Influence of weight-loss diets with different macronutrient compositions on health-related quality of life in obese youth

The aims of this study were to compare the effects of weight-loss diets of different macronutrient compositions on weight and health-related quality of life (HRQOL), and to examine the relationship between changes in HRQOL parameters and weight loss during weight-loss programs in obese adolescents. Seventy one adolescents (12-18 years, BMI>95th percentile) were randomly allocated to one of three 12-week diet regimens: low-carbohydrate low-fat (LCLF), low-carbohydrate high-fat (LCHF) or high-carbohydrate low-fat (HCLF) diets. Weight, height and fat-mass were measured, and the PedsQL 4.0 questionnaires were administered to the participants at baseline and at the end of the intervention. Significant similar reductions in BMI, BMI-SDS, and fat percentage occurred in all groups. A significant improvement in HRQOL was found only in the LCLF and HCLF groups. For the entire sample, positive correlations were found between emotional and psychosocial functioning at baseline and the reduction in BMI, BMI-SDS, and fat percentage. By multiple regression analysis, higher baseline emotional functioning and BMI-SDS were significant predictors to higher reduction in BMI-SDS during the intervention. Our results support the importance of evaluating and improving psychosocial functioning before initiation of a weight-loss intervention program in adolescents, and the importance of low-fat diets in weight-loss interventions for adolescents.     

Meal-induced thermogenesis and macronutrient oxidation in lean and obese women after consumption of carbohydrate-rich and fat-rich meals

Objective

To examine differences in meal-induced thermogenesis and macronutrient oxidation between lean and obese women after consumption of two different isocaloric meals, one rich in carbohydrate (CHO) and one rich in fat.

Methods

A total of 19 lean and 22 obese women were studied on two occasions, 1 wk apart. In one visit they consumed a CHO-rich meal and in the other visit a fat-rich meal. The two meals were isocaloric and were given in random order. Resting energy expenditure and macronutrient oxidation rates were measured and calculated in the fasting state and every hour for 3 h after meal consumption.

Results

Meal-induced thermogenesis was not different between lean and obese subjects after the CHO-rich (P = 0.89) or fat-rich (P = 0.32) meal, but it was significantly higher after the CHO-rich compared with the fat-rich meal in the lean and the obese individuals (P < 0.05). Protein oxidation rate increased slightly but significantly after the test meals in both groups (P < 0.01). Fat oxidation rate decreased after consumption of the CHO-rich meal (P < 0.001), whereas it increased after consumption of the fat-rich meal in both groups (P < 0.01). CHO oxidation rate increased in both groups after consumption of the CHO-rich meal (P < 0.001). Oxidation rates of protein, fat, and CHO during the experiment were not significantly different between lean and obese participants.

Conclusion

Meal-induced thermogenesis and macronutrient oxidation rates were not significantly different between lean and obese women after consumption of a CHO-rich or a fat-rich meal.     

Skeletal muscle function and metabolism in obese women

A possible mechanism to regulate body weight during a high calorie intake may be an increased metabolic rate in skeletal muscle. To approach this hypothesis the energy metabolites, ATP, phosphocreatine, creatine, glycogen and lactate were measured in biopsies from the quadriceps femoris muscle. Concomitantly the function of the adductor pollicis muscle was studied as assessed after electrical stimulation of the ulnar nerve. The muscle function variables were, force of contraction at 5, 10, 20, and 50 Hz of stimulation, relaxation rate, and endurance. Eight obese women were studied before gastroplastic surgery and 6 months postoperatively and a weight loss of 19.4 +/- 3.4% (mean +/- SEM). Preoperatively ATP, phosphocreatine, glycogen, and lactate were significantly decreased and the same pattern was found postoperatively. These findings can be related to a low production of energy-rich phosphates or a high energy utilization. Both pre- and postoperatively there was, a decreased force of contraction at 10 Hz of stimulation (p less than 0.001), a faster relaxation rate (p less than 0.01) and a normal endurance. These functional results indicate a high metabolic rate. At admission a decreased serum insulin level indicated a moderate insulin resistance which was normalized after the weight loss. The triiodothyronine concentration was normal before and after operation. In conclusion our findings of changed muscle energy metabolite concentrations and altered muscle function indicate a high metabolic rate in skeletal muscle in obese women. This may be an adaptation in skeletal muscle energy metabolism to a high body weight.     

Oxidative and nonoxidative macronutrient disposal in lean and obese men after mixed meals.

Oxidative and nonoxidative macronutrient disposal rates were measured in lean and obese males randomly fed mixed meals containing 0, 33, 67, 100, and 134 kJ/kg fat-free mass (0, 8, 16, 24, and 32 kcal/kg). Body composition, preprandial and postprandial energy expenditure, and macronutrient concentrations in the extracellular space were measured. Relationships among carbohydrate, fat, and protein disposal rates; body weight; and body composition were examined. Oxidative and nonoxidative disposals of macronutrients were not different between the lean and obese groups. Glucose was preferentially oxidized and fat was preferentially stored after nutrient ingestion. Macronutrient storage increased linearly with caloric intake. Oxidative and nonoxidative macronutrient disposals were completed within 8 h after ingesting the meals. Serum insulin concentrations rose to 3000-6000 pmol/L in two obese men after their two largest meals. Eight hours after nutrient ingestion, concentrations of macronutrient substrates, metabolic products, and insulin were indistinguishable from preprandial values.     

Time-course changes in macronutrient metabolism induced by a nutritionally balanced low-calorie diet in obese women

The use of low-calorie diets is a common strategy for body-weight reduction purposes, but the time-course of the metabolic changes induced by moderately energy-restricted, otherwise balanced, diets is still poorly known. The aim of this nutritional intervention design was to study in obese women the effect of a balanced low-calorie diet on the metabolic rate, and metabolic fuel utilization changes during the weight loss process through the application of breath tests with stable isotope-labeled tracers. Seven obese (body mass index >30 kg/m(2)) women were assigned to a 10-week dietary hypoenergetic intervention regime supplying 55% of energy as carbohydrate, 30% as fat and 15% as protein. Metabolic rate and substrate utilization were evaluated for 6 h in separate occasions during the weight loss program by indirect calorimetry and after 13C-labeled glucose, triolein and leucine administration. Body weight loss after 10 weeks was 4.2+/-1.1 kg, while the percent body fat decrease was about 5%. Slimming was accompanied by a marked decrease in fasting leptin (about 25%). Postprandial carbohydrate utilization after the administration of a test meal with the same macronutrient distribution as the experimental low-energy diet was decreased (24.1%, P<0.05) as a consequence of the dietary restriction, which was associated with lower insulin plasma levels (P<0.05). Although protein and lipid oxidation were not significantly different after weight reduction (day 1 versus day 70), the metabolic utilization of these substrates tended to increase. Moreover, marginally significant indications obtained on days 15 and 45 suggest that the weight and body composition changes are attributable to a shift in endogenous and exogenous glucose utilization in favor of lipid burning. The breath tests determinations, which were performed on different occasions along the experimental trial, confirmed that the cumulative 13C output decreased for labeled tracers with time, being only statistically significant for the glucose utilization between days 15 and 45. In summary, the weight and fat mass losses were associated with a lower carbohydrate oxidation, which were probably compensated by an increase in lipid oxidation without major changes in protein mobilization.     

Basal and postprandial substrate oxidation rates in obese women receiving two test meals with different protein content

BACKGROUND & AIMS: Fuel utilisation and storage in lean and obese subjects seem to be differently affected by the macronutrient distribution intake. The aim of this intervention study was to explore the extent to which the fat mass status and the macronutrient composition of an acute dietary intake influence substrate oxidation rates. METHODS: Fuel utilisation in 26 women, 14 obese (BMI = 37.1 +/- 1.1 kg/m2) and 12 lean (BMI = 20.6 +/- 0.5 kg/m2) was measured over 6 h to compare the metabolic effect of a single balanced protein (HC) meal and a high protein (HP) single meal, which were designed to supply similar energy contents (1672 kJ). The macronutrient composition as a percentage of energy of the HC meal was 55% carbohydrate, 15% protein and 30% fat, while the HP meal contained 40% carbohydrate, 30% protein and 30% fat. Nutrient oxidation rates and energy expenditure were calculated by indirect calorimetry (hood system), whereas exogenous amino acid oxidation was estimated from the 13C isotopic enrichment of breath after oral administration of L[1-13C]leucine. RESULTS: Fasting lipid oxidation was higher in the obese than in the lean women (P < 0.05), and it was significantly correlated with body fatness (P < 0.01). A single HP meal consumption produced higher postprandial fat oxidation as compared with HC meal intake (P < 0.02), in both obese and lean subjects, with no apparent changes in glucose oxidation rates. Furthermore, postprandial fat utilisation after the test meal intake was higher in obese than in the lean women (P < 0.01). The time course of 13CO2 in breath followed a similar pattern in both dietary groups, although a non-statistically significant higher trend in protein and 13C-leucine oxidation was found in the HP group. CONCLUSIONS: Net lipid oxidation depends on both short-term dietary composition intake and fat body mass, being significantly higher after a relatively high protein meal as compared to a balanced diet intake and in obese women as compared to lean controls.     

Effect of weight loss on bone metabolism in postmenopausal obese women with osteoarthritis

BackgroundThe choice of hypocaloric diets in obesity can affect bone health.AimsThe aim of this study is to assess the effect of a hypocaloric diet in postmenopausal obese women and to determine the influence of weight reduction on bone metabolism.MethodsThis was a non-randomised, single-treatment study in 96 postmenopausal women with a body mass index (BMI) greater than 35 kg/m² and osteoarthritis. The patients received a formula diet with two intake levels of a normocaloric hyperproteic formula (1035 kcal (25% protein)). Anthropometry and biochemistry with CrossLaps, osteocalcin, parathyroid hormone (PTH) and 25-OH vitamin D were measured. Consumption of protein, calcium and vitamin D were determined at the beginning of and 3 and 6 months into the study. The response to treatment was compared (high-responder (HR): weight loss greater than 15%, and low-responder (LR): weight loss less than 15%).ResultsThe mean age was 64.2 (7.5) years. After 6 months of treatment, a weight loss of 10.2% (8.2–13.8) was observed. There was a significant increase in vitamin D (HR: 21.8% (36.2) vs. LR: 22.7% (36.9), p = 0.93) and CrossLaps (HR: 26.8% (19.5–35.2)) vs. LR: 13.3% (?6.1 to 27.9), p = 0.01). The loss of more than 15% of initial body weight was an independent risk factor for an increase in CrossLaps (OR: 4.22 (1.1–16.8), p = 0.04).ConclusionsIn postmenopausal obese women, weight loss was associated with an increase in the biochemical parameters of bone resorption. The increase in resorption parameters was related to the magnitude of weight loss.     

Effect of weight loss on the postprandial response to high-fat and high-carbohydrate meals in obese women

OBJECTIVE: To assess the effect of weight loss on the plasma lipid and remnant-like lipoprotein cholesterol (RLPc) response to a high-fat or a high-carbohydrate meal in a population of obese women. DESIGN: Nutritional intervention study. SUBJECTS: Sixteen obese women (mean body mass index (BMI): 37.6+/-5 kg/m(2)). METHODS: Subjects were asked to follow an energy-restricted diet (800 kcal/day) for 7 weeks, followed by a 1-week maintenance diet. Before and after weight loss, each participant was given (in random order) two iso-energetic meals containing either 80% fat and 20% protein (the high-fat meal) or 80% carbohydrate and 20% protein (the high-carbohydrate meal). Blood samples were collected over the following 10-h period. A two-way analysis of variance with repeated measures was used to assess the effect of the meal and postprandial time on biological variables and postprandial responses (notably RLPc levels). RESULTS: Weight loss was associated with a significant decrease in fasting triglyceride (P=0.0102), cholesterol (P<0.0001), low-density lipoprotein cholesterol (P=0.0003), high-density lipoprotein-cholesterol (P=0.0009) and RLPc (P=0.0015) levels. The triglyceride response to the high-fat meal was less intense after weight reduction than before (interaction P<0.002). This effect persisted after adjustment on baseline triglyceride levels. The triglyceride response to the high-carbohydrate meal was biphasic (i.e. with two peaks, 1 and 6 h after carbohydrate intake). After adjustment on baseline values, weight reduction was associated with a trend towards a reduction in the magnitude of the second triglyceride peak (interaction P<0.054). In contrast, there was no difference in postprandial RLPc responses before and after weight loss, again after adjustment on baseline levels. CONCLUSION: Our data suggest that weight loss preferentially affects postprandial triglyceride metabolism.     

Body fat distribution and energy metabolism in obese men and women.

Upper body obesity seems to be associated with a better prognosis for weight loss than does lower body obesity. However, the impact of body fat distribution on energy metabolism is not clear.

One hundred fifteen non-diabetic obese Caucasians (64 males and 51 females) and 108 Caucasian lean controls (82 males and 26 females) were studied.

Body composition was assessed by hydrodensitometry and body fat distribution was estimated by the waist-to-thigh circumference ratio (W/T). Values of 24-hour energy expenditure (24h-EE), basal metabolic rate (BMR), sleeping metabolic rate (SMR) and respiratory quotient (RQ) were measured in a respiration chamber.

BMR, adjusted for differences in fat-free mass, fat mass, age and sex, correlated with W/T in obese males (r = 0.40; p < 0.01), but not in obese females. Obese male subjects with upper body obesity had BMR significantly higher than those with lower body obesity (2189 +/? 268 vs 1974 +/? 141 kcal/day; p < 0.01), independently of differences in fat-free mass, fat mass and age. No correlations were found between W/T and adjusted 24h-EE, SMR or RQ in all examined groups.

These findings indicate that in obese males, upper body obesity is associated with increased metabolic rate, possibly related to higher levels of lipid turnover in visceral fat.     

Short-term effects of a hypocaloric diet on nitrogen excretion in morbid obese women

OBJECTIVE: To determine whether the daily pattern of urine excretion of N wastes is affected by obesity and very low-calorie diets (VLCD). DESIGN: The plasma amino acid, urea and other energy parameters, as well as the urinary excretion of total nitrogen, urea and creatinine were studied in obese and normal-weight women. The obese women's data were obtained under hospital basal controlled conditions (8.1 MJ/day) and after 3 days of VLCD diet (1.9 MJ/day) controls were studied only once (5.8 MJ/day). The hourly excretion patterns of total N, urea and creatinine were determined from the composition of each bladder voiding. SUBJECTS: Twenty morbidly obese and 10 age-matched normal-weight control women. RESULTS: Plasma amino acid levels were higher in obese women, which showed a limited ability to metabolize amino acid hydrocarbon skeletons. Neither differences in the patterns between groups nor total 24 h values for urine volume were found. Total N and urea excretion diminished under VLCD diet. Hourly creatinine excretion showed a flat pattern and was higher in obese women than in the controls, VLCD diet diminished the amount of creatinine excreted in 24 h. CONCLUSIONS: The early change in energy availability that the creatinine excretion figures reflect may result from the energy conservation mechanisms induced in response to energy restriction. The early onset of this effect (3 days, and the extent of decrease (approximately 19%) also suggest that the impact of VLCD on the muscle energy budget of the obese is more marked than usually assumed.     

Effect of a hypocaloric diet on serum visfatin in obese non-diabetic patients

OBJECTIVE: Obesity and insulin resistance are associated with classic and new cardiovascular risk factors, such as inflammatory markers and adipocytokines. The aim of this study was to examine whether weight reduction could change visfatin serum concentrations in obese patients. METHODS: This was an interventional longitudinal study analyzing a population of 80 obese non-diabetic outpatients. Weight, blood pressure, fasting serum glucose, C-reactive protein, plasma insulin, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triacylglycerols, and insulin resistance (homeostatic model assessment) were measured before and after 3 mo on a hypocaloric diet. RESULTS: Eighty patients were enrolled. The mean age was 46.7 +/- 16.7 y, the mean body mass index was 34.1 +/- 4.8 kg/m(2), with 20 men (25%) and 60 women (75%). After 3 mo on a hypocaloric diet, body mass index, fat mass, waist circumference, systolic blood pressure, fasting serum glucose, total cholesterol, and low-density lipoprotein cholesterol decreased. The serum concentration of visfatin decreased with weight loss (112.14 +/- 70.2 versus 99.4 +/- 58.1 ng/mL, P < 0.05). In the multivariate analysis of visfatin concentration before and after treatment, as a dependent variable, only age remained an independent predictor in the model (F = 12.5, P < 0.02), with an inverse correlation: visfatin decreased 4.1 g/mL (F = 12.5, P < 0.05) and 3.7 g/mL (95% confidence interval 1.2-6.1), respectively, for each year of age. CONCLUSION: Weight reduction after a 3-mo period of a hypocaloric diet is associated with a significant decrease in circulating serum concentrations of the novel adipokine visfatin in obese subjects. Visfatin is inversely correlated with age.     

Postprandial leptin response to carbohydrate and fat meals in obese women

OBJECTIVE: To assess the postprandial leptin responses to a carbohydrate and a fatty meal in obese subjects and its association with postprandial insulin response. METHODS: Eight obese and 11 lean women were given, in a random order, an isocaloric carbohydrate meal (3.43 MJ, 166g of carbohydrates, 38g of proteins) or fat meal (3.35 MJ, 70g of fat, 36g of proteins) or remained fasting. Blood samples were collected hourly during the nine hours after the meal for leptin, insulin, C-peptide and glucose determinations. RESULTS: In obese subjects, as in lean subjects, postprandial leptin response, calculated as the increment above fasting values, was higher after the carbohydrate meal than after the fatty meal (p < 0.01). However, after the carbohydrate meal, postprandial leptin increment was lower (p < 0.05) in obese subjects than in lean controls. In contrast, there was no difference in postprandial leptin response between lean and obese subjects after the fatty meal. Correlation analyses showed that the area under the postprandial leptin response curve (leptin AUC) was correlated to insulin AUC in lean (r = 0.70, p < 0.01), but not in obese subjects. CONCLUSION: These results indicate that postprandial leptin response is lower after a carbohydrate meal in obese women than in lean controls, suggesting an impairment of postprandial leptin regulation in obese women.     

Effects of red pepper added to high-fat and high-carbohydrate meals on energy metabolism and substrate utilization in Japanese women

The effects of dietary red pepper added to high-fat (HF) and high-carbohydrate (HC) meals on energy metabolism were examined in thirteen Japanese female subjects. After ingesting a standardized dinner on the previous evening, the subjects took an experimental breakfast (1883 kJ) under the following four conditions: HF meal, HF and red-pepper (10 g) meal, HC meal, or HC and red-pepper meal. Palatability of the experimental meals was measured immediately after the meals. Expired air was collected before and for 210 min after the meal to determine energy expenditure and macronutrient oxidation. Diet-induced thermogenesis was significantly higher after the HC meals than after the HF meals. Lipid oxidation was significantly lower and carbohydrate oxidation was significantly higher after the HC meals than after the HF meals. Addition of red pepper to the experimental meals significantly increased diet-induced thermogenesis and lipid oxidation, particularly after the HF meal. On the other hand, carbohydrate oxidation was significantly decreased by the addition of red pepper to the experimental meals. Addition of red pepper to the HC meal increased the perceived oiliness of the meal to the same level as that of the HF meals. These results indicate that red pepper increases diet-induced thermogenesis and lipid oxidation. This increase in lipid oxidation is mainly observed when foods have a HF content whereas the increase in the perceived oiliness of the meal was found under the HC meal conditions.     

不同能量代谢水平对西安市中老年女性体质健康的影响

目的探讨西安市中老年女性不同剩余能量水平与体质健康的关系。方法2011年采用多阶段分层随机抽样的方法,抽取西安市40~60岁650名长住居民进行形态、机能、血生化、心理等指标进行测量;通过问卷调查其营养及体力活动状况,采用四分位数法对剩余能量(SE)进行水平分级,将受试对象分为以下4组:当SE相似文献   

Insulin sensitivity determines the effectiveness of dietary macronutrient composition on weight loss in obese women

OBJECTIVE: To determine whether macronutrient composition of a hypocaloric diet can enhance its effectiveness and whether insulin sensitivity (Si) affects the response to hypocaloric diets. RESEARCH METHODS AND PROCEDURES: Obese nondiabetic insulin-sensitive (fasting insulin < 10 microU/mL; n = 12) and obese nondiabetic insulin-resistant (fasting insulin > 15 microU/mL; n = 9) women (23 to 53 years old) were randomized to either a high carbohydrate (CHO) (HC)/low fat (LF) (60% CHO, 20% fat) or low CHO (LC)/high fat (HF) (40% CHO, 40% fat) hypocaloric diet. Primary outcome measures after a 16-week dietary intervention were: changes in body weight (BW), Si, resting metabolic rate, and fasting lipids. RESULTS: Insulin-sensitive women on the HC/LF diet lost 13.5 +/- 1.2% (p < 0.001) of their initial BW, whereas those on the LC/HF diet lost 6.8 +/- 1.2% (p < 0.001; p < 0.002 between the groups). In contrast, among the insulin-resistant women, those on the LC/HF diet lost 13.4 +/- 1.3% (p < 0.001) of their initial BW as compared with 8.5 +/- 1.4% (p < 0.001) lost by those on the HC/LF diet (p < 0.04 between two groups). These differences could not be explained by changes in resting metabolic rate, activity, or intake. Overall, changes in Si were associated with the degree of weight loss (r = -0.57, p < 0.05). DISCUSSION: The state of Si determines the effectiveness of macronutrient composition of hypocaloric diets in obese women. For maximal benefit, the macronutrient composition of a hypocaloric diet may need to be adjusted to correspond to the state of Si.     

Enteral versus parenteral nutrition: comparison of energy metabolism in lean and moderately obese women

Continuous respiratory-exchange measurements were performed on ten moderately obese and ten lean young women for 1 h before, 3 h during, and 3 h after either parenteral (IV) or intragastric (IG) administration of a nutrient mixture infused at twice the postabsorptive, resting energy expenditure (REE). REE rose significantly from 0.98 +/- 0.02 to 1.13 +/- 0.03 kcal/min (IV) and from 0.99 +/- 0.02 to 1.13 +/- 0.02 kcal/min (IG) in the lean group; from 1.10 +/- 0.02 to 1.27 +/- 0.03 kcal/min (IV) and from 1.11 +/- 0.02 to 1.29 +/- 0.03 (IG) in the obese group. These increases resulted in similar nutrient-induced thermogenesis of 10.0 +/- 0.7% (IV) and 9.3 +/- 0.9% (IG) in the lean group; of 9.2 +/- 0.7% (IV) and 10.1 +/- 0.8% (IG) in the obese. Nutrient utilization was comparable in both groups and in both routes of administration, although the response time to IG feeding was delayed. These results showed no significant difference in both the thermogenic response and nutrient utilization between moderately obese and control groups using acute IV or IG feeding.     

强化低热量肠外营养对重型颅脑损伤病人营养和免疫功能的影响

目的: 探讨丙氨酰谷氨酰胺双肽(Ala-Gln,丙谷双肽)强化的低热量PN支持对早期重型颅脑损伤病人免疫功能和营养代谢的影响. 方法: 将60例病人随机分为试验组和对照组,每组30例.试验组给予强化丙谷双肽的低热量PN支持;对照组给予标准的PN支持,共8 d.观察两组病人营养支持期间IgA、IgG、IgM、CD4、CD8、血糖、血清ALB、TF、Hb和氮平衡等. 结果: 试验组病人IgA、IgG、CD4和CD4/CD8比值均高于对照组(P<0.05,P<0.01).试验组病人营养支持第5和第8天后,血糖水平显著低于对照组(P<0.01). 结论: 丙谷双肽强化的低热量PN能增加早期重型颅脑损伤病人免疫功能,控制其应激性高血糖.     

Self-selected macronutrient diet affects energy and glucose metabolism in brown fat-ablated mice

OBJECTIVE: Obese transgenic UCP-DTA mice have largely ablated brown adipose tissue and develop obesity and diabetes, which are highly susceptible to a high-fat diet. We investigated macronutrient self-selection and its effect on development of obesity, diabetes, and energy homeostasis in UCP-DTA mice. RESEARCH METHODS AND PROCEDURES: UCP-DTA and wild-type littermates were fed a semisynthetic macronutrient choice diet (CD) ad libitum from weaning until 17 weeks. Energy homeostasis was assessed by measurement of food intake, food digestibility, body composition, and energy expenditure. Diabetes was assessed by blood glucose measurements and insulin tolerance test. RESULTS: Wild-type and UCP-DTA mice showed a high fat preference and increased energy digestion on CD compared with a low-fat standard diet. On CD, wild-type mice accumulated less body fat (16.9%) than UCP-DTA (32.6%) mice, although they had a higher overall energy intake. Compared with wild-type mice, resting metabolic rate was reduced in UCP-DTA mice irrespective of diet. UCP-DTA mice progressively decreased their carbohydrate intake, resulting in an almost complete avoidance of carbohydrate. UCP-DTA mice developed severe insulin resistance but showed decreased fed and fasted blood glucose on CD. DISCUSSION: In contrast to wild-type mice, UCP-DTA mice were not able to reduce their weight gain efficiency on CD. This suggests that, because of the high fat preference of the background strain and the increased metabolic efficiency, brown adipose tissue-deficient mice still develop obesity and insulin resistance on a macronutrient CD even when decreasing overall energy intake. Through the avoidance of carbohydrates, however, they are able to maintain normoglycemia.