Diet-induced thermogenesis measured over a whole day in obese and nonobese women.

The overall thermogenic response to food intake measured over a whole day in 20 young nondiabetic obese women (body fat mean +/- SEM: 38.6 +/- 0.7%), was compared with that obtained in eight nonobese control women (body fat: 24.7 +/- 0.9%). The energy expenditure of the subjects was continuously measured over 24 h with a respiration chamber, and the spontaneous activity was assessed by a radar system. A new approach was used to obtain the integrated thermogenic response to the three meals ingested over the day (from 8:30 AM to 10:30 PM). This method allows to subtract the energy expended for physical activity from total energy expenditure and to calculate the integrated dietary-induced thermogenesis as the difference between the energy expended without physical activity and basal metabolic rate. The thermogenic response to the three meals (expressed in percentage of the total energy ingested) was found to be blunted in obese women (8.7 +/- 0.8%) as compared with that of controls (14.8 +/- 1.1%). There was an inverse correlation between the percentage body fat and the diet-induced thermogenesis (r = -0.61, p less than 0.001). In addition, the relative increase in diurnal urinary norepinephrine excretion was lower in obese than in the control subjects. It is concluded that a low overall thermogenic response to feeding may be a contributing factor for energy storage in some obese subjects; a blunted response of the sympathetic nervous system could explain this low thermogenic response.

Resistance to diet-induced obesity and associated metabolic perturbations in haploinsufficient monocarboxylate transporter 1 mice

The monocarboxylate transporter 1 (MCT1 or SLC16A1) is a carrier of short-chain fatty acids, ketone bodies, and lactate in several tissues. Genetically modified C57BL/6J mice were produced by targeted disruption of the mct1 gene in order to understand the role of this transporter in energy homeostasis. Null mutation was embryonically lethal, but MCT1 (+/-) mice developed normally. However, when fed high fat diet (HFD), MCT1 (+/-) mice displayed resistance to development of diet-induced obesity (24.8% lower body weight after 16 weeks of HFD), as well as less insulin resistance and no hepatic steatosis as compared to littermate MCT1 (+/+) mice used as controls. Body composition analysis revealed that reduced weight gain in MCT1 (+/-) mice was due to decreased fat accumulation (50.0% less after 9 months of HFD) notably in liver and white adipose tissue. This phenotype was associated with reduced food intake under HFD (12.3% less over 10 weeks) and decreased intestinal energy absorption (9.6% higher stool energy content). Indirect calorimetry measurements showed ∼ 15% increase in O2 consumption and CO2 production during the resting phase, without any changes in physical activity. Determination of plasma concentrations for various metabolites and hormones did not reveal significant changes in lactate and ketone bodies levels between the two genotypes, but both insulin and leptin levels, which were elevated in MCT1 (+/+) mice when fed HFD, were reduced in MCT1 (+/-) mice under HFD. Interestingly, the enhancement in expression of several genes involved in lipid metabolism in the liver of MCT1 (+/+) mice under high fat diet was prevented in the liver of MCT1 (+/-) mice under the same diet, thus likely contributing to the observed phenotype. These findings uncover the critical role of MCT1 in the regulation of energy balance when animals are exposed to an obesogenic diet.

Stable isotope compositions of mammoth teeth from Niederweningen, Switzerland: Implications for the Late Pleistocene climate, environment, and diet

Oxygen and carbon isotope compositions of well-preserved mammoth teeth from the Middle Wurmian (40-70 ka) peat layer of Niederweningen, the most important mammoth site in Switzerland, were analysed to reconstruct Late Pleistocene palaeoclimatic and palaeoenvironmental conditions. Drinking water (delta(18)O values of approximately -12.3 +/- 0.9 parts per thousand were calculated front oxygen isotope compositions of mammoth tooth enamel apatite using a species-specific calibration for modern elephants. These delta(18)O(H2O) values reflect the mean oxygen isotope composition of the palaeo-precipitation and are similar to those directly measured for fate Pleistocene groundwater from aquifers in northern Switzerland and southern Germany. Using a present-day delta(18)O(H2)o-precipitation-air temperature relation for Switzerland, a mean annual air temperature (MAT) of around 4.3 +/- 2.1 degrees C can be calculated for the Middle Wurmian at this site. This MAT is in good agreement with palaeotemperature estimates on the basis of Middle Wurmian groundwater recharge temperatures and beetle assemblages. Hence, the climatic conditions in this region were around 4 degrees C cooler during the Middle Wurmian interstadial phase, around 45-50ka BP, than they are today. During this period the mammoths from Niederweningen lived in an open tundra-like, C(3) plant-dominated environment as indicated by enamel (delta(13)C values of -11.5 +/- 0.3 parts per thousand and pollen and macroplant fossils found in the embedding peat. The low variability of enamel delta(13)C and delta(18)O values from different mammoth teeth reflects similar environmental conditions and supports a relatively small time frame for the fossil assemblage. (C) 2006 Elsevier Ltd and INQUA. All rights reserved.

New approach for weight reduction by a combination of diet, light resistance exercise and the timing of ingesting a protein supplement.

We have reported that ingesting a meal immediately after exercise increased skeletal muscle accretion and less adipose tissue accumulation in rats employed in a 10 week resistance exercise program. We hypothesized that a possible increase in the resting metabolic rate (RMR) as a result of the larger skeletal muscle mass might be responsible for the less adipose deposition. Therefore, the effect of the timing of a protein supplement after resistance exercise on body composition and the RMR was investigated in 17 slightly overweight men. The subjects participated in a 12-week weight reduction program consisting of mild energy restriction (17% energy intake reduction) and a light resistance exercise using a pair of dumbbells (3-5 kg). The subjects were assigned to two groups. Group S ingested a protein supplement (10 g protein, 7 g carbohydrate, 3.3 g fat and one-third of recommended daily allowance (RDA) of vitamins and minerals) immediately after exercise. Group C did not ingest the supplement. Daily intake of both energy and protein was equal between the two groups and the protein intake met the RDA. After 12 weeks, the bodyweight, skinfold thickness, girth of waist and hip and percentage bodyfat significantly decreased in the both groups, however, no significant differences were observed between the groups. The fat-free mass significantly decreased in C, whereas its decrease in S was not significant. The RMR and post-meal total energy output significantly increased in S, while these variables did not change in C. In addition, the urinary nitrogen excretion tended to increase in C but not in S. These results suggest that the RMR increase observed in S might be associated with an increase in body protein synthesis.

Metabolic effects of a mixed and a high-carbohydrate low-fat diet in man, measured over 24 h in a respiration chamber.

1. The relation between dietary carbohydrate: lipid ratio and the fuel mixture oxidized during 24 h was investigated in eleven healthy volunteers (six females, and five males) in a respiration chamber. Values of the fuel mixture oxidized were estimated by continuous indirect calorimetry and urinary nitrogen measurements. 2. The subjects, were first given a mixed diet for 7 d and spent the last 24 h of the 7 d period in a respiration chamber for continuous gas-exchange measurement. The fuels oxidized during 2.5 h or moderate exercise were also measured in the respiration chamber. After an interval of 2 weeks from the end of the mixed-diet period, the same subjects were given an isoenergetic high-carbohydrate low-fat diet for 7 d, and the same experimental regimen was repeated. 3. Dietary composition markedly influenced the fuel mixture oxidized during 24 h and this effect was still present 12 h after the last meal in the postabsorptive state. However, the diets had no influence on the substrates oxidized above resting levels during exercise. With both diets, the 24 h energy balance was slightly negative and the energy deficit was covered by lipid oxidation. 4. With the high-carbohydrate low-fat diet, the energy expenditure during sleep was found to be higher than that with the mixed diet. 5. It is concluded that: (a) the composition of the diet did not influence the fuel mixture utilized for moderate exercise, (b) the energy deficit calculated for a 24 h period was compensated by lipid oxidation irrespective of the carbohydrate content of the diet, (c) energy expenditure during sleep was found to be higher with the high-carbohydrate low-fat diet than with the mixed diet.

Physical activity in free-living, overweight white and black women: divergent responses by race to diet-induced weight loss.

BACKGROUND: Black women are at greater risk of obesity than are white women, perhaps because of their lower levels of physical activity. OBJECTIVE: We compared free-living activity energy expenditure (AEE) in sedentary white and black women (in overweight and normal-weight states) and in never-overweight control subjects. DESIGN: Subjects included 46 women (23 white, 23 black) studied while overweight and after reaching a normal weight and 38 female control subjects (23 white, 15 black). Diet, without exercise training, resulted in a mean weight loss of 13 kg and a body mass index (in kg/m(2)) < 25. Body composition, sleeping energy expenditure, free-living total energy expenditure, and the energy cost of activity and aerobic capacity were assessed before and after weight loss under 4-wk, diet-controlled, weight-stable conditions and in the control subjects. AEE was defined as above-sleep energy expenditure. RESULTS: No significant racial differences in body composition, before or after weight loss, were found. After weight loss, AEE and aerobic capacity increased in the white women and decreased in the black women (P < 0.05 and P < 0.02, respectively). After weight loss, but not before, the white women had a significantly higher mean AEE than did the black women (2448 +/- 979 and 1728 +/- 1373 kJ/d, respectively; P < 0.05), approximating AEEs in the white (2314 +/- 1105) and black (2310 +/- 1251) control subjects. CONCLUSIONS: Relative to the responses of the white women to diet-induced weight loss, the black women became less fit and less physically active. Induction of a normal body weight in overweight black women appeared to produce a more obesity-prone state, favoring weight relapse.

Compliance to dietary advice directed towards increasing the carbohydrate to fat ratio of the everyday diet.

OBJECTIVE: To assess the effects, on food intake, body weight and body composition, of compliance to advice aiming at increasing the carbohydrate to fat ratio of the everyday diet without imposing voluntary restriction on the amount of food consumed. DESIGN: Eight moderately overweight women (body mass index > 27 kg/m2, relative body fat mass > 30%) received dietary advice during a 2 month period. Additionally, each evening the subjects had to consume a meal artificially enriched with 13C-glucose in order to assess their compliance from the 13CO2 enrichment in expired air. MEASUREMENTS: Dietary intakes, body weight, body composition and individual compliance. RESULTS: The energy derived from fat decreased from 44 +/- 1% to 31 +/- 1% and the proportion of carbohydrate increased from 38 +/- 2% to 50 +/- 1%, whereas the absolute carbohydrate intake remained constant (182 +/- 18 g/d). Energy intake decreased by 1569 +/- 520 kJ/d. There was a net loss of fat mass (1.7 +/- 0.7 kg, P = 0.016) with fat free mass maintenance. Dietary compliance ranged from 20 to 93% (mean: 60 +/- 8%) and was positively correlated to the loss of body fat mass. CONCLUSION: Advice aiming at increasing diet's carbohydrate to fat ratio induces a loss of fat mass with fat-free mass maintenance.

Stable carbon isotope Composition of c9,t11-conjugated linoleic acid in cow's milk as related to dietary fatty acids

This study explores the potential use of stable carbon isotope ratios (delta C-13) of single fatty acids (FA) as tracers for the transformation of FA from diet to milk, with focus on the metabolic origin of c9,t11-18:2. For this purpose, dairy cows were fed diets based exclusively on C-3 and C-4 plants. The FA in milk and feed were fractionated by silver-ion thin-layer chromatography and analyzed for their delta C-13 values. Mean delta C-13 values of FA from C-3 milk were lower compared to those from C-4 milk (-30.1aEuro degrees vs. -24.9aEuro degrees, respectively). In both groups the most negative delta C-13 values of all FA analyzed were measured for c9,t11-18:2 (C-3 milk = -37.0 +/- A 2.7aEuro degrees; C-4 milk -31.4 +/- A 1.4aEuro degrees). Compared to the dietary precursors 18:2n-6 and 18:3n-3, no significant C-13-depletion was measured in t11-18:1. This suggests that the delta C-13-change in c9,t11-18:2 did not originate from the microbial biohydrogenation in the rumen, but most probably from endogenous desaturation of t11-18:1. It appears that the natural delta C-13 differences in some dietary FA are at least partly preserved in milk FA. Therefore, carbon isotope analyses of individual FA could be useful for studying metabolic transformation processes in ruminants.

Dietary effects on muscle fatty acid composition of finished heifers

The effects of diet on Longissimus muscle fatty acid composition was determined using 24 crossbred heifers of Simmental vs. Nelore and Limousin vs. Nelore. The experimental diets were: 1) corn and yeast (CY); 2) corn, cottonseed meal + meat and bones meal (CMB); 3) cassava hull and yeast (CHY); 4) cassava hull, cottonseed meal + meat and bones meal (CHMB). Feeding CHMB diets resulted in lower lipid and higher cholesterol contents (P<0.05) for both crosses. Most of the identified fatty acids were monounsaturated, and the highest percentage was found to oleic acid (C18:1w9), with values ranging from 32.54 to 46.42%. Among the saturated fatty acids the palmitic acid (C16:0) showed the highest percentage, with its contents ranging between 19.40 and 32.44%. The highest polyunsaturated/saturated fatty acid ratio was of 0.30, and the lowest was of 0.08. Feeding CY diets resulted in lower cholesterol and higher polyunsaturated fatty acid contents of the Longissimus muscle.

Short-term, mixed-diet overfeeding in man: no evidence for "luxuskonsumption".

After 13 days of weight maintenance diet (13,720 +/- 620 kJ/day, 40% fat, 15% protein, and 45% carbohydrate), five young men (71.3 +/- 7.1 kg, 181 +/- 8 cm; means +/- SD) were overfed for 9 days at 1.6 times their maintenance requirements (i.e., +8,010 kJ/day). Twenty-four-hour energy expenditure (24-h EE) and basal metabolic rate (BMR) were measured on three occasions, once after 10 days on the weight-maintenance diet and after 2 and 9 days of overfeeding. Physical activity was monitored throughout the study, body composition was measured by underwater weighing, and nitrogen balance was assessed for 3 days during the two experimental periods. Overfeeding caused an increase in body weight averaging 3.2 kg of which 56% was fat as measured by underwater weighing. After 9 days of overfeeding, BMR increased by 622 kJ/day, which could explain one-third of the increase in 24-h EE (2,038 kJ/day); the remainder was due to the thermic effect of food (which increased in proportion with excess energy intake) and the increased cost of physical activity, related to body weight gain. This study shows that approximately one-quarter of the excess energy intake was dissipated through an increase in EE, with 75% being stored in the body. Under our experimental conditions of mixed overfeeding in which body composition measurements were combined with those of energy balance, it was possible to account for all of the energy ingested in excess of maintenance requirements.

Diet and gene interactions influence the skeletal response to polyunsaturated fatty acids.

Diets rich in omega-3s have been thought to prevent both obesity and osteoporosis. However, conflicting findings are reported, probably as a result of gene by nutritional interactions. Peroxisome proliferator-activated receptor-gamma (PPARγ) is a nuclear receptor that improves insulin sensitivity but causes weight gain and bone loss. Fish oil is a natural agonist for PPARγ and thus may exert its actions through the PPARγ pathway. We examined the role of PPARγ in body composition changes induced by a fish or safflower oil diet using two strains of C57BL/6J (B6); i.e. B6.C3H-6T (6T) congenic mice created by backcrossing a small locus on Chr 6 from C3H carrying 'gain of function' polymorphisms in the Pparγ gene onto a B6 background, and C57BL/6J mice. After 9months of feeding both diets to female mice, body weight, percent fat and leptin levels were less in mice fed the fish oil vs those fed safflower oil, independent of genotype. At the skeletal level, fish oil preserved vertebral bone mineral density (BMD) and microstructure in B6 but not in 6T mice. Moreover, fish oil consumption was associated with an increase in bone marrow adiposity and a decrease in BMD, cortical thickness, ultimate force and plastic energy in femur of the 6T but not the B6 mice. These effects paralleled an increase in adipogenic inflammatory and resorption markers in 6T but not B6. Thus, compared to safflower oil, fish oil (high ratio omega-3/-6) prevents weight gain, bone loss, and changes in trabecular microarchitecture in the spine with age. These beneficial effects are absent in mice with polymorphisms in the Pparγ gene (6T), supporting the tenet that the actions of n-3 fatty acids on bone microstructure are likely to be genotype dependent. Thus caution must be used in interpreting dietary intervention trials with skeletal endpoints in mice and in humans.

Cocoa flavonoid-enriched diet modulates systemic and intestinal immunoglobulin synthesis in adult Lewis rats

Previous studies have reported that a diet containing 10% cocoa, a rich source of flavonoids, has immunomodulatory effects on rats and, among others effects, is able to attenuate the immunoglobulin (Ig) synthesis in both systemic and intestinal compartments. The purpose of the present study was focused on investigating whether these effects were attributed exclusively to the flavonoid content or to other compounds present in cocoa. To this end, eight-week-old Lewis rats were fed, for two weeks, either a standard diet or three isoenergetic diets containing increasing proportions of cocoa flavonoids from different sources: one with 0.2% polyphenols from conventional defatted cocoa, and two others with 0.4% and 0.8% polyphenols, respectively, from non-fermented cocoa. Diet intake and body weight were monitored and fecal samples were obtained throughout the study to determine fecal pH, IgA, bacteria proportions, and IgA-coated bacteria. Moreover, IgG and IgM concentrations in serum samples collected during the study were quantified. At the end of the dietary intervention no clear changes of serum IgG or IgM concentrations were quantified, showing few effects of cocoa polyphenol diets at the systemic level. However, in the intestine, all cocoa polyphenol-enriched diets attenuated the age-related increase of both fecal IgA and IgA-coated bacteria, as well as the proportion of bacteria in feces. As these effects were not dependent on the dose of polyphenol present in the diets, other compounds and/or the precise polyphenol composition present in cocoa raw material used for the diets could be key factors in this effect.

Growth performance and body composition of giant trahira fingerlings fed diets with different protein and energy levels

The objective of this work was to determine the proper levels of protein and energy in diets of Hoplias lacerdae fingerlings. The dietary crude protein (CP) and gross energy (GE) levels for fingerlings of giant trahira were evaluated in a completely randomized 4x3 factorial design with 35, 39, 43 and 47% CP and 4,100, 4,300 and 4,500 kcal kg-1 of GE, and four replicates. The survival rate was 99.22%, and a linear improvement on the performance parameters was detected after increasing diet crude protein levels. Feed conversion ratio decreased with increasing levels of dietary protein and energy in the diets. A significant interaction between crude protein and gross energy was observed over body protein and mineral matter. Body lipid has increased linearly as gross energy in the diet increased. The retention of crude protein and energy showed a linear increasing with rising of crude protein levels in the diet. Crude protein level at 47% provides the best performance and energy retention, independently of the gross energy levels in the diet.

Chemical composition and fatty acid contents in farmed freshwater prawns

The objective of this work was to evaluate the chemical composition and fatty acid contents of Amazonian and giant river prawns. After four-month farming, with the same diet for both species, palmitic and stearic acids were the main saturated fatty acids. Oleic acid was the main monounsatured fatty acid, and the eicosapentaenoic and docosahexaenoic acids were the most abundant polyunsaturated acids. Amazonian prawn has higher levels of protein and polyunsaturated fatty acids than those of the giant river prawn, which shows its potential for aquaculture.