Dynamics of Change in Total and Regional Body Composition After Gastric Bypass in Obese Patients

Little is known on patterns of change over time in body composition, especially lean body mass (LBM), during massive weight loss after Roux‐en‐Y gastric bypass (RYGB) in obese patients. We performed sequential measurements of total and regional body composition in patients after RYGB, and we compared a subsample of patients after surgery to a nonsurgical control group of similar age and body fatness. We used dual‐energy X‐ray absorptiometry (DXA) before and at 3, 6, and 12 months after RYGB in 42 obese women (before surgery: age 39.5 ± 11.6 years; BMI 44.6 ± 6.1 kg/m²; mean ± s.d.) and in 48 control obese women referred for nonsurgical weight management, before weight loss. During 1‐year follow‐up after RYGB, there was a continuous decrease in body weight (?36.0 ± 12.5 kg at 1 year), total fat mass (FM) (?26.0 ± 9.1 kg), as well as in trunk and appendicular FM. In contrast, the decrease in total LBM (?9.8 ± 4.8 kg at 1 year), as well as in trunk and appendicular LBM, plateaued after 3–6 months. Rates of loss in weight, FM, and LBM were highest during the first 3‐month period after RYGB (6.4 ± 1.8, 4.1 ± 1.7, and 2.3 ± 1.2 kg/month, respectively), then decreased continuously for FM but plateaued for LBM. There was no evidence of a decrease in total, trunk, or appendicular LBM in weight‐reduced subjects compared to the control group. In conclusion, follow‐up of these obese women revealed a differential pattern of change in FM and LBM after RYGB. Despite an important loss in LBM, especially during the 3–6 months of initial period, LBM appears to be spared thereafter.     

Efficacy of α‐Lactalbumin and Milk Protein on Weight Loss and Body Composition During Energy Restriction

Our objective was to examine whether elevated α‐lactalbumin (αlac) protein intake compared to elevated supra sustained milk protein (SSP) and sustained milk protein (SP) intake results into a difference in body weight and body composition over a 6‐month energy‐restriction intervention. Body weight, body composition, resting energy expenditure (REE), satiety and blood‐ and urine‐parameters of 87 subjects (BMI 31 ± 5 kg/m² and fat percentage 40 ± 8%) were assessed before and after daily energy intakes of 100, 33, and 67% for 1, 1, and 2 months respectively (periods 1, 2, and 3), with protein intake from meal replacements and 2 months of 67% with ad libitum protein intake additional to the meal replacements (period 4). The diets resulted in 0.8 ± 0.3 g/kg body mass (BM) for SP and significant higher protein intake (24‐h nitrogen) of 1.2 ± 0.3 and 1.0 ± 0.3 g/kgBM for SSP and αlac (P < 0.05). Body weight and fat percentage was decreased in all groups after 6 months (SP ?7 ± 5 kg and ?5 ± 3%; SSP ?6 ± 3 kg and ?5 ± 3%; αlac ?6 ± 4 kg and ?4 ± 4%, P < 0.001; there was no significant group by time difference). Furthermore, sparing of fat‐free mass (FFM) and preservation of REE in function of FFM during weight loss was not significantly different between the αlac‐group and the SSP‐ and SP‐groups. In conclusion, the efficacy of αlac in reduction of body weight and fat mass (FM), and preservation of FFM does not differ from the efficacy of similar daily intakes of milk protein during 6 months of energy restriction.     

Brown Adipose Tissue,Whole‐Body Energy Expenditure,and Thermogenesis in Healthy Adult Men

Brown adipose tissue (BAT) can be identified by ¹⁸F‐fluorodeoxyglucose (FDG)‐positron emission tomography (PET) in adult humans. Thirteen healthy male volunteers aged 20–28 years underwent FDG‐PET after 2‐h cold exposure at 19 °C with light‐clothing and intermittently putting their legs on an ice block. When exposed to cold, 6 out of the 13 subjects showed marked FDG uptake into adipose tissue of the supraclavicular and paraspinal regions (BAT‐positive group), whereas the remaining seven showed no detectable uptake (BAT‐negative group). The BMI and body fat content were similar in the two groups. Under warm conditions at 27 °C, the energy expenditure of the BAT‐positive group estimated by indirect calorimetry was 1,446 ± 97 kcal/day, being comparable with that of the BAT‐negative group (1,434 ± 246 kcal/day). After cold exposure, the energy expenditure increased markedly by 410 ± 293 (P < 0.05) and slightly by 42 ± 114 kcal/day (P = 0.37) in the BAT‐positive and ‐negative groups, respectively. A positive correlation (P < 0.05) was found between the cold‐induced rise in energy expenditure and the BAT activity quantified from FDG uptake. After cold exposure, the skin temperature in the supraclavicular region close to BAT deposits dropped by 0.14 °C in the BAT‐positive group, whereas it dropped more markedly (P < 0.01) by 0.60 °C in the BAT‐negative group. The skin temperature drop in other regions apart from BAT deposits was similar in the two groups. These results suggest that BAT is involved in cold‐induced increases in whole‐body energy expenditure, and, thereby, the control of body temperature and adiposity in adult humans.     

Medium‐Chain Triglycerides Increase Energy Expenditure and Decrease Adiposity in Overweight Men

Objective: The objectives of this study were to compare the effects of diets rich in medium‐chain triglycerides (MCTs) or long‐chain triglycerides (LCTs) on body composition, energy expenditure, substrate oxidation, subjective appetite, and ad libitum energy intake in overweight men. Research Methods and Procedures: Twenty‐four healthy, overweight men with body mass indexes between 25 and 31 kg/m² consumed diets rich in MCT or LCT for 28 days each in a crossover randomized controlled trial. At baseline and after 4 weeks of each dietary intervention, energy expenditure was measured using indirect calorimetry, and body composition was analyzed using magnetic resonance imaging. Results: Upper body adipose tissue (AT) decreased to a greater extent (p < 0.05) with functional oil (FctO) compared with olive oil (OL) consumption (?0.67 ± 0.26 kg and ?0.02 ± 0.19 kg, respectively). There was a trend toward greater loss of whole‐body subcutaneous AT volume (p = 0.087) with FctO compared with OL consumption. Average energy expenditure was 0.04 ± 0.02 kcal/min greater (p < 0.05) on day 2 and 0.03 ± 0.02 kcal/min (not significant) on day 28 with FctO compared with OL consumption. Similarly, average fat oxidation was greater (p = 0.052) with FctO compared with OL intake on day 2 but not day 28. Discussion: Consumption of a diet rich in MCTs results in greater loss of AT compared with LCTs, perhaps due to increased energy expenditure and fat oxidation observed with MCT intake. Thus, MCTs may be considered as agents that aid in the prevention of obesity or potentially stimulate weight loss.     

A low‐glycemic diet lifestyle intervention improves fat utilization during exercise in older obese humans

Objective: To determine the influence of dietary glycemic index on exercise training‐induced adaptations in substrate oxidation in obesity. Design and Methods: Twenty older, obese individuals undertook 3 months of fully supervised aerobic exercise and were randomized to low‐ (LoGIX) or high‐glycemic (HiGIX) diets. Changes in indirect calorimetry (VO₂; VCO₂) were assessed at rest, during a hyperinsulinemic‐euglycemic clamp, and during submaximal exercise (walking: 65% VO₂max, 200 kcal energy expenditure). Intramyocellular lipid (IMCL) was measured by ¹H‐magnetic resonance spectroscopy. Results: Weight loss (?8.6 ± 1.1%) and improvements (P < 0.05) in VO₂max, glycemic control, fasting lipemia, and metabolic flexibility were similar for both LoGIX and HiGIX groups. During submaximal exercise, energy expenditure was higher following the intervention (P < 0.01) in both groups. Respiratory exchange ratio during exercise was unchanged in the LoGIX group but increased in the HiGIX group (P < 0.05). However, fat oxidation during exercise expressed in relation to changes in body weight was increased in the LoGIX group (+10.6 ± 3.6%; P < 0.05). Fasting IMCL was unchanged, however, extramyocellular lipid was reduced (P < 0.05) after LoGIX. Conclusions: A LoGIX/exercise weight‐loss intervention increased fat utilization during exercise independent of changes in energy expenditure. This highlights the potential therapeutic value of low‐glycemic foods for reversing metabolic defects in obesity.     

The comparison of a technology-based system and an in-person behavioral weight loss intervention

The purpose of this study was to compare a technology‐based system, an in‐person behavioral weight loss intervention, and a combination of both over a 6‐month period in overweight adults. Fifty‐one subjects (age: 44.2 ± 8.7 years, BMI: 33.7 ± 3.6 kg/m²) participated in a 6‐month behavioral weight loss program and were randomized to one of three groups: standard behavioral weight loss (SBWL), SBWL plus technology‐based system (SBWL+TECH), or technology‐based system only (TECH). All groups reduced caloric intake and progressively increased moderate intensity physical activity. SBWL and SBWL+TECH attended weekly meetings. SBWL+TECH also received a TECH that included an energy monitoring armband and website to monitor energy intake and expenditure. TECH used the technology system and received monthly telephone calls. Body weight and physical activity were assessed at 0 and 6 months. Retention at 6 months was significantly different (P = 0.005) between groups (SBWL: 53%, SBWL+TECH: 100%, and TECH: 77%). Intent‐to‐treat (ITT) analysis revealed significant weight losses at 6 months in SBWL+TECH (?8.8 ± 5.0 kg, ?8.7 ± 4.7%), SBWL (?3.7 ± 5.7 kg, ?4.1 ± 6.3%), and TECH (?5.8 ± 6.6 kg, ?6.3 ± 7.1%) (P < 0.001). Self‐report physical activity increased significantly in SBWL (473.9 ± 800.7 kcal/week), SBWL+TECH (713.9 ± 1,278.8 kcal/week), and TECH (1,066.2 ± 1,371 kcal/week) (P < 0.001), with no differences between groups (P = 0.25). The TECH used in conjunction with monthly telephone calls, produced similar, if not greater weight losses and changes in physical activity than the standard in‐person behavioral program at 6 months. The use of this technology may provide an effective short‐term clinical alternative to standard in‐person behavioral weight loss interventions, with the longer term effects warranting investigation.     

Greater Than Predicted Decrease in Resting Energy Expenditure and Weight Loss: Results From a Systematic Review

Changes in resting energy expenditure (EE) during weight loss are said to be greater than what can be expected from changes of body mass, i.e., fat mass (FM) and fat‐free mass (FFM) but controversy persists. The primary focus of this study was to investigate whether there is a greater than predicted decrease in resting EE during weight loss in a large sample size through a systematic review. The study data were weighted and a partial residual plot followed by a multiple regression analysis was performed to determine whether FM and FFM can predict the changes of resting EE after weight loss. Another subgroup of studies from which all necessary information was available was analyzed and compared against the Harris—Benedict (HB) prediction equation to determine whether the changes in resting EE were greater than what was expected. Subjects lost 9.4 ± 5.5 kg (P < 0.01) with a mean resting EE decline of 126.4 ± 78.1 kcal/day (P < 0.01). Changes in FM and FFM explained 76.5% and 79.3% of the variance seen in absolute resting EE at baseline and post‐weight loss, respectively (P < 0.01). Analysis of the 1,450 subject subgroup indicated an ～29.1% greater than predicted decrease in resting EE when compared to the HB prediction equation (P < 0.01). This analysis does not support the notion of a greater than predicted decrease in resting EE after weight loss.     

A Weight Reduction Program Preserves Fat‐Free Mass but Not Metabolic Rate in Obese Adolescents

Objective: To determine the effects of a multidisciplinary weight reduction program on body composition and energy expenditure (EE) in severely obese adolescents. Research Methods and Procedures: Twenty‐six severely obese adolescents, 12 to 16 years old [mean BMI: 33.9 kg/m²; 41.5% fat mass (FM)] followed a 9‐month weight reduction program including moderate energy restriction and progressive endurance and resistance training. Body composition was assessed by DXA, basal metabolic rate by indirect calorimetry, and EE by whole‐body indirect calorimetry with the same activity program over 36‐hour periods before starting and 9 months after the weight reduction period. Results: Adolescents gained (least‐square mean ± SE) 2.9 ± 0.2 cm in height, lost 16.9 ± 1.3 kg body weight (BW), 15.2 ± 0.9 kg FM, and 1.8 ± 0.5 kg fat‐free mass (FFM) (p < 0.001). Basal metabolic rate, sleeping, sedentary, and daily EE were 8% to 14% lower 9 months after starting (p < 0.001) and still 6% to 12% lower after adjustment for FFM (p < 0.05). Energy cost of walking decreased by 22% (p < 0.001). The reduction in heart rate during sleep and sedentary activities (?10 to ?13 beats/min), and walking (?20 to ?25 beats/min) (p < 0.001) resulted from both the decrease in BW and physical training. Discussion: A weight reduction program combining moderate energy restriction and physical training in severely obese adolescents resulted in great BW and FM losses and improvement of cardiovascular fitness but did not prevent the decline in EE even after adjustment for FFM.     

Resistance Training Preserves Fat‐free Mass Without Impacting Changes in Protein Metabolism After Weight Loss in Older Women

This study assessed the effects of resistance training (RT) on energy restriction–induced changes in body composition, protein metabolism, and the fractional synthesis rate of mixed muscle proteins (FSRm) in postmenopausal, overweight women. Sixteen women (age 68 ± 1 years, BMI 29 ± 1 kg/m², mean ± s.e.m.) completed a 16‐week controlled diet study. Each woman consumed 1.0 g protein/kg/day. At baseline (weeks B1–B3) and poststudy (weeks RT12–RT13), energy intake matched each subject's need and during weeks RT1–RT11 was hypoenergetic by 2,092 kJ/day (500 kcal/day). From weeks RT1 to RT13, eight women performed RT 3 day/week (RT group) and eight women remained sedentary (SED group). RT did not influence the energy restriction–induced decrease in body mass (SED ?5.8 ± 0.6 kg; RT ?5.0 ± 0.2 kg) and fat mass (SED ?4.1 ± 0.9 kg; RT ?4.7 ± 0.5 kg). Fat free mass (FFM) and total body water decreased in SED (?1.6 ± 0.4 and ?2.1 ± 0.5 kg) and were unchanged in RT (?0.3 ± 0.4 and ?0.4 ± 0.7 kg) (group‐by‐time, P ≤ 0.05 and P = 0.07, respectively). Protein–mineral mass did not change in either group (SED 0.4 ± 0.2 kg; RT 0.1 ± 0.4 kg). Nitrogen balance, positive at baseline (2.2 ± 0.3 g N/day), was unchanged poststudy. After body mass loss, postabsorptive (PA) and postprandial (PP) leucine turnover, synthesis, and breakdown decreased. Leucine oxidation and balance were not changed. PA and total (PA + PP) FSRm in the vastus lateralis were higher after weight loss. RT did not influence these protein metabolism responses. In summary, RT helps older women preserve FFM during body mass loss. The comparable whole‐body nitrogen retentions, leucine kinetics, and FSRm between groups are consistent with the lack of differential protein–mineral mass change.     

Visceral obesity is a negative predictor of remission of diabetes 1 year after bariatric surgery

Our aim was to identify preoperative anthropometric and clinical parameters that predict the remission of diabetes after Roux‐en‐Y gastric bypass (RYGB). Fifty severely obese Korean patients with type 2 diabetes underwent RYGB. Visceral and abdominal subcutaneous fat area (SFA) was assessed using computed tomography before and 6 and 12 months after RYGB. Remission was defined as a glycated hemoglobin (A_1C) level <6.5% and a fasting glucose concentration <126 mg/dl for 1 year or more without the use of medication. The visceral‐to‐SFA ratio decreased from 0.60 ± 0.30 to 0.53 ± 0.29 (P = 0.001) after 6 months and decreased further to 0.42 ± 0.24 (P < 0.001) after 12 months. Thirty‐four of the 50 patients (68%) had remission of diabetes (remission group). Compared with patients in the nonremission group, patients in the remission group had a shorter duration of diabetes and lower preoperative A_1C level, and were less likely to use insulin preoperatively. Preoperative BMI did not differ in two groups. However, the preoperative visceral‐to‐SFA ratio was greater in the nonremission group compared with the remission group (0.79 ± 0.29 vs. 0.53 ± 0.26, P = 0.003). Finally, the preoperative visceral‐to‐SFA ratio was an independent predictor of the remission of diabetes after RYGB in multiple stepwise logistic regression analysis. In conclusion, our data suggest that visceral adiposity negatively influence the likelihood of the patient experiencing the remission of diabetes after RYGB.     

Physical Activity Levels Are Low in Free‐Living Adults with Chronic Paraplegia

Objectives: To compare physical activity levels (PALs) of free‐living adults with chronic paraplegia with World Health Organization recommendations and to compare energy expenditure between persons with complete vs. incomplete paraplegia. Research Methods and Procedures: Twenty‐seven euthyroid adults (17 men and 10 women) with paraplegia (12.5 ± 9.5 years since onset; 17 with complete lesions and 10 with incomplete lesions) participated in this cross‐sectional study. Resting metabolic rate was measured by indirect calorimetry and total daily energy expenditure (TDEE) by heart rate monitoring. PAL was calculated as TDEE/resting metabolic rate. Total body water was measured by deuterium dilution and fat‐free mass (FFM) and fat mass (FM) by calculation (FFM = total body water/0.732; FM = weight ? FFM). Obesity was defined using the following percentage FM cutoffs: men 18 to 40 years >22% and 41 to 60 years >25%; and women 18 to 40 years >35% and 41 to 60 years >38%. Results: Nineteen subjects (70.4%; 13 men and six women) were obese. Fifteen subjects (56%) engaged in structured physical activity 1.46 ± 0.85 times during the observation period for a mean of 49.4 ± 31.0 minutes per session. Despite this, mean PAL of the group was 1.56 ± 0.34, indicative of limited physical activity. TDEE was 24.6% lower in subjects with complete paraplegia (2072 ± 505 vs. 2582 ± 852 kcal/d, p = 0.0372). Discussion: PAL of the group was low, indicating that persons with paraplegia need to engage in increased frequency, intensity, and/or duration of structured physical activity to achieve a PAL ≥1.75 and, thereby, to offset sedentary activities of daily living.     

Endothelial function and weight loss: Comparison of low‐carbohydrate and low‐fat diets

Objective: The effect of weight loss on obesity‐associated endothelial dysfunction is not clear because of conflicting data, demonstrating both improvement and no change in endothelial function after weight loss in obese subjects. A 2‐year prospective study (n = 121) was conducted to examine: (1) the effect of obesity and weight loss (either a low‐carbohydrate or and low‐fat diet) on flow mediated vasodilatation (FMD), a measure of endothelial function. Design and Methods: Participants reduced body weight by 7.1% ± 4.4%, 8.7% ± 6.8%, 7.1% ± 7.8%, and 4.1% ± 7.7% at 3, 6, 12, and 24 months, respectively with no significant differences between the low‐fat and low‐carbohydrate groups. Results: Endothelial function was inversely correlated with waist circumference, triglyceride level, and directly correlated with leptin in obese persons prior to weight loss. These weight losses did not confer any improvements in FMD. There were no differences between the low‐fat and low‐carbohydrate diets in FMD at any time point. At 6 months (r = 0.26, P = 0.04) and 1 year (r =0.28, P = 0.03), there were positive correlations between change in FMD and change in leptin but not at 2 years. Conclusion: There was no significant improvement in endothelial function after 7.1% ± 7.8% weight loss at 1 year and 4.1% ± 7.7% at 2 years, achieved by either a low carbohydrate or a low fat diet.     

Changes of Body Weight and Plasma Ghrelin Levels after Gastric Banding and Gastric Bypass

Objective: Ghrelin is an enteric peptide with strong orexigenic and adipogenic effects. Plasma ghrelin levels are decreased in obese subjects but increase after weight loss; this increase is not observed after Roux‐en‐Y gastric bypass (RYGB). Prospective and comparative data after adjustable silicone gastric banding (ASGB) have not been reported previously. Research Methods and Procedures: Overnight fasting plasma ghrelin concentration was measured in morbidly obese subjects at baseline and 3, 6, 12, and 24 months after ASGB (n = 8) or RYGB (n = 5) and in nonoperated controls (n = 7). Results: After RYGB, body weight (BW) decreased by 29.5 ± 5.5 kg (mean ± SE, p < 0.001), whereas plasma ghrelin failed to increase significantly (+167 ± 119 pg/mL, not significant). In contrast, after ASGB, BW decreased less (by 22.8 ± 5.9 kg; p < 0.001), and plasma ghrelin significantly increased by 377 ± 201 pg/mL (p = 0.025). Neither BW nor plasma ghrelin changed in nonoperated controls. Plasma leptin decreased in both operated groups (similarly p < 0.05) but not in nonoperated controls. Plasma growth hormone and insulin‐like growth factor 1 were not correlated with changes in plasma ghrelin concentrations. Discussion: Plasma ghrelin levels failed to increase during substantial weight loss after RYGB, but did increase in response to lesser weight loss after ASGB. These findings suggest that the plasma ghrelin response after weight loss is impaired after exclusion of major parts of the stomach and the duodenum (RYGB), and the smaller long‐term weight loss after ASGB compared with RYGB may be due, at least in part, to an absent increase in plasma ghrelin after RYGB.     

Gastric bypass surgery reduces plasma ceramide subspecies and improves insulin sensitivity in severely obese patients

Bariatric surgery is associated with near immediate remission of type 2 diabetes and hyperlipidemia. The mechanisms underlying restoration of normal glucose tolerance postoperatively are poorly understood. Herein, we examined the effect of Roux‐en‐Y gastric bypass surgery (RYGB) on weight loss, insulin sensitivity, plasma ceramides, proinflammatory markers, and cardiovascular risk factors before and at 3 and 6 months after surgery. Thirteen patients (10 female; age 48.5 ± 2.7 years; BMI, 47.4 ± 1.5 kg/m²) were included in the study, all of whom had undergone laparoscopic RYGB surgery. Insulin sensitivity, inflammatory mediators and fasting lipid profiles were measured at baseline, 3 and 6 months postoperatively, using enzymatic analysis. Plasma ceramide subspecies (C14:0, C16:0, C18:0, C18:1, C20:0, C24:0, and C24:1) were quantified using electrospray ionization tandem mass spectrometry after separation with HPLC. At 3 months postsurgery, body weight was reduced by 25%, fasting total cholesterol, triglycerides, low‐density lipoproteins, and free fatty acids were decreased, and insulin sensitivity was increased compared to presurgery values. These changes were all sustained at 6 months. In addition, total plasma ceramide levels decreased significantly postoperatively (9.3 ± 0.5 nmol/ml at baseline vs. 7.6 ± 0.4 at 3 months, and 7.3 ± 0.3 at 6 months, P < 0.05). At 6 months, the improvement in insulin sensitivity correlated with the change in total ceramide levels (r = ?0.68, P = 0.02), and with plasma tumor necrosis factor‐α (TNF‐α) (r = ?0.62, P = 0.04). We conclude that there is a potential role for ceramide lipids as mediators of the proinflammatory state and improved insulin sensitivity after gastric bypass surgery.     

Resting Energy Expenditure Changes With Weight Loss: Racial Differences

It is controversial whether weight loss reduces resting energy expenditure (REE) to a different magnitude in black and white women. This aim of this study was to determine whether changes in REE with weight loss were different between black and white postmenopausal women, and whether changes in body composition (including regional lean and fat mass) were associated with REE changes within each race. Black (n = 26) and white (n = 65) women (age = 58.2 ± 5.4 years, 25 < BMI < 40 kg/m²) completed a 20‐week weight‐loss intervention. Body weight, lean and fat mass (total body, limb, and trunk) via dual‐energy X‐ray absorptiometry, and REE via indirect calorimetry were measured before and after the intervention. We found that baseline REE positively correlated with body weight, lean and fat mass (total, limb, and trunk) in white women only (P < 0.05 for all). The intervention decreased absolute REE in both races similarly (1,279 ± 162 to 1,204 ± 169 kcal/day in blacks; 1,315 ± 200 to 1,209 ± 185 kcal/day in whites). REE remained decreased after adjusting for changes in total or limb lean mass in black (1,302–1,182 kcal/day, P = 0.043; 1,298–1,144 kcal/day, P = 0.006, respectively), but not in white, women. Changes in REE correlated with changes in body weight (partial r = 0.277) and fat mass (partial r = 0.295, 0.275, and 0.254 for total, limb, and trunk, respectively; P < 0.05) independent of baseline REE in white women. Therefore, with weight loss, REE decreased in proportion to the amount of fat and lean mass lost in white, but not black, women.     

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.     

Role of β2‐Adrenergic Receptor Polymorphisms on Body Weight and Body Composition Response to Energy Restriction in Obese Women: Preliminary Results

We investigated the role of common β2‐adrenergic receptor (ADRB2) rs1042714 (Gln27Glu) and rs1042713 (Arg16Gly) polymorphisms on body weight and body composition response to 12‐week energy‐restricted diet in women. The study comprised 78 Spanish obese (BMI: 34.0 ± 2.8 kg/m²) women (age: 36.7 ± 7 years). We measured (before and after the dietary intervention) weight and height, and BMI calculated. Moreover, body fat mass and lean mass (LM) were measured by dual energy X‐ray absorptiometry. We observed an interaction effect between the Gln27Glu polymorphism and diet‐induced changes on body weight (P = 0.006), BMI (P = 0.004), and LM (P = 0.001). Women carrying the Glu allele had a greater reduction in body weight than non‐Glu allele carriers (9.5 ± 2.9 vs. 7.0 ± 3.5%, respectively, P = 0.002). Moreover, women with the Glu allele lost more LM than the Gln27Gln group (5.9 ± 2.7 vs. 4.0 ± 2.7%, respectively, P = 0.001). We did not find any significant interaction effect between the Arg16Gly polymorphism and diet‐induced changes on the outcome variables (all P > 0.1). The results suggest that the ADRB2 Gln27Glu polymorphism has a modulating effect on diet‐induced changes on body weight and body composition, and should be considered in future obesity treatments. These findings should be taken as preliminary and be replicated in further energy restriction studies with larger sample sizes.     

Reduction of 8-iso-prostaglandin F2α in the first week after Roux-en-Y gastric bypass surgery

Obesity is associated with increased markers of oxidative stress. We examined whether oxidative stress is reduced within the first week after Roux‐en‐Y gastric bypass (RYGB) surgery and could be related to changes in adipose tissue depots. The reactive oxygen species (ROS) marker 8‐iso‐prostaglandin F2α (8‐iso‐PGF2α) and activity of antioxidant glutathione peroxidases (GPX) in plasma were compared before and ～1 week after RYGB. The effects of RYGB on subcutaneous adipose tissue and interstitial fluid 8‐iso‐PGF2α levels and subcutaneous adipose tissue expression of GPX‐3 were also assessed. Levels of 8‐iso‐PGF2α in subcutaneous and visceral adipose tissue were determined. Plasma 8‐iso‐PGF2α levels decreased (122 ± 75 to 56 ± 15 pg/ml, P = 0.001) and GPX activity increased (84 ± 18 to 108 ± 25 nmol/min/ml, P = 0.003) in the first week post‐RYGB. RYGB also resulted in reductions of 8‐iso‐PGF2α in subcutaneous adipose tissue (1,742 ± 931 to 1,132 ± 420 pg/g fat, P = 0.046) and interstitial fluid (348 ± 118 to 221 ± 83 pg/ml, P = 0.046) that were comparable to plasma (26–33%, P = 0.74). Adipose GPX‐3 expression was increased (6.7 ± 4.7‐fold, P = 0.004) in the first postoperative week. The improvements in oxidative stress occurred with minimal weight loss (2.4 ± 3.4%, P = 0.031) and elevations in plasma interleukin‐6 (18.0 ± 46.8 to 28.0 ± 58.9 pg/ml, P = 0.004). Subcutaneous and visceral adipose tissues express comparable 8‐iso‐PGF2α levels (1,204 ± 470 and 1,331 ± 264 pg/g fat, respectively; P = 0.34). These data suggest that RYGB affects adipose tissue leading to the restoration of adipose redox balance within the first postoperative week and that plasma 8‐iso‐PGF2α is primarily derived from subcutaneous adipose tissue.     

Low Plasma Leptin Concentration and Low Rates of Fat Oxidation in Weight‐Stable Post‐Obese Subjects

Objective: A low resting metabolic rate for a given body size and composition, a low rate of fat oxidation, low levels of physical activity, and low plasma leptin concentrations are all risk factors for body weight gain. The aim of the present investigation was to compare resting metabolic rate (RMR), respiratory quotient (RQ), levels of physical activity, and plasma leptin concentrations in eight post‐obese adults (2 males and 6 females; 48.9 ± 12.2 years; body mass index [BMI]: 24.5 ± 1.0 kg/m²; body fat 33 ± 5%; mean ± SD) who lost 27.1 ± 21.3 kg (16 to 79 kg) and had maintained this weight loss for ≥2 months (2 to 9 months) to eight age‐ and BMI‐matched control never‐obese subjects (1 male and 7 females; 49.1 ± 5.2 years; BMI 24.4 ± 1.0 kg/m²; body fat 33 ± 7%). Research Methods and Procedures: Following 3 days of weight maintenance diet (50% carbohydrate and 30% fat), RMR and RQ were measured after a 10‐hour fast using indirect calorimetry and plasma leptin concentrations were measured using radioimmunoassay. Levels of physical activity were estimated using an accelerometer over a 48‐hour period in free living conditions. Results: After adjustment for fat mass and fat‐free mass, post‐obese subjects had, compared with controls, similar levels of physical activity (4185 ± 205 vs. 4295 ± 204 counts) and similar RMR (1383 ± 268 vs. 1430 ± 104 kcal/day) but higher RQ (0.86 ± 0.04 vs. 0.81 ± 0.03, p < 0.05). Leptin concentration correlated positively with percent body fat (r = 0.57, p < 0.05) and, after adjusting for fat mass and fat‐free mass, was lower in post‐obese than in control subjects (4.5 ± 2.1 vs. 11.6 ± 7.9 ng/mL, p < 0.05). Discussion: The low fat oxidation and low plasma leptin concentrations observed in post‐obese individuals may, in part, explain their propensity to relapse.     

Water Consumption Increases Weight Loss During a Hypocaloric Diet Intervention in Middle‐aged and Older Adults

Water consumption acutely reduces meal energy intake (EI) among middle‐aged and older adults. Our objectives were to determine if premeal water consumption facilitates weight loss among overweight/obese middle‐aged and older adults, and to determine if the ability of premeal water consumption to reduce meal EI is sustained after a 12‐week period of increased water consumption. Adults (n = 48; 55–75 years, BMI 25–40 kg/m²) were assigned to one of two groups: (i) hypocaloric diet + 500 ml water prior to each daily meal (water group), or (ii) hypocaloric diet alone (nonwater group). At baseline and week 12, each participant underwent two ad libitum test meals: (i) no preload (NP), and (ii) 500 ml water preload (WP). Meal EI was assessed at each test meal and body weight was assessed weekly for 12 weeks. Weight loss was ～2 kg greater in the water group than in the nonwater group, and the water group (β = ?0.87, P < 0.001) showed a 44% greater decline in weight over the 12 weeks than the nonwater group (β = ?0.60, P < 0.001). Test meal EI was lower in the WP than NP condition at baseline, but not at week 12 (baseline: WP 498 ± 25 kcal, NP 541 ± 27 kcal, P = 0.009; 12‐week: WP 480 ± 25 kcal, NP 506 ± 25 kcal, P = 0.069). Thus, when combined with a hypocaloric diet, consuming 500 ml water prior to each main meal leads to greater weight loss than a hypocaloric diet alone in middle‐aged and older adults. This may be due in part to an acute reduction in meal EI following water ingestion.