Labor Saved,Calories Lost: The Energetic Impact of Domestic Labor‐saving Devices

Objective: As the prevalence of obesity has increased, so has sedentariness. Progressive sedentariness has been attributed to greater use of labor saving devices, such as washing machines, and less nonexercise walking (e.g., walking to work). However, there is a paucity of data to support this conclusion. In this study, we address the hypothesis that domestic mechanization of daily tasks has resulted in less energy expenditure compared with performing the same tasks manually. Research Methods and Procedures: Energy expenditure was measured in four groups of subjects (122 healthy adult men and women total) from Rochester, Minnesota. Energy expenditure was measured using indirect calorimetry while subjects performed structured tasks such as cleaning dishes and clothes, stair climbing, and work‐associated transportation, and these values were compared with the respective mechanized activity. Results: Energy expenditure was significantly greater and numerically substantial when daily domestic tasks were performed without the aid of machines or equipment (clothes washing: 45 ± 14 vs. 27 ± 9 kcal/d; dish washing: 80 ± 28 vs. 54 ± 19 kcal/d; transportation to work: 83 ± 17 vs. 25 ± 3 kcal/d; stair climbing: 11 ± 7 vs. 3 ± 1 kcal/d; p < 0.05). The combined impact of domestic mechanization was substantial and equaled 111 kcal/d. Discussion: The magnitude of the energetic impact of the mechanized tasks we studied was sufficiently great to contribute to the positive energy balance associated with weight gain. Efforts focused on reversing sedentariness have the potential to impact obesity.     

Body Composition and Energy Metabolism Following Roux‐en‐Y Gastric Bypass Surgery

Roux‐en‐Y gastric bypass (RYGB) surgery has become an accepted treatment for excessive obesity. We conducted a longitudinal study to assess regional body composition, muscle proteolysis, and energy expenditure before RYGB, and 6 and 12 months after RYGB. Whole‐body and regional fat mass (FM) and lean mass (LM) were assessed via dual energy X‐ray absorptiometry (DXA), and myofibrillar protein degradation was estimated by urinary 3‐methylhistidine (3‐MeH) in 29 subjects. Energy expenditure and substrate oxidation were also determined using a whole‐room, indirect calorimeter in 12 of these subjects. LM loss constituted 27.8 ± 10.2% of total weight loss achieved 12 months postoperatively, with the majority of LM loss (18 ± 6% of initial LM) occurring in the first 6 months following RYGB. During this period, the trunk region contributed 66% of whole‐body LM loss. LM loss occurred in the first 6 months after RYGB despite decreased muscle protein breakdown, as indicated by a decrease in 3‐MeH concentrations and muscle fractional breakdown rates. Sleep energy expenditure (SEE) decreased from 2,092 ± 342 kcal/d at baseline to 1,495 ± 190 kcal/day at 6 months after RYGB (P < 0.0001). Changes in both LM and FM had an effect on the reduction in SEE (P < 0.001 and P = 0.005, respectively). These studies suggest that loss of LM after RYGB is significant and strategies to maintain LM after surgery should be explored.     

Differences in daily energy expenditure in lean and obese women: the role of posture allocation

Objective: A low resting metabolic rate (RMR) is considered a risk factor for weight gain and obesity; however, due to the greater fat‐free mass (FFM) found in obesity, detecting an impairment in RMR is difficult. The purposes of this study were to determine the RMR in lean and obese women controlling for FFM and investigate activity energy expenditure (AEE) and daily activity patterns in the two groups. Methods and Procedures: Twenty healthy, non‐smoking, pre‐menopausal women (10 lean and 10 obese) participated in this 14‐day observational study on free‐living energy balance. RMR was measured by indirect calorimetry; AEE and total energy expenditure (TEE) were calculated using doubly labeled water (DLW), and activity patterns were investigated using monitors. Body composition including FFM and fat mass (FM) was measured by dual energy X‐ray absorptiometry (DXA). Results: RMR was similar in the obese vs. lean women (1601 ± 109 vs. 1505 ± 109 kcal/day, respectively, P = 0.12, adjusting for FFM and FM). Obese women sat 2.5 h more each day (12.7 ± 3.2 h vs. 10.1 ± 2.0 h, P < 0.05), stood 2 h less (2.7 ± 1.0 h vs. 4.7 ± 2.2 h, P = 0.02) and spent half as much time in activity than lean women (2.6 ± 1.5 h vs. 5.4 ± 1.9 h, P = 0.002). Discussion: RMR was not lower in the obese women; however, they were more sedentary and expended less energy in activity than the lean women. If the obese women adopted the activity patterns of the lean women, including a modification of posture allocation, an additional 300 kcal could be expended every day.     

Mitochondrial fission: firing up mitochondria in brown adipose tissue

Brown adipose tissue (BAT) is an important site for energy expenditure, for instance to generate heat in times of cold exposure. BAT expansion and activation can increase energy dissipation of an organism. This involves the coordinated activation of mitochondrial metabolism and heat generation through uncoupling of oxidative phosphorylation. In this issue of The EMBO Journal, the Shirihai group uncovers a novel potentiation pathway for BAT energy expenditure. Changes in mitochondrial dynamics, in particular mitochondrial fission, act in synergy with fatty acid‐induced uncoupling to activate BAT metabolism in response to the hormone norepinephrine.     

Lower critical temperature and cold-induced thermogenesis of lean and overweight humans are inversely related to body mass and basal metabolic rate

It is colloquially stated that body size plays a role in the human response to cold, but the magnitude and details of this interaction are unclear. To explore the inherent influence of body size on cold-exposed metabolism, we investigated the relation between body composition and resting metabolic rate in humans at thermoneutrality and during cooling within the nonshivering thermogenesis range. Body composition and resting energy expenditure were measured in 20 lean and 20 overweight men at thermoneutrality and during individualized cold exposure. Metabolic rates as a function of ambient temperature were investigated considering the variability in body mass and composition. We observed an inverse relationship between body size and the lower critical temperature (LCT), i.e. the threshold where thermoneutrality ends and cold activates thermogenesis. LCT was higher in lean than overweight subjects (22.1 ± 0.6 vs 19.5 ± 0.5 °C, p < 0.001). Below LCT, minimum conductance was identical between lean and overweight (100 ± 4 vs 97 ± 3 kcal/°C/day respectively, p = 0.45). Overweight individuals had higher basal metabolic rate (BMR) explained mostly by the higher lean mass, and lower cold-induced thermogenesis (CIT) per degree of cold exposure. Below thermoneutrality, energy expenditure did not scale to lean body mass. Overweight subjects had lower heat loss per body surface area (44.7 ± 1.3 vs 54.7 ± 2.3 kcal/°C/m²/day, p < 0.001). We conclude that larger body sizes possessed reduced LCT as explained by higher BMR related to more lean mass rather than a change in whole-body conductance. Thus, larger individuals with higher lean mass need to be exposed to colder temperatures to activate CIT, not because of increased insulation, but because of a higher basal heat generation. Our study suggests that the distinct effects of body size and composition on energy expenditure should be taken in account when exploring the metabolism of humans exposed to cold.     

Influence of Sibutramine on Energy Expenditure in African American Women

Objective: African American women have a high prevalence of obesity, which partially may be explained by their lower rates of resting energy expenditure (REE). The aim of this study was to examine the influence of acute sibutramine administration on REE and post‐exercise energy expenditure in African American women. Research Methods and Procedures: A total of 15 premenopausal, African American women (age, 29 ± 5 years; body fat, 38 ± 7%) completed a randomized, double‐blind cross‐over design with a 30‐mg ingestion of sibutramine or a placebo. Each trial was completed a month apart in the follicular phase and included a 30‐minute measurement of REE 2.5 hours after sibutramine or placebo administration. This was followed by 40 minutes of cycling at ～70% of peak aerobic capacity and a subsequent 2‐hour measurement of post‐cycling energy expenditure. Results: There was no difference (p > 0.05) in REE (23.70 ± 2.81 vs. 23.69 ± 2.95 kcal/30 min), exercise oxygen consumption (1.22 ± 0.15 vs. 1.25 ± 0.15 liter/min), and post‐cycling energy expenditure (104.2 ± 12.7 vs. 104.9 ± 11.4 kcal/120 min) between the sibutramine and placebo trials, respectively. Cycling heart rate was significantly higher (p = 0.01) during the sibutramine (158 ± 14 beats/min) vs. placebo (150 ± 12 beats/min) trials. Discussion: These data demonstrate that acute sibutramine ingestion does not increase REE or post‐exercise energy expenditures but does increase exercising heart rate in overweight African American women. Sibutramine may, therefore, impact weight loss through energy intake and not energy expenditure mechanisms.     

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.     

Functional Imaging of Brown Fat in Mice with 18F-FDG micro-PET/CT

Brown adipose tissue (BAT) differs from white adipose tissue (WAT) by its discrete location and a brown-red color due to rich vascularization and high density of mitochondria. BAT plays a major role in energy expenditure and non-shivering thermogenesis in newborn mammals as well as the adults ¹. BAT-mediated thermogenesis is highly regulated by the sympathetic nervous system, predominantly via β adrenergic receptor ^{2, 3}. Recent studies have shown that BAT activities in human adults are negatively correlated with body mass index (BMI) and other diabetic parameters ^4-6. BAT has thus been proposed as a potential target for anti-obesity/anti-diabetes therapy focusing on modulation of energy balance ^6-8. While several cold challenge-based positron emission tomography (PET) methods are established for detecting human BAT ^9-13, there is essentially no standardized protocol for imaging and quantification of BAT in small animal models such as mice. Here we describe a robust PET/CT imaging method for functional assessment of BAT in mice. Briefly, adult C57BL/6J mice were cold treated under fasting conditions for a duration of 4 hours before they received one dose of ¹⁸F-Fluorodeoxyglucose (FDG). The mice were remained in the cold for one additional hour post FDG injection, and then scanned with a small animal-dedicated micro-PET/CT system. The acquired PET images were co-registered with the CT images for anatomical references and analyzed for FDG uptake in the interscapular BAT area to present BAT activity. This standardized cold-treatment and imaging protocol has been validated through testing BAT activities during pharmacological interventions, for example, the suppressed BAT activation by the treatment of β-adrenoceptor antagonist propranolol ^{14, 15}, or the enhanced BAT activation by β3 agonist BRL37344 ¹⁶. The method described here can be applied to screen for drugs/compounds that modulate BAT activity, or to identify genes/pathways that are involved in BAT development and regulation in various preclinical and basic studies.     

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.     

Influence of Short‐Term Consumption of the Caffeine‐Free,Epigallocatechin‐3‐Gallate Supplement,Teavigo, on Resting Metabolism and the Thermic Effect of Feeding

Green tea is purported to promote weight loss. Resting metabolic rate (RMR) and the thermic effect of feeding (TEF) are significant components of total daily energy expenditure and are partially determined by the sympathetic nervous system via catecholamine‐mediated stimulation of β‐adrenergic receptors. Epigallocatechin‐3‐gallate (EGCG: the most bioactive catechin in green tea) inhibits catechol‐O‐methyltransferase, an enzyme contributing to the degradation of catecholamines. Accordingly, we hypothesized that short‐term consumption of a commercially available EGCG supplement (Teavigo) augments RMR and TEF. On two separate occasions, seven placebo or seven EGCG capsules (135 mg/capsule) were administered to 16 adults (9 males, 7 females, age 25 ± 2 years, BMI 24.6 ± 1.2 kg/m² (mean ± s.e.)). Capsules (three/day) were consumed over 48 h; the final capsule was consumed 2 h prior to visiting the laboratory. Energy expenditure (ventilated hood technique) was determined at rest and for 5 h following ingestion of a liquid meal (caloric content: 40% RMR). Contrary to our hypothesis, RMR was not greater (P = 0.10) following consumption of EGCG (6,740 ± 373 kJ/day) compared with placebo (6,971 ± 352). Similarly, the area under the TEF response curve (Δ energy expenditure) was also unaffected by EGCG (246,808 ± 23,748 vs. 243,270 ± 22,177 kJ; P = 0.88). EGCG had no effect on respiratory exchange ratio at rest (P = 0.29) or throughout the TEF measurement (P = 0.56). In summary, together RMR and TEF may account for up to 85% of total daily energy expenditure; we report that short‐term consumption of a commercially available EGCG supplement did not increase RMR or TEF.     

Arg64β3‐Adrenoceptor Variant and the Components of Energy Expenditure

Objective: To determine Trp64Arg β₃‐adrenoceptor genotype‐specific differences in the components of energy expenditure. Hypothesis: We hypothesized that resting metabolic rate (RMR) and physical activity levels would be lower and that thermic effect of feeding (TEF) would be higher in those with the Arg64 allele. Research Methods and Procedures: RMR and TEF were measured by indirect calorimetry, physical activity by questionnaire, and total energy expenditure by the doubly labeled water method. Genotype‐specific measures were compared using ANOVA and analysis of covariance (ANCOVA). Results: RMR in Arg64 homozygotes was significantly lower than in Trp64 homozygotes [Arg64, 1373 ± 259 kcal/d (n = 15) vs. Trp64Arg, 1538 ± 238 kcal/d (n = 25) vs. Trp64, 1607 ± 290 kcal/d (n = 22); p < 0.01]. TEF was significantly higher in Arg64 homozygotes compared with Trp64 homozygotes (Arg64, 359 ± 28 kcal/d; Trp64Arg, 322 ± 22 kcal/d; and Trp64, 279 ± 23 kcal/d; p < 0.05). No differences were identified between genotypes in physical activity or in total energy expenditure. Discussion: Our results suggest that the Arg64 β₃‐adrenoceptor allele contributes significantly to the genetic variability in both RMR and TEF.     

Different metabolic responses of human brown adipose tissue to activation by cold and insulin

We investigated the metabolism of human brown adipose tissue (BAT) in healthy subjects by determining its cold-induced and insulin-stimulated glucose uptake and blood flow (perfusion) using positron emission tomography (PET) combined with computed tomography (CT). Second, we assessed gene expression in human BAT and white adipose tissue (WAT). Glucose uptake was induced 12-fold in BAT by cold, accompanied by doubling of perfusion. We found a positive association between whole-body energy expenditure and BAT perfusion. Insulin enhanced glucose uptake 5-fold in BAT independently of its perfusion, while the effect on WAT was weaker. The gene expression level of insulin-sensitive glucose transporter GLUT4 was also higher in BAT as compared to WAT. In conclusion, BAT appears to be differently activated by insulin and cold; in response to insulin, BAT displays high glucose uptake without increased perfusion, but when activated by cold, it dissipates energy in a perfusion-dependent manner.     

Effects of acute and chronic protein intake on metabolism, appetite, and ghrelin during weight loss

Objective: This study evaluated the effects of acute and chronic consumption of higher dietary protein on energy expenditure, macronutrient use, appetite, and appetite‐regulating hormones during weight loss in women. Research Methods and Procedures: Thirty‐eight women chronically consuming a 750 kcal/d energy‐deficit diet with a protein content of 30% (higher protein‐chronic diet, HP‐CD, n = 21) or 18% (normal protein‐chronic diet, NP‐CD, n = 17) for 9 weeks were tested. On separate days, metabolic, appetite, and hormonal responses were measured over 4 hours when the women consumed a higher protein‐acute meal (HP‐AM) (30% of energy as protein) or a normal protein‐acute meal (NP‐AM) (18% of energy as protein). Results: With chronic diet groups combined, HP‐AM led to lower respiratory exchange ratio (0.829 ± 0.005 vs. 0.843 ± 0.008; p < 0.05), lower carbohydrate oxidation (p < 0.05), and higher fat oxidation (p < 0.05) compared with NP‐AM. HP‐AM also led to reduced self‐reported postprandial hunger (p < 0.001) and desire to eat (p < 0.001) and lower postprandial ghrelin (252 ± 16 vs. 274 ± 18 ng/mL · 240 minutes, p < 0.05) compared with NP‐AM. No differences in postprandial energy expenditure (PPEE) occurred between meals. When combining acute meals, respiratory exchange ratio was lower (p < 0.05) and protein oxidation (p < 0.001) was higher in the HP‐CD vs. NP‐CD. An acute meal‐by‐chronic diet interaction was observed with PPEE such that HP‐AM led to greater PPEE in the HP‐CD vs. NP‐CD (28.7 ± 2.7 vs. 19.9 ± 2.7 kcal/min for 195 minutes; p < 0.05). Conclusions: During weight loss, thermogenesis and protein use appear to be influenced by chronic protein intake, while appetite and ghrelin are more responsive to acute protein intake.     

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.     

Calcium and dairy product modulation of lipid utilization and energy expenditure

Objective: The purpose of this study was to investigate the impact of dietary calcium or dairy product intake on total energy expenditure (TEE), fat oxidation, and thermic effect of a meal (TEM) during a weight loss trial. Methods and Procedures: The intervention included a prescribed 500‐kcal deficit diet in a randomized placebo‐controlled calcium or dairy product intervention employing twenty‐four 18 to 31‐year‐old (22.2 ± 3.1 years, mean ± s.d.) overweight women (75.5 ± 9.6 kg). TEM and fat oxidation were measured using respiratory gas exchange after a meal challenge, and TEE was measured by doubly labeled water. Fat mass (FM) and lean mass (fat‐free mass (FFM)) were measured by dual‐energy X‐ray absorptiometry. Subjects were randomized into one of these three intervention groups: (i) placebo (<800 mg/day calcium intake); (ii) 900 mg/day calcium supplement; (iii) three servings of dairy products/day to achieve an additional 900 mg/day. Results: There were no group effects observed in change in TEE; however, a group effect was observed for fat oxidation after adjusting for FFM (P = 0.02). The treatment effect was due to an increase in fat oxidation in the calcium‐supplemented group of 1.5 ± 0.6 g/h, P = 0.02. Baseline 25‐hydroxyvitamin D (25OHD) was positively correlated with TEM (R = 0.31, P = 0.004), and trended toward a correlation with fat oxidation (P = 0.06), independent of group assignment. Finally, the change in log parathyroid hormone (PTH) was positively correlated with the change in trunk FM (R = 0.27, P = 0.03). Discussion: These results support that calcium intake increases fat oxidation, but does not change TEE and that adequate vitamin D status may enhance TEM and fat oxidation.     

Thermoregulatory control of feeding and sleep in premature infants

Objective: The aim of the present study was to test the thermoregulatory feeding control hypothesis in sleeping, premature infants. Research Methods and Procedures: In premature infants, the energy supply from food intake is crucial for (in order of importance): organ operation, body homeothermia, and optimal growth. The Himms‐Hagen model of thermoregulatory feeding control involving activation of heat production by brown adipose tissue (BAT) was formulated on the basis of work in (awake) rats. This hypothesis has also been put forward for the human neonate, which can also use BAT to produce metabolic heat. According to the model, feeding episodes occur during a transient increase in body temperature. Feeding is initiated by a dip in blood glucose concentration after sugar uptake by activated BAT. Results: In 14 neonates (bottle‐fed on demand), food intake always took place during an increase in skin temperature (+0.19 ± 0.21 °C). Awakening occurred 18 ± 17 minutes after the minimum skin temperature level had been reached. When feeding time was imposed, feeding was not necessarily situated during an increase in skin temperature, and the sleep duration after food intake increased significantly (+43%). This could be considered as an adaptive response to the short‐term sleep deprivation and/or stress elicited by an imposed feeding rhythm. Discussion: The validity of the model supports the use of on‐demand feeding in neonatal care units, in accordance with the infant's physiological body temperature oscillations.     

Infrared thermographic calorimetry applied to preterm infants under radiant warmers

Infrared thermographic calorimetry uses an infrared camera and heat loss equations as a non-invasive method to obtain the energy expenditure of humans. This study focused on preterm infants under radiant warmers, and physiological changes the infants underwent when the radiant heat source was removed. Ten infants with a mean weight of 1.88±1.29 kg (±=SD) showed a mean energy expenditure of 3.08±0.55 kcal kg⁻¹ h⁻¹. When the warmer was removed for 2 min and 30 s, heat loss increased to 6.50±1.07 kcal kg⁻¹ h⁻¹ and mean body temperature dropped by 1.0±0.3°C. Thirty seconds after the warmer was returned, mean body surface temperature and heat loss returned to original levels.     

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.     

The Effects of Consuming Frequent,Higher Protein Meals on Appetite and Satiety During Weight Loss in Overweight/Obese Men

The purpose of this study was to determine the effects of dietary protein and eating frequency on perceived appetite and satiety during weight loss. A total of 27 overweight/obese men (age 47 ± 3 years; BMI 31.5 ± 0.7 kg/m²) were randomized to groups that consumed an energy‐restriction diet (i.e., 750 kcal/day below daily energy need) as either higher protein (HP, 25% of energy as protein, n = 14) or normal protein (NP, 14% of energy as protein, n = 13) for 12 weeks. Beginning on week 7, the participants consumed their respective diets as either 3 eating occasions/day (3‐EO; every 5 h) or 6 eating occasions/day (6‐EO; every 2 h), in randomized order, for 3 consecutive days. Indexes of appetite and satiety were assessed every waking hour on the third day of each pattern. Daily hunger, desire to eat, and preoccupation with thoughts of food were not different between groups. The HP group experienced greater fullness throughout the day vs. NP (511 ± 56 vs. 243 ± 54 mm · 15 h; P < 0.005). When compared to NP, the HP group experienced lower late‐night desire to eat (13 ± 4 vs. 27 ± 4 mm, P < 0.01) and preoccupation with thoughts of food (8 ± 4 vs. 21 ± 4 mm; P < 0.01). Within groups, the 3 vs. 6‐EO patterns did not influence daily hunger, fullness, desire to eat, or preoccupation with thoughts of food. The 3‐EO pattern led to greater evening and late‐night fullness vs. 6‐EO but only within the HP group (P < 0.005). Collectively, these data support the consumption of HP intake, but not greater eating frequency, for improved appetite control and satiety in overweight/obese men during energy restriction‐induced weight loss.