 22.2% vs. 5.1 ± 15.8%, p < 0.05). Those with IR lost more android and visceral fat on the LCHF verses LF group (p < 0.05). Therefore, the clinical prescription to a LCHF diet may be an optimal strategy to reduce disease risk in middle-aged adults, particularly those with IR.

Basal Metabolic Rate and Body Composition Predict Habitual Food and Macronutrient Intakes: Gender Differences

The underlying mechanisms that regulate energy homeostasis and food intake are not fully understood. Moreover, little research has been performed on the relation of body composition with habitual macronutrient intake among free-living populations. Since body composition and energy metabolism differ between males and females, we aimed to determine whether the relationship between body composition and habitual macronutrient intakes is gender-dependent. In this cross-sectional study, 261 participants (99 males) were recruited from Singapore. Macronutrient intake was evaluated from a three-day self-reported dietary record. Body composition and basal metabolic rate (BMR) were determined by using dual-energy X-ray absorptiometry (DEXA) and indirect calorimetry, respectively. Our results show that both BMR (p < 0.001) and lean body mass (LBM, p < 0.001) predicted daily energy intake (EI). LBM was positively associated with intakes of protein (PRO) and fat (FAT) in females, but not in males. This relationship persisted even after adjustment for fat mass (FM). On the other hand, no significant associations between FM and macronutrient intake were observed in both males and females. Therefore, the relationship between habitual macronutrient intake, LBM, and BMR is gender-dependent. Elucidating the gender differences in energy metabolism is important for understanding the factors that regulate energy homeostasis and can subsequently help better manage energy balance.

Perceived Family Functioning in Relation to Energy Intake in Adolescent Girls with Loss of Control Eating

Family functioning is hypothesized to influence the development, maintenance, and treatment of obesity and eating disorders. However, there are limited data examining family functioning in relation to energy intake in the laboratory among youth at high-risk for eating disorders and excess weight gain. Therefore, we examined the relationship between perceived family functioning and energy intake during a laboratory test meal designed to model a binge episode. We performed hierarchical multiple regression analyses among 108 adolescent girls in an excess weight gain prevention trial. Participants were at high-risk for eating disorders and excess weight gain due to reports of loss of control eating (LOC) and high body mass index (BMI). Participants completed the Family Adaptability and Cohesion Scale III to assess family adaptability and cohesion. Following an overnight fast, girls consumed lunch from a laboratory test meal. Poorer family adaptability, but not cohesion, was associated with lower percentage of total energy intake from protein and greater percentage of total energy intake from carbohydrates. Neither adaptability nor cohesion were significantly associated with total intake. We conclude that among girls with LOC eating and high BMI, poor reported family adaptability is associated with greater consumption of obesity-promoting macronutrients during binge episodes. Directionality and temporality of this association between unhealthy consumption and family rigidity requires further study.

Effects of High Protein and Balanced Diets on Lipid Profiles and Inflammation Biomarkers in Obese and Overweight Women at Aerobic Clubs: A Randomized Clinical Trial

BACKGROUND

We studied the effects of high protein (HP) and balanced diets (BDs) on lipid profiles, and high-sensitive C-reactive protein (hs-CRP) levels in obese and overweight women.

METHODS

In a parallel designed randomized controlled clinical trial, 60 healthy women with body mass index ≥25 kg/m², aged 20-46 years, enrolled in an 8-week investigation at aerobic clubs. They were categorized into two groups (HP and BDs), randomly. Fasting lipid profile and hs-CRP levels were evaluated at the beginning and end of the trial. We assessed dietary intake by 3-day records and also used SPSS (version 18; SPSS Inc., Chicago, IL, USA) for data analyzing.

RESULTS

Fifty-six participants completed the intervention. Concentrations of low-density lipoprotein cholesterol (P < 0.001 in BD group vs. P =0.023 in HP group) and high-density lipoprotein cholesterol (P < 0.001 in BD group vs. P =0.002 in HP group) increased significantly in both groups. Circulating triglycerides levels increased in both intervention grows, but the change in the HP group was not significant compared with the other group (P = 0.007 in BD group vs. P =0.099 in HP group). Whereas total cholesterol concentration decreased but not significantly so (P = 0.53 in BD group vs. P =0.73 in HP group). There were marginally significant decreases in the hs-CRP levels due to both diets (P = 0.057 in BD group vs. P =0.086 in HP group); however, there were no significant differences between the groups.

CONCLUSIONS

Administration of HP and BD in overweight and obese women with regular aerobic exercise showed improvement in lipid profiles and hs-CRP levels within the groups, but there were no significant differences between groups.

Higher Dietary Choline and Betaine Intakes Are Associated with Better Body Composition in the Adult Population of Newfoundland, Canada

Background

Choline is an essential nutrient and betaine is an osmolyte and methyl donor. Both are important to maintain health including adequate lipid metabolism. Supplementation of dietary choline and betaine increase muscle mass and reduce body fat in animals. However, little data is available regarding the role of dietary choline and betaine on body composition in humans.

Objective

To investigate the association between dietary choline and betaine intakes with body composition in a large population based cross-sectional study.

Design

A total of 3214 subjects from the CODING (Complex Disease in Newfoundland population: Environment and Genetics) study were assessed. Dietary choline and betaine intakes were computed from the Willett Food Frequency questionnaire. Body composition was measured using dual-energy X-ray absorptiometry following a 12-hour fast. Major confounding factors including age, sex, total calorie intake and physical activity level were controlled in all analyses.

Result

Significantly inverse correlations were found between dietary choline and betaine intakes, with all obesity measurements: total percent body fat (%BF), percent trunk fat (%TF), percent android fat (%AF), percent gynoid fat (%GF) and anthropometrics: weight, body mass index, waist circumference, waist-to-hip ratio in both women and men (r range from -0.13 to -0.47 for choline and -0.09 to -0.26 for betaine, p<0.001 for all). Dietary choline intake had stronger association than betaine. Moreover, obese subjects had the lowest dietary choline and betaine intakes, with overweight subjects in the middle, and normal weight subjects consumed the highest dietary choline and betaine (p<0.001). Vice versa, when subjects were ranked according to dietary choline and betaine intakes, subjects with the highest intake of both had the lowest %TF, %AF, %GF, %BF and highest %LM among the groups in both sexes.

Conclusion

Our findings indicate that high dietary choline and betaine intakes are significantly associated with favorable body composition in humans.

Impact of Weight Loss on Plasma Leptin and Adiponectin in Overweight-to-Obese Post Menopausal Breast Cancer Survivors

Women who are obese at the time of breast cancer diagnosis have higher overall mortality than normal weight women and some evidence implicates adiponectin and leptin as contributing to prognostic disadvantage. While intentional weight loss is thought to improve prognosis, its impact on these adipokines is unclear. This study compared the pattern of change in plasma leptin and adiponectin in overweight-to-obese post-menopausal breast cancer survivors during weight loss. Given the controversies about what dietary pattern is most appropriate for breast cancer control and regulation of adipokine metabolism, the effect of a low fat versus a low carbohydrate pattern was evaluated using a non-randomized, controlled study design. Anthropometric data and fasted plasma were obtained monthly during the six-month weight loss intervention. While leptin was associated with fat mass, adiponectin was not, and the lack of correlation between leptin and adiponectin concentrations throughout weight loss implies independent mechanisms of regulation. The temporal pattern of change in leptin but not adiponectin was affected by magnitude of weight loss. Dietary pattern was without effect on either adipokine. Mechanisms not directly related to dietary pattern, weight loss, or fat mass appear to play dominant roles in the regulation of circulating levels of these adipokines.

Decreasing cardiovascular risk factors in obese individuals using a combination of PGX® meal replacements and PGX® granules in a 12-week clinical weight modification program

In this open, clinically based, weight modification program, we determined in six sedentary obese adults (five women; one male; age range 30-62 years) that the combination of a modified calorie diet plus PGX® meal replacement and PGX® supplementation resulted in a significant reduction in several cardiovascular risk factors over a 12-week time period. This included a significant improvement in lipids (-0.98 mmol/l LDL-C), reduction in average weight (-9.2 kg), mean reduction in fat (-4.1%) and an increase in fat-free mass (2.8%).

A well-balanced diet combined or not with exercise induces fat mass loss without any decrease of bone mass despite bone micro-architecture alterations in obese rat

The association of a well-balanced diet with exercise is a key strategy to treat obesity. However, weight loss is linked to an accelerated bone loss. Furthermore, exercise is known to induce beneficial effects on bone. We investigated the impact of a well-balanced isoenergetic reducing diet (WBR) and exercise on bone tissue in obese rats. Sixty male rats had previously been fed with a high fat/high sucrose diet (HF/HS) for 4months to induce obesity. Then, 4 regimens were initiated for 2months: HF/HS diet plus exercise (treadmill: 50min/day, 5days/week), WBR diet plus exercise, HF/HS diet plus inactivity and WBR diet plus inactivity. Body composition and total BMD were assessed using DXA and visceral fat mass was weighed. Tibia densitometry was assessed by Piximus. Bone histomorphometry was performed on the proximal metaphysis of tibia and on L2 vertebrae (L2). Trabecular micro-architectural parameters were measured on tibia and L2 by 3D microtomography. Plasma concentration of osteocalcin and CTX were measured. Both WBR diet and exercise had decreased global weight, global fat and visceral fat mass (p<0.05). The WBR diet alone failed to alter total and tibia bone mass and BMD. However, Tb.Th, bone volume density and degree of anisotropy of tibia were decreased by the WBR diet (p<0.05). Moreover, the WBR diet had involved a significant lower MS/BS and BFR/BS in L2 (p<0.05). Exercise had significantly improved BMD of the tibia possibly by inhibiting the bone resorption, as evidenced by no change in plasma osteocalcin levels, a decrease of CTX levels (p<0.005) and trabecular osteoclast number (p<0.05). In the present study a diet inducing weight and fat mass losses did not affected bone mass and BMD of obese rats despite alterations of their bone micro-architecture. The moderate intensity exercise performed had improved the tibia BMD of obese rats without any trabecular and cortical adaptation.

Effect of diet composition and weight loss on resting energy expenditure in the POUNDS LOST study

Weight loss reduces energy expenditure, but it is unclear whether dietary macronutrient composition affects this reduction. We hypothesized that energy expenditure might be modulated by macronutrient composition of the diet. The Prevention of Obesity Using Novel Dietary Strategies (POUNDS) LOST study, a prospective, randomized controlled trial in 811 overweight/obese people who were randomized in a 2 × 2 design to diets containing 20en% or 40en% fat and 15en% or 25en% protein (diets with 65%, 55%, 45%, and 35% carbohydrate) provided the data to test this hypothesis. Resting energy expenditure (REE) was measured at baseline, 6, and 24 months using a ventilated hood. REE declined at 6 months by 99.5 ± 8.0 kcal/day in men and 55.2 ± 10.6 kcal/day in women during the first 6 months. This decline was related to the weight loss, and there was no difference between the diets. REE had returned to baseline by 24 months, but body weight was still 60% below baseline. Measured REE at 6 months was significantly lower than the predicted (-18.2 ± 6.7 kcal/day) and was the result of significant reductions from baseline in the low-fat diets (65% or 55% carbohydrate), but not in the high fat diet groups. By 24 months the difference had reversed with measured REE being slightly but significantly higher than predicted (21.8 ± 10.1 kcal/day). In conclusion, we found that REE fell significantly after weight loss but was not related to diet composition. Adaptive thermogenesis was evident at 6 months, but not at 24 months.

Small changes in meal patterns lead to significant changes in total caloric intake. Effects of diet and social status on food intake in female rhesus monkeys

Social subordination in macaques is a well-established model to study the adverse effects of psychosocial stress on a number of health outcomes, including stress-induced eating. The present analysis was conducted to empirically define a meal among free-feeding female rhesus monkeys and to examine the roles of meal patterning (e.g., meal size, meal frequency, and snacking patterns) in findings from a previous study demonstrating that psychosocial stress increases overall caloric intake among subordinate animals with access to a highly palatable diet. Results indicate that all animals, regardless of social status, consumed more frequent meals, larger meals, and more calories in the form of snacks when a highly palatable diet was available. Additional findings suggest that subordinate animals consumed significantly larger meals compared to their dominant counterparts regardless of the dietary environment. Additionally, subordinate females with a history of exposure to the palatable diet consumed significantly more snack calories than both dominant and subordinate animals without previous exposure to the palatable diet when these females were returned to a standard laboratory diet. These findings illustrate how small changes in meal patterns can lead to significant increases in total caloric intake, which if prolonged, could promote the emergence of an obese phenotype.

Popcorn is more satiating than potato chips in normal-weight adults

BACKGROUND

Strategies that may increase compliance to reduced energy intakes are needed to reduce the health burden of obesity. Conflicting evidence exists regarding the effects of snacking on satiety and energy intake.

METHODS

This study compared short-term satiety from two common snack foods, low fat popcorn or potato chips. Using a counterbalanced within-subject design, 35 normal weight non-smoking participants (17 men, 18 women) ages 20-50 years (mean age 33 ± 11, BMI 23 ± 2 kg/m²) consumed four conditions each: 200 mL of water (control), one cup (4 g, 15 kcal) popcorn, 6 cups (27 g, 100 kcal) popcorn, and one cup (28 g, 150 kcal) potato chips, each with 200 mL water. Participants rated their hunger, satisfaction, prospective consumption, and thirst on 100 mm visual analogue scales 30 minutes after commencement of snack consumption. In addition, post-snack energy intake from an ad libitum meal (amount served less amount remaining) was measured, and the test food and meal combined energy intake and energy compensation were calculated.

RESULTS

Participants expressed less hunger, more satisfaction, and lower estimates of prospective food consumption after six cups of popcorn compared to all other treatments (P < 0.05). Energy compensation was 220% ± 967%, 76% ± 143% and 42% ± 75% after one cup popcorn, six cups popcorn and one cup potato chips, respectively. Combined energy intake was significantly greater (P < 0.01) during the potato chips condition (803 ± 277 kcal) compared to control (716 ± 279 kcal) or popcorn conditions (698 ± 286 kcal for one cup and 739 ± 294 kcal for six cups). Combined energy intakes from both popcorn conditions were not significantly different than control (p > 0.05).

CONCLUSION

Popcorn exerted a stronger effect on short-term satiety than did potato chips as measured by subjective ratings and energy intake at a subsequent meal. This, combined with its relatively low calorie load, suggests that whole grain popcorn is a prudent choice for those wanting to reduce feelings of hunger while managing energy intake and ultimately, body weight.

Dietary protein in weight management: a review proposing protein spread and change theories

A large volume of human clinical data supports increased dietary protein for favorable changes to body composition, but not all data are conclusive. The aim of this review is to propose two theories, "protein spread theory" and "protein change theory" in an effort to explain discrepancies in the literature. Protein spread theory proposed that there must have been a sufficient spread or % difference in g/kg/day protein intake between groups during a protein intervention to see body composition and anthropometric differences. Protein change theory postulated that for the higher protein group, there must be a sufficient change from baseline g/kg/day protein intake to during study g/kg/day protein intake to see body composition and anthropometric benefits. Fifty-one studies met inclusion criteria. In studies where a higher protein intervention was deemed successful there was, on average, a 58.4% g/kg/day between group protein intake spread versus a 38.8% g/kg/day spread in studies where a higher protein diet was no more effective than control. The average change in habitual protein intake in studies showing higher protein to be more effective than control was +28.6% compared to +4.9% when additional protein was no more effective than control. Providing a sufficient deviation from habitual intake appears to be an important factor in determining the success of additional protein in weight management interventions. A modest increase in dietary protein favorably effects body composition during weight management interventions.

Effects of fat, protein, and carbohydrate and protein load on appetite, plasma cholecystokinin, peptide YY, and ghrelin, and energy intake in lean and obese men

While protein is regarded as the most satiating macronutrient, many studies have employed test meals that had very high and unsustainable protein contents. Furthermore, the comparative responses between lean and obese subjects and the relationships between energy intake suppression and gut hormone release remain unclear. We evaluated the acute effects of meals with modest variations in 1) fat, protein, and carbohydrate content and 2) protein load on gastrointestinal hormones, appetite, and subsequent energy intake in lean and obese subjects. Sixteen lean and sixteen obese men were studied on four occasions. Following a standardized breakfast, they received for lunch: 1) high-fat (HF), 2) high-protein (HP), 3) high-carbohydrate/low-protein (HC/LP), or 4) adequate-protein (AP) isocaloric test meals. Hunger, fullness, and gut hormones were measured throughout, and at t = 180 min energy intake at a buffet meal was quantified. In lean subjects, hunger was less and fullness greater following HF, HP, and AP compared with HC/LP meals, and energy intake was less following HF and HP compared with HC meals (P < 0.05). In the obese subjects, hunger was less following HP compared with HF, HC/LP, and AP meals, and energy intake was less following HP and AP compared with HF and HC meals (P < 0.05). There were no major differences in hormone responses to the meals among subject groups, but the CCK and ghrelin responses to HP and AP were sustained in both groups. In conclusion, HP meals suppress energy intake in lean and obese subjects, an effect potentially mediated by CCK and ghrelin, while obese individuals appear to be less sensitive to the satiating effects of fat.

Modeling metabolic adaptations and energy regulation in humans

Mathematical modeling of human energy regulation and body weight change has recently reached the level of sophistication required for accurate predictions. Mathematical models are beginning to provide a quantitative framework for integrating experimental data in humans and thereby help us better understand the dynamic imbalances of energy and macronutrients that give rise to changes in body weight and composition. This review provides an overview of the various approaches that have been used to model body weight dynamics and energy regulation in humans, highlights several insights that these models have provided, and suggests how mathematical models can serve as a guide for future experimental research.

Effect of diet composition on energy expenditure during weight loss: the POUNDS LOST Study

BACKGROUND

Weight loss reduces energy expenditure, but the contribution of different macronutrients to this change is unclear.

HYPOTHESIS

We tested the hypothesis that macronutrient composition of the diet might affect the partitioning of energy expenditure during weight loss.

DESIGN

A substudy of 99 participants from the Preventing Overweight Using Novel Dietary Strategies (POUNDS LOST) trial had total energy expenditure (TEE) measured by doubly labeled water, and resting energy expenditure (REE) measured by indirect calorimetry at baseline and repeated at 6 months in 89 participants. Participants were randomly assigned to one of four diets with either 15 or 25% protein and 20 or 40% fat.

RESULTS

TEE and REE were positively correlated with each other and with fat-free mass and body fat, at baseline and 6 months. The average weight loss of 8.1 ± 0.65 kg (least-square mean ± s.e.) reduced TEE by 120 ± 56  kcal per day and REE by 136 ± 18 kcal per day. A greater weight loss at 6 months was associated with a greater decrease in TEE and REE. Participants eating the high-fat diet (HF) lost significantly more fat-free mass (1.52 ± 0.55 kg) than the low-fat (LF) diet group (P<0.05). Participants eating the LF diet had significantly higher measures of physical activity than the HF group.

CONCLUSION

A greater weight loss was associated with a larger decrease in both TEE and REE. The LF diet was associated with significant changes in fat-free body mass and energy expenditure from physical activity compared with the HF diet.

The dietary treatment of obesity

In no sector of therapeutics is the theory so simple as in weight control. The major gap lies in translating this theory into practice. In the final analysis, the answer lies in personal choice, because many diets seem to work, but not universally in all studies. A reduced calorie diet is obviously essential, although the composition remains to be individually tailored. For this, health care professionals must become “personal trainers” and realize the importance of lifestyle prescriptions with regard to diet and exercise in all consultations, fitting them to the needs of patient. It may be argued that medical practitioners do not have the necessary time or behavioral skills for these long-term interventions, which might be better handled by a team of other health professionals. Prevention is, of course, better than treatment, and therefore a major effort must be made to target children, from breast feeding to education throughout schooling. No more surveys are needed; “we know the enemy and it is us.” In the words of the Lancet editorial concerning obesity: “Our public health leaders must replace prevarication with imagination.”

Quantification of the effect of energy imbalance on bodyweight

Obesity interventions can result in weight loss, but accurate prediction of the bodyweight time course requires properly accounting for dynamic energy imbalances. In this report, we describe a mathematical modelling approach to adult human metabolism that simulates energy expenditure adaptations during weight loss. We also present a web-based simulator for prediction of weight change dynamics. We show that the bodyweight response to a change of energy intake is slow, with half times of about 1 year. Furthermore, adults with greater adiposity have a larger expected weight loss for the same change of energy intake, and to reach their steady-state weight will take longer than it would for those with less initial body fat. Using a population-averaged model, we calculated the energy-balance dynamics corresponding to the development of the US adult obesity epidemic. A small persistent average daily energy imbalance gap between intake and expenditure of about 30 kJ per day underlies the observed average weight gain. However, energy intake must have risen to keep pace with increased expenditure associated with increased weight. The average increase of energy intake needed to sustain the increased weight (the maintenance energy gap) has amounted to about 0·9 MJ per day and quantifies the public health challenge to reverse the obesity epidemic.

Protein choices targeting thermogenesis and metabolism

BACKGROUND

Dietary proteins stimulate thermogenesis and satiety more than does carbohydrate or fat; however, less is known about the differences between protein sources.

OBJECTIVE

The objective was to determine the differential effects of 3 proteins on energy metabolism, satiety, and glucose control.

DESIGN

Energy metabolism, satiety, and glucose control were measured in 23 lean, healthy subjects on separate occasions, before and 5.5 h after consumption of 4 isocaloric test meals in a randomized, double-blind, crossover design. Three meals consisting of 50% protein (whey, casein, or soy), 40% carbohydrate, and 10% fat and a fourth meal consisting of 95.5% carbohydrate were compared with a glucose meal that provided the same glucose load as the protein meals.

RESULTS

The thermic effect was greater after the whey (14.4 ± 0.5%) than after the casein (12.0 ± 0.6%; P = 0.002) and soy (11.6 ± 0.5%; P = 0.0001) meals and was greater after the whey, casein, and soy meals than after the high-carbohydrate meal (6.6 ± 0.5%; P < 0.0001). Cumulative fat oxidation tended to be greater after the whey meal (16.2 ± 1.1 g) than after the soy meal (13.7 ± 1.0 g; P = 0.097) and was greater after the whey and soy meals than after the high-carbohydrate meal (10.9 ± 0.9 g; P < 0.05). The glycemic response to glucose was attenuated 32% by the proteins (P < 0.001) at the expense of a greater insulin response after whey than after glucose (154%; P = 0.02), casein (143%; P = 0.07), and soy (151%; P = 0.03). Subjective appetite sensations indicated that casein and soy were more satiating than whey (P < 0.01), but whey was more "liked" compared with casein and soy (P = 0.025 and P = 0.09, respectively).

CONCLUSION

The results suggest that different protein sources could be used to modulate metabolism and subsequently energy balance.

Development of satiating and palatable high-protein meat products by using experimental design in food technology

BACKGROUND AND OBJECTIVES

Foods high in protein are known to satiate more fully than foods high in other constituents. One challenge with these types of food is the degree of palatability. This study was aimed at developing the frankfurter style of sausages that would regulate food intake as well as being the preferred food choice of the consumer.

DESIGN AND MEASURES

16 sausage varieties with commercial (PE% 20) or higher amount of protein (PE% 40), being modified with vegetable fat (3% of rapeseed oil), and smoked or not, underwent a sensory descriptive analysis, in which the information was used to choose a subsample of four sausages for a satiety test. Twenty-seven subjects were recruited based on liking and frequency of sausage consumption. The participants ranged in age from 20 to 28, and in body mass index (BMI) between 19.6 and 30.9. The students were served a sausage meal for five consecutive days and then filled out a questionnaire to describe their feelings of hunger, satiety, fullness, desire to eat an their prospective consumption on a visual analogue scale (VAS) starting from right before, right after the meal, every half hour for 4 h until the next meal was served, and right after the second meal.

RESULTS AND CONCLUSION

The higher protein sausages were less juicy, oily, fatty, adhesive, but harder and more granular than with lower amount of protein. The high-protein sausages were perceived as more satiating the first 90 min after the first meal. Some indication of satiety effect of added oil versus meat fat. No significant differences in liking among the four sausage varieties.

Pulse consumption, satiety, and weight management

The prevalence of obesity has reached epidemic proportions, making finding effective solutions to reduce obesity a public health priority. One part of the solution could be for individuals to increase consumption of nonoilseed pulses (dry beans, peas, chickpeas, and lentils), because they have nutritional attributes thought to benefit weight control, including slowly digestible carbohydrates, high fiber and protein contents, and moderate energy density. Observational studies consistently show an inverse relationship between pulse consumption and BMI or risk for obesity, but many do not control for potentially confounding dietary and other lifestyle factors. Short-term (≤1 d) experimental studies using meals controlled for energy, but not those controlled for available carbohydrate, show that pulse consumption increases satiety over 2-4 h, suggesting that at least part of the effect of pulses on satiety is mediated by available carbohydrate amount or composition. Randomized controlled trials generally support a beneficial effect of pulses on weight loss when pulse consumption is coupled with energy restriction, but not without energy restriction. However, few randomized trials have been conducted and most were short term (3-8 wk for whole pulses and 4-12 wk for pulse extracts). Overall, there is some indication of a beneficial effect of pulses on short-term satiety and weight loss during intentional energy restriction, but more studies are needed in this area, particularly those that are longer term (≥1 y), investigate the optimal amount of pulses to consume for weight control, and include behavioral elements to help overcome barriers to pulse consumption.

Protein metabolic roles in treatment of obesity

PURPOSE OF REVIEW

To understand the potential benefits of increased dietary protein during weight loss and the importance of distribution of high-quality protein at each meal.

RECENT FINDINGS

Popular weight loss diets emphasize use of protein as a substitute for carbohydrates or fat to reduce insulin and minimize hunger and food cravings. These diets produce short-term weight loss, but long-term benefits remain obscured by failure to differentiate between outcomes of subject compliance and diet effectiveness. New molecular mechanisms have defined the benefits of protein as a meal threshold for the branched-chain amino acid leucine, which has been characterized as a unique signal regulator of muscle protein synthesis. Leucine consumed at 2.5 g triggers a postmeal anabolic response that protects metabolic active tissues during weight loss and increases loss of body fat.

SUMMARY

Balanced daily distribution of protein with increased intake at breakfast and lunch protects metabolically active tissues including skeletal muscle during weight loss.

The energetics of obesity: a review: monitoring energy intake and energy expenditure in humans

Writing about obesity research is a challenging task. While the rising obesity epidemic drastically raised public awareness of the problem, the causes behind the epidemic are still poorly understood. The etiology of obesity is a subject of ongoing scientific debate with widely varying views and strong opinions. Is it mostly genetic or environmental in nature? Is obesity caused by changes in our diet or changes in lifestyle and physical activity or both? Modern research literature quite often offers conflicting findings. Publications in popular media like the one in Time magazine add to the controversy by making quick and strongly worded summaries of academic research. Although the root causes of obesity remains a topic of active research, this review concentrates on the fundamental components of weight regulation in humans and their relative contribution to the energy equation. A better understanding of the energetics of obesity may provide some insight into the etiology of the obesity epidemic. The energetics of obesity also showcases an engineering challenge: development of techniques to accurately measure individual components of the energy equation.

Higher Dietary Protein Intake is Associated with Lower Body Fat in the Newfoundland Population

BACKGROUND

Increased protein proportions in the diet combined with energy restriction has been shown to enhance weight loss during dietary intervention. It is not known if the beneficial effect of dietary protein exists in the general population under normal living conditions without a negative energy balance.

METHODS

A total of 1834 participants (n = 443 men, n = 1391 women) were recruited from the CODING study. Participants' dietary macronutrient compositions were determined through a Willett FFQ. Body composition variables including percent body fat (%BF), percent trunk fat (%TF), percent total lean mass (%LM), and percent trunk lean mass (%TLM) were determined using DXA. Major confounding factors including age, physical activity levels, total caloric intake, carbohydrate intake, menopausal status, smoking status and medication use were controlled for in all analyses.

RESULTS

Significant inverse relationships were observed between dietary protein intake (g/kg body weight/day) and weight, waist circumference, waist-to-hip ratio, BMI, %BF, and %TF (P < 0.001). Significant positive relationships were observed with %LM and %TLM (P < 0.001). Additionally, significant differences in weight (12.7 kg in men, 11.4 kg in women), BMI (4.1 BMI units in men, 4.2 units in women), and %BF (7.6% in men, 6.0% in women) were observed between low and high dietary protein consuming groups (P < 0.001). Dietary protein explained 11% of the total variation in %BF in the NL population.

CONCLUSION

This study provides strong evidence that higher protein intake, even in the absence of energy restriction, is associated with a more favorable body composition in the general population.

Low or moderate dietary energy restriction for long-term weight loss: what works best?

Theoretical calculations suggest that small daily reductions in energy intake can cumulatively lead to substantial weight loss, but experimental data to support these calculations are lacking. We conducted a 1-year randomized controlled pilot study of low (10%) or moderate (30%) energy restriction (ER) with diets differing in glycemic load in 38 overweight adults (mean +/- s.d., age 35 +/- 6 years; BMI 27.6 +/- 1.4 kg/m(2)). Food was provided for 6 months and self-selected for 6 additional months. Measurements included body weight, resting metabolic rate (RMR), adherence to the ER prescription assessed using (2)H(2)(18)O, satiety, and eating behavior variables. The 10%ER group consumed significantly less energy (by (2)H(2)(18)O) than prescribed over 12 months (18.1 +/- 9.8%ER, P = 0.04), while the 30%ER group consumed significantly more (23.1 +/- 8.7%ER, P < 0.001). Changes in body weight, satiety, and other variables were not significantly different between groups. However, during self-selected eating (6-12 months) variability in % weight change was significantly greater in the 10%ER group (P < 0.001) and poorer weight outcome on 10%ER was predicted by higher baseline BMI and greater disinhibition (P < 0.0001; adj R(2) = 0.71). Weight loss at 12 months was not significantly different between groups prescribed 10 or 30%ER, supporting the efficacy of low ER recommendations. However, long-term weight change was more variable on 10%ER and weight change in this group was predicted by body size and eating behavior. These preliminary results indicate beneficial effects of low-level ER for some but not all individuals in a weight control program, and suggest testable approaches for optimizing dieting success based on individualizing prescribed level of ER.

Nutritional treatment of obesity

The focus of this article is nutritional strategies for weight loss. Following a review of general nutritional principles, the evidence behind specific nutritional weight-loss strategies is presented. These strategies include nutritional supplements, nutrient-limited diets, and energy-limited diets. A brief discussion of nutritional considerations relevant to other weight-loss strategies--pharmacologic, surgical, and exercise-based--is included. Specific evidence-based recommendations are presented.

Effects of two energy-restricted diets differing in the carbohydrate/protein ratio on weight loss and oxidative changes of obese men

INTRODUCTION

Low-carbohydrate, high-protein diets are a current challenge in the nutritional treatment of obesity.

OBJECTIVE

To compare the effect of a low-carbohydrate high-protein diet with a traditional hypocaloric diet on weight loss and mitochondrial oxidative metabolism.

SUBJECTS AND METHODS

Nineteen obese men (age 36+/-6 years; body mass index 34+/-2 kg/m2) were randomized to follow one of the two diets-control diet (15% protein; 30% lipids; 55% carbohydrates) or high-protein diet (30% protein; 30% lipids; 40% carbohydrates)-over an 8-week period. Anthropometry, biochemical variables, resting energy expenditure and mitochondrial oxidation were measured at the start and at the end of the intervention.

RESULTS

The high-protein diet produced a greater weight loss (-8.3+/-1.2% versus -5.5+/-2.5%, P = 0.012) than the control diet. Interestingly, an activation in the mitochondrial oxidation was found in the high-protein-fed group. This stimulation was positively correlated with the final resting energy expenditure and negatively associated with the final fat mass content.

CONCLUSION

Low-carbohydrate high-protein diets could involve specific changes in mitochondrial oxidation that could be related to a higher weight loss.

Reduced body weight and adiposity with a high-protein diet improves functional status, lipid profiles, glycemic control, and quality of life in patients with heart failure: a feasibility study

BACKGROUND

The effectiveness of high-protein (HP) diets in reducing body weight and adiposity and potentially improving clinical outcomes in heart failure (HF) is not known.

OBJECTIVE

This feasibility study was conducted to evaluate the impact of 3 dietary interventions on body weight and adiposity, functional status, lipid profiles, glycemic control, and quality of life (QOL) in overweight and obese patients with HF and type 2 diabetes mellitus.

DESIGN

Fourteen patients with HF with a body mass index greater than 27 kg/m2 were randomized to an HP diet, a standard protein diet, or a conventional diet. Data were obtained at baseline and 12 weeks.

RESULTS

There were no significant differences in age (59 +/- 10 years), sex (78% male), New York Heart Association class (43% class II, 57% class III), and HF etiology or left ventricular ejection fraction (26 +/- 7) between the groups at baseline. Patients on the HP diet demonstrated significantly greater reductions in weight (P = .005), percent body fat (P = .036), total cholesterol (P = .016), triglyceride concentrations (P = .034), and low-density lipoprotein cholesterol (P = .041) and greater improvements in functional status (6-minute walk [P = .010] and VO2 peak [P = .003]), high-density lipoprotein cholesterol (P = .006), and physical QOL scores (P = .022) compared with those on standard protein and conventional diets.

CONCLUSION

A 12-week HP diet resulted in moderate weight loss and reduced adiposity in a small sample of overweight and obese patients with HF that were associated with improvements in functional status, lipid profiles, glycemic control, and QOL. However, these preliminary findings must be confirmed in studies with more participants and long-term follow-up.

Moderate-carbohydrate low-fat versus low-carbohydrate high-fat meal replacements for weight loss

OBJECTIVES

To compare the efficacy of a low-carbohydrate high-fat versus a moderate-carbohydrate low-fat diet for weight loss and cardiovascular risk reduction.

METHODS

In a prospective clinical trial, 137 participants (body mass index >or=25 kg/m2) were randomly assigned to Control (46 randomized, 44 completed), Low Carbohydrate (45 randomized, 42 completed), or Moderate Carbohydrate (46 randomized, 40 completed) groups. Outcomes included measures of body size and composition and blood chemistries.

RESULTS

Both the Low and Moderate Carbohydrate groups lost significantly more weight as well as inches from their waists and thighs than the Control group, while the Low Carbohydrate group lost a greater percentage of body fat. Although the Moderate Carbohydrate group showed significant reductions in serum cholesterol, the Low Carbohydrate group showed the greatest improvements in serum cholesterol, triglycerides, high-density lipoprotein, low-density lipoprotein, and very-low-density lipoprotein.

CONCLUSIONS

Moderate approaches to weight loss such as a moderate-carbohydrate low-fat diet may be prudent.

The long-term influence of orlistat on dietary intake in obese subjects with components of metabolic syndrome

BACKGROUND

Orlistat is a lipase inhibitor that reduces the intestinal absorption of fat and may enhance the effects of dietary and behavioural therapy on weight loss and maintenance. The present study examined the effect of orlistat on dietary intake, especially fat intake, during long-term weight maintenance.

METHODS

Subjects comprised 44 men and women (aged 18-63 years; body mass index 37.5 +/- 4.3 kg m(-2)) included in the Scandinavian Multicenter study of Obese subjects with the metabolic syndrome, a 3-year clinical trial of orlistat or placebo following an 8-week, very low energy diet (VLED). Two months after the end of the trial when the use of orlistat was optional, 33 subjects remained in the study. A dietary interview based on a validated food frequency questionnaire was conducted before the VLED, after 1 year of treatment with orlistat or placebo and 2 months after the end of the trial.

RESULTS

At 1 year, dietary intake did not differ between the orlistat and placebo group. Energy percent (E%) fat was reduced and E% carbohydrate was increased within both groups. Two months after the end of the trial, E% fat was 32.6% (SD 6.2%) in subjects that chose to take orlistat and 27.7% (SD 5.5%) in subjects not taking orlistat [between group difference -5.0% (95% confidence interval -9.2 to -0.7); P = 0.021].

CONCLUSIONS

The use of orlistat compared with placebo in a lifestyle modification programme does not appear to influence dietary intake. Subjects that chose to take orlistat after the end of the programme did not comply with dietary recommendations and this may hamper the effect of the drug.

Dietary Guidelines should reflect new understandings about adult protein needs

Dietary Guidelines for Americans provide nutrition advice aimed at promoting healthy dietary choices for life-long health and reducing risk of chronic diseases. With the advancing age of the population, the 2010 Dietary Guidelines confront increasing risks for age-related problems of obesity, osteoporosis, type 2 diabetes, Metabolic Syndrome, heart disease, and sarcopenia. New research demonstrates that the meal distribution and amount of protein are important in maintaining body composition, bone health and glucose homeostasis. This editorial reviews the benefits of dietary protein for adult health, addresses omissions in current nutrition guidelines, and offers concepts for improving the Dietary Guidelines.

Laboratory assessment of the food intake of children and adolescents with loss of control eating

BACKGROUND

Loss of control (LOC) eating in youth predicts excessive weight gain. However, few studies have measured the actual energy intake of children reporting LOC eating.

OBJECTIVE

The objective was to characterize the energy intake and macronutrient composition of "normal" and "binge" laboratory meals in nonoverweight and overweight boys and girls with LOC eating.

DESIGN

Children aged 8-17 y (n = 177) consumed 2 lunchtime meals ad libitum from a multi-item food array after being instructed to either binge eat (binge meal) or to eat normally (normal meal). Prior LOC eating was determined with a semistructured clinical interview.

RESULTS

Participants consumed more energy at the binge meal than at the normal meal (P = 0.001). Compared with youth with no LOC episodes (n = 127), those reporting LOC (n = 50) did not consume more energy at either meal. However, at both meals, youth with LOC consumed a greater percentage of calories from carbohydrates and a smaller percentage from protein than did those without LOC (P < 0.05). Children with LOC ate more snack and dessert-type foods and less meats and dairy (P < 0.05). LOC participants also reported greater increases in postmeal negative affect at both meals than did those without LOC (P < or = 0.05). Secondary analyses restricted to overweight and obese girls found that those with LOC consumed more energy at the binge meal (P = 0.025).

CONCLUSIONS

When presented with an array of foods, youth with LOC consumed more high-calorie snack and dessert-type foods than did those without LOC. Further research is required to determine whether habitual consumption of such foods may promote overweight. This trial was registered at clinicaltrials.gov as NCT00320177.

A moderate-protein diet produces sustained weight loss and long-term changes in body composition and blood lipids in obese adults

Diets with increased protein and reduced carbohydrates (PRO) are effective for weight loss, but the long-term effect on maintenance is unknown. This study compared changes in body weight and composition and blood lipids after short-term weight loss (4 mo) followed by weight maintenance (8 mo) using moderate PRO or conventional high-carbohydrate (CHO) diets. Participants (age = 45.4 +/- 1.2 y; BMI = 32.6 +/- 0.8 kg/m(2); n = 130) were randomized to 2 energy-restricted diets (-500 kcal/d or -2093 kJ/d): PRO with 1.6 g x kg(-1) x d(-1) protein and <170 g/d carbohydrates or CHO with 0.8 g x kg(-1) x d(-1) protein, >220 g/d carbohydrates. At 4 mo, the PRO group had lost 22% more fat mass (FM) (-5.6 +/- 0.4 kg) than the CHO group (-4.6 +/- 0.3 kg) but weight loss did not differ between groups (-8.2 +/- 0.5 kg vs. -7.0 +/- 0.5 kg; P = 0.10). At 12 mo, the PRO group had more participants complete the study (64 vs. 45%, P < 0.05) with greater improvement in body composition; however, weight loss did not differ between groups (-10.4 +/- 1.2 kg vs. -8.4 +/- 0.9 kg; P = 0.18). Using a compliance criterion of participants attaining >10% weight loss, the PRO group had more participants (31 vs. 21%) lose more weight (-16.5 +/- 1.5 vs. -12.3 +/- 0.9 kg; P < 0.01) and FM (-11.7 +/- 1.0 vs. -7.9 +/- 0.7 kg; P < 0.01) than the CHO group. The CHO diet reduced serum cholesterol and LDL cholesterol compared with PRO (P < 0.01) at 4 mo, but the effect did not remain at 12 mo. PRO had sustained favorable effects on serum triacylglycerol (TAG), HDL cholesterol (HDL-C), and TAG:HDL-C compared with CHO at 4 and 12 mo (P < 0.01). The PRO diet was more effective for FM loss and body composition improvement during initial weight loss and long-term maintenance and produced sustained reductions in TAG and increases in HDL-C compared with the CHO diet.

The dietary treatment of obesity

Dietary modulation is an essential part of weight loss and maintaining its reduction. Although simple in behavioral terms (eat less, exercise more), the tremendous difficulty of weight loss and maintenance has inspired many different diet regimens, in search of an easier, more efficient way to lose weight. Contemporary issues in this matter are the composition of diets (low fat versus low carbohydrate), the choice of carbohydrate (the glycemic index), and the role of calcium and dairy products. This article discusses the scientific evidence of the various dietary manipulations for weight loss and the challenges of maintaining a reduced obese state.

Endothelial dysfunction and diabetes: roles of hyperglycemia, impaired insulin signaling and obesity

Endothelial dysfunction comprises a number of functional alterations in the vascular endothelium that are associated with diabetes and cardiovascular disease, including changes in vasoregulation, enhanced generation of reactive oxygen intermediates, inflammatory activation, and altered barrier function. Hyperglycemia is a characteristic feature of type 1 and type 2 diabetes and plays a pivotal role in diabetes-associated microvascular complications. Although hyperglycemia also contributes to the occurrence and progression of macrovascular disease (the major cause of death in type 2 diabetes), other factors such as dyslipidemia, hyperinsulinemia, and adipose-tissue-derived factors play a more dominant role. A mutual interaction between these factors and endothelial dysfunction occurs during the progression of the disease. We pay special attention to the possible involvement of endoplasmic reticulum stress (ER stress) and the role of obesity and adipose-derived adipokines as contributors to endothelial dysfunction in type 2 diabetes. The close interaction of adipocytes of perivascular adipose tissue with arteries and arterioles facilitates the exposure of their endothelial cells to adipokines, particularly if inflammation activates the adipose tissue and thus affects vasoregulation and capillary recruitment in skeletal muscle. Hence, an initial dysfunction of endothelial cells underlies metabolic and vascular alterations that contribute to the development of type 2 diabetes.

Reduced postprandial energy expenditure and increased exogenous fat oxidation in young woman after ingestion of test meals with a low protein content

BACKGROUND

Macronutrient composition of diets can influence energy balance in humans. We tested the hypothesis whether low protein content in single meals may induce lower values of energy expenditure (EE) and fat oxidation (FO) as compared to adequate protein content.

METHODS

Indirect calorimetry was combined with a breath test using naturally 13C-enriched corn oil to differentiate between postprandial exogenous and endogenous FO. Young women ingested single meals containing either 3.9% (low protein, LP) or 11.4% (adequate protein, AP) of total energy (~3100 kJ) as protein.

RESULTS

Postprandial EE was 160 kJ/6 h lower (p < 0.01) after LP meals and diet induced thermogenesis (DIT) increased less (p < 0.001) as compared to AP meals. Total postprandial FO was not significantly different between meals (~17 g/6 h). However, exogenous postprandial FO was significantly (p < 0.01) higher (4.28 +/- 1.57 g/6 h) after exposure to LP meals as compared to AP meals (1.87 +/- 1.00 g/6 h). Less than 10% of ingested fat (50 g) was oxidized in the postprandial phase. The overall postprandial fat balance was approximately + 33 g.

CONCLUSION

Breath tests using naturally 13C-labeled corn oil mirror exogenous FO. Low protein meals resulted in reduced postprandial EE and increased exogenous FO as compared to adequate protein meals without differences in total FO.

An isoenergetic high-protein, moderate-fat diet does not compromise strength and fatigue during resistance exercise in women

Resistance exercise is recommended to individuals following high-protein diets in order to augment changes in body composition. However, alterations in macronutrient composition may compromise physical performance. The present study investigated the effects of an isoenergetic high-protein diet on upper and lower limb strength and fatigue during high-intensity resistance exercise. Ten recreationally active women, aged 25–40 years, followed a control diet (55, 15 and 30 % of energy from carbohydrate, protein and fat, respectively) and a high-protein diet (respective values, 30, 40 and 30) for 7 d each in a random counterbalanced design. Each participant underwent strength testing of upper limb (isometric handgrip strength and endurance) and lower limb (four sets of sixteen maximal knee flexions and extensions on an isokinetic dynamometer) before and after applying each diet. Body weight, body fat and RER were significantly reduced following the high-protein diet (P < 0·05). No differences were found between diets in any of the strength performance parameters (handgrip strength, handgrip endurance, peak torque, total work and fatigue) or the responses of heart rate, systolic and diastolic arterial pressure, blood lactate and blood glucose to exercise. Women on a short-term isoenergetic high-protein, moderate-fat diet maintained muscular strength and endurance of upper and lower limbs during high-intensity resistance exercise without experiencing fatigue earlier compared with a control diet.

Minimal nutrition intervention with high-protein/low-carbohydrate and low-fat, nutrient-dense food supplement improves body composition and exercise benefits in overweight adults: A randomized controlled trial

Background

Exercise and high-protein/reduced-carbohydrate and -fat diets have each been shown separately, or in combination with an energy-restricted diet to improve body composition and health in sedentary, overweight (BMI > 25) adults. The current study, instead, examined the physiological response to 10 weeks of combined aerobic and resistance exercise (EX) versus exercise + minimal nutrition intervention designed to alter the macronutrient profile, in the absence of energy restriction, using a commercially available high-protein/low-carbohydrate and low-fat, nutrient-dense food supplement (EXFS); versus control (CON).

Methods

Thirty-eight previously sedentary, overweight subjects (female = 19; male = 19) were randomly assigned to either CON (n = 10), EX (n = 14) or EXFS (n = 14). EX and EXFS participated in supervised resistance and endurance training (2× and 3×/wk, respectively); EXFS consumed 1 shake/d (weeks 1 and 2) and 2 shakes/d (weeks 3–10).

Results

EXFS significantly decreased total energy, carbohydrate and fat intake (-14.4%, -27.2% and -26.7%, respectively; p < 0.017), and increased protein and fiber intake (+52.1% and +21.2%, respectively; p < 0.017). EX and EXFS significantly decreased fat mass (-4.6% and -9.3%, respectively; p < 0.017), with a greater (p < 0.05) decrease in EXFS than EX and CON. Muscle mass increase only reached significance in EXFS (+2.3%; p < 0.017), which was greater (p < 0.05) than CON but not EX (+1.1%). Relative VO₂max improved in both exercise groups (EX = +5.0% and EXFS = +7.9%; p < 0.017); however, only EXFS significantly improved absolute VO₂max (+6.2%; p = 0.001). Time-to-exhaustion during treadmill testing increased in EX (+9.8%) but was significantly less (p < 0.05) than in EXFS (+21.2%). Total cholesterol and LDL decreased only in the EXFS (-12.0% and -13.3%, respectively; p < 0.017). Total cholesterol-to-HDL ratio, however, decreased significantly (p < 0.017) in both exercise groups.

Conclusion

Absent energy restriction or other dietary controls, provision of a high-protein/low-carbohydrate and -fat, nutrient-dense food supplement significantly, 1) modified ad libitum macronutrient and energy intake (behavior effect), 2) improved physiological adaptations to exercise (metabolic advantage), and 3) reduced the variability of individual responses for fat mass, muscle mass and time-to-exhaustion – all three variables improving in 100% of EXFS subjects.

Adequate nutrition followed by revisional bariatric surgery to optimize homeostatic eating control

Terms as treatment failure or ineffective treatment after bariatric surgery are not clearly defined and difficult to handle. About one third of all persons who were formerly treated with a Lapband have either mechanical problems or do not lose enough weight. The current review argues in favor of adequate nutrition to suppress hunger and optimize satiety together with effective but least malabsorptive revisional surgery. This approach aims at switching the gut-brain axis, thereby facilitating homeostatic eating control.

Blood ketones are directly related to fatigue and perceived effort during exercise in overweight adults adhering to low-carbohydrate diets for weight loss: a pilot study

Ketogenic diets have been associated with reductions in free-living physical activity, a response that can be counterproductive in individuals trying to lose weight. To explore whether popular low-carbohydrate diets might impact the desire to exercise by raising blood ketone concentrations, fatigue and perceived effort during exercise were compared in untrained, overweight adults adhering to a ketogenic low-carbohydrate diet or to a control diet low in carbohydrate, but not ketogenic (5%, 65%, and 30% or 40%, 30%, and 30% of energy from carbohydrate, fat, and protein, respectively). In this prospective, randomized, 2-week pilot study, all meals and snacks were provided to subjects, and energy intake was strictly controlled to provide approximately 70% of that needed for weight maintenance. At baseline and at the end of week 2, exercise testing was conducted in fasting participants. Weight loss and the reductions in fat mass did not differ by group during the trial. At week 2, blood beta-hydroxybutyrate concentrations were 3.6-fold greater for the ketogenic vs nonketogenic group (P=0.018) and correlated significantly with perceived exercise effort (r2=0.22, P=0.049). Blood beta-hydroxybutyrate was also significantly correlated to feelings of "fatigue" (r=0.458, P=0.049) and to "total mood disturbance" (r=0.551, P=0.015) while exercising. These pilot data indicate that ketogenic, low-carbohydrate diets enhance fatigability and can reduce the desire to exercise in free-living individuals.

Diet Composition and Risk of Overweight and Obesity in Women Living in the Southwestern United States

OBJECTIVE

It is unknown whether dietary patterns or macronutrient composition contribute to the observed differences in rates of overweight and obesity among Hispanic and non-Hispanic white women in the United States. We assessed the association of dietary patterns and macronutrient composition with overweight and obesity in Hispanic and non-Hispanic white women.

DESIGN

Cross-sectional analysis of dietary data from a case-control study of breast cancer.

PARTICIPANTS

Population-based control participants (871 Hispanic and 1,599 non-Hispanic white women) from the southwestern United States who completed the diet and other components of the interview and whose anthropometric measurements were available.

MAIN OUTCOME MEASURES

Body mass index (BMI; calculated as kg/m(2)), weight status (overweight, BMI 25 to 29.9; obese, BMI>30).

STATISTICAL ANALYSES PERFORMED

Dietary patterns were defined using factor analysis. Associations of dietary patterns and macronutrient composition with overweight and obesity as compared with normal weight were assessed with logistic regression.

RESULTS

Hispanic women reported consuming more energy, a greater proportion of energy from fat and vegetable protein, less alcohol, and less energy from animal protein compared with non-Hispanic white women. Western and dieter patterns were associated with higher prevalence of overweight and obesity; the Prudent dietary pattern was associated with a 29% lower prevalence of overweight and a halving of the prevalence of obesity similarly in Hispanic and non-Hispanic white women. Higher proportions of energy from protein (odds ratio [OR] 1.81, 95% confidence interval [CI] 1.28 to 2.56) and animal protein (OR 2.10 95% CI 1.47 to 2.98) were associated with a greater risk of overweight; greater proportions of energy from fat (OR 2.28, 95% CI 1.27 to 4.08), protein (3.55 95% CI 2.38 to 5.29), or animal protein (3.44 95% CI 2.31 to 5.14) were associated with higher risk of obesity among non-Hispanic white women only.

CONCLUSIONS

A Western dietary pattern was associated with greater risk and a Prudent diet with reduced risk of overweight and obesity. To reduce risk of overweight and obesity, Hispanic women should maintain healthful aspects of a native Hispanic diet, and non-Hispanic white women should replace animal protein with vegetable protein.