High-fat hypocaloric diet modifies carbohydrate utilization of obese rats during weight loss

The effects of fat content in the hypocaloric diet on whole body glucose oxidation and adipocyte glucose transport were investigated in two animal-feeding experiments. Diet-induced obese rats were food restricted to 75% of their previous energy intakes with either a high (45% by calorie) or a low (12% by calorie) corn oil diet for 9 wk (experiment 1) or 10 days (experiment 2). The losses of body weight (P < 0.05) and adipose depot weight (P < 0.05) were less in the 45% compared with the 12% fat group. During the dynamic phase of weight loss (day 10 of food restriction), plasma glucose and insulin concentrations were higher (P < 0.05) in the 45% than those in the 12% fat group. Whole body carbohydrate oxidation rate in response to an oral load of glucose was increased (P < 0.001) by food restriction in both dietary groups; however, carbohydrate oxidation rates were lower (P < 0.01) in the 45% than in the 12% fat-fed rats during the weight loss period. Adipocyte glucose transport was greater (P < 0.02) in the 45% than in the 12% fat group in an intra-abdominal adipose depot but not in subcutaneous fat. These data suggest that dietary fat content modifies whole body glucose oxidation and intra-abdominal adipocyte glucose uptake during weight loss.     

Short term effects of a low-carbohydrate diet in overweight and obese subjects with low HDL-C levels

Background

The aim of this study was to evaluate short-term effects of a low-carbohydrate diet in overweight and obese subjects with low HDL-C levels.

Methods

Overweight (BMI between 25-30 kg/m²) or obese (BMI over 30 kg/m²) subjects with low HDL-C levels (men with HDL-C <1.03, women <1.29 mmol/l) were invited to the study. A 1400 kcal 75-gram carbohydrate (CHO) diet was given to women and an 1800 kcal 100-gram CHO diet was given to men for four weeks. The distribution of daily energy of the prescribed diet was 21-22% from CHO, 26-29% from protein and 49-53% from fat. Subjects completed a three-day dietary intake record before each visit. Anthropometric indices, body fat ratio, blood lipids, glucose and insulin were measured. Baseline and week-four results were compared with a Wilcoxon signed ranks test.

Results

Twenty-five women and 18 men participated. Basal median LDL-C level of men was 3.11 and basal median LDL-C level of women was 3.00 mmol/l. After four weeks of a low-carbohydrate diet, the median energy intake decreased from 1901 to 1307 kcal/day, daily energy from carbohydrate from 55% to 33%, body weight from 87.7 to 83.0 kg and HDL-C increased from 0.83 to 0.96 mmol/l in men (p < 0.002, for all). After four weeks of a low-carbohydrate diet, the median energy intake tended to decrease (from 1463 to 1243 kcal, p = 0.052), daily energy from carbohydrate decreased from 53% to 30% (p < 0.001) and body weight decreased from 73.2 to 70.8 kg (p < 0.001) in women, but HDL-C did not significantly change (from 1.03 to 1.01 mmol/l, p = 0.165). There were significant decreases in body mass index, waist circumference, body fat ratio, systolic blood pressure, total cholesterol, triglyceride and insulin levels in all subjects.

Conclusions

HDL-C levels increased significantly with energy restriction, carbohydrate restriction and weight loss in men. HDL-C levels didn't change in women in whom there was no significant energy restriction but a significant carbohydrate restriction and a relatively small but significant weight loss. Our results suggest that both energy and carbohydrate restriction should be considered in overweight and obese subjects with low HDL-C levels, especially when LDL-C levels are not elevated.     

Leptin prevents obesity induced by a high-fat diet after diet-induced weight loss in the marsupial S. crassicaudata

The aims of this study were to determine in the marsupial Sminthopsis crassicaudata, the effects of leptin on food intake, body weight, tail width (a reflection of fat stores), and leptin mRNA, after caloric restriction followed by refeeding ad libitum with either a standard or high-fat preferred diet. S. crassicaudata (n = 32), were fed standard laboratory diet (LabD; 1.01 kcal/g, 20% fat) ad libitum fo 3 days. On days 4-10, animals received LabD at 75% of basal intake and then (days 11-25) were fed either LabD or a choice of LabD and mealworms (MW; 2.99 kcal/g, 30% fat); during this time, half the animals (n = 8) in each group received either leptin (2.5 mg/kg) or PBS intraperitoneally two times daily. On day 26, animals were killed and fat was removed for assay of leptin mRNA. At baseline, body weight, tail width, and food intake were similar in each group. After caloric restriction, body weight (P < 0.001) and tail width (P < 0.001) decreased. On return to ad libitum feeding in the PBS-treated animals, body weight and tail width returned to baseline in the LabD-fed animals (P < 0.001) and increased above baseline in the MW-fed animals (P < 0.001). In the LabD groups, tail width (P < 0.001) and body weight (P < 0.001) decreased after leptin compared with PBS. In the MW groups, the increase in tail width (P < 0.001) and body weight (P = 0.001) were attenuated after leptin compared with PBS. The expression of leptin mRNA in groups fed MW were greater in PBS than in leptin-treated animals (P < 0.05). Therefore, after diet-induced weight loss, leptin prevents a gain in fat mass in S. crassicaudata; this has potential implications for the therapeutic use of leptin.     

Are the Eating and Exercise Habits of Successful Weight Losers Changing?

Objective : The purpose of this study was to examine whether the diet and exercise behaviors of successful weight losers entering the National Weight Control Registry (NWCR) have changed between 1995 and 2003. Research Method and Procedures : Participants (N = 2708) were members of the NWCR who enrolled in intermittent years since 1995. Participants had lost an average of 33.1 kg and maintained a 13.6‐kg loss for 5.8 years before enrollment. Evaluations of diet and physical activity were conducted at entry into the NWCR and prospectively over 1 year. Results : From 1995 to 2003, the daily percentage of calories from fat increased from 23.8% to 29.4%, saturated fat intake increased from 12.3 to 154.0 g/d, and calories from carbohydrate decreased from 56.0% to 49.3% (p < 0.0001). The proportion consuming <90 grams of carbohydrate (considered a low‐carbohydrate diet) increased from 5.9% to 17.1% (p = 0.0001). Physical activity was elevated in 1995 (mean = 3316 kcal/wk) but comparable in all other years (mean = 2620 kcal/wk). Stepwise regression collapsing across cohorts indicated that weight regain over 1 year was related to higher levels of caloric intake, fast food consumption, and fat intake and lower levels of physical activity (p < 0.03). Discussion : The macronutrient composition of the diet of NWCR members has shifted over the past decade. Still, only a minority consumes a low‐carbohydrate diet. Despite changes in the diet over time, the variables associated with long‐term maintenance of weight loss were the same: continued consumption of a low‐calorie diet with moderate fat intake, limited fast food, and high levels of physical activity.     

Effects of a hypocaloric,low-carbohydrate diet on weight loss,blood lipids,blood pressure,glucose tolerance,and body composition in free-living overweight women

The purpose of the current study was to examine the effects of a very low-carbohydrate diet on weight loss and biochemical parameters in overweight women. Twenty women completed an 8-week trial that reduced their daily carbohydrate intake from 232 to 71 g (p < 0.05) and reduced energy by 2,644 kJ/day (8,384 to 5,740 kJ, p < 0.001). The average weight loss was 5.0 kg (p < 0.0001), with a net decrease in body mass index of 1.82 kg/m2, a loss of 3.4% body fat (4 kg, p < 0.0001), and a loss of 1.0 kg lean mass (p < 0.05). There were no significant changes in fasting blood glucose, fasting serum insulin, oral glucose tolerance, free or total insulin-like growth factor-1, or total IGFBP-3. Systolicblood pressure decreased by an average of 9.0 mmHg (1 mmHg = 133.322 Pa) (p < 0.01) and diastolic blood pressure decreased by 7 mmHg (p < 0.05). Total cholesterol decreased 1.2 mM (p < 0.001), all of which was accounted for by a decrease in low-density lipoprotein cholesterol (p < 0.001) with no change in high-density lipoprotein cholesterol (baseline, 1.17 mM; week 8, 1.22 mM). Total triacylglycerol decreased 0.6 mM (p < 0.01), and the ratio of triacylglycerol/HDL also significantly decreased (baseline, 1.40; week 8, 0.87; p < 0.001). Serum beta-hydroxybutyrate concentrations rose significantly by week 2 and declined thereafter but remained significantly higher than baseline values for the duration of the intervention. Therefore, carbohydrate restriction to 70 g or less with concomitant energy restriction, without changes in protein or fat consumption, promotes weight loss, and improvements in body composition, blood pressure, and blood lipids without compromising glucose tolerance in moderately overweight women.     

Appetite at "high altitude" [Operation Everest III (Comex-'97)]: a simulated ascent of Mount Everest.

We hypothesized that progressive loss of body mass during high-altitude sojourns is largely caused by decreased food intake, possibly due to hypobaric hypoxia. Therefore we assessed the effect of long-term hypobaric hypoxia per se on appetite in eight men who were exposed to a 31-day simulated stay at several altitudes up to the peak of Mt. Everest (8,848 m). Palatable food was provided ad libitum, and stresses such as cold exposure and exercise were avoided. At each altitude, body mass, energy, and macronutrient intake were measured; attitude toward eating and appetite profiles during and between meals were assessed by using questionnaires. Body mass reduction of an average of 5 +/- 2 kg was mainly due to a reduction in energy intake of 4.2 +/- 2 MJ/day (P < 0.01). At 5,000- and 6,000-m altitudes, subjects had hardly any acute mountain sickness symptoms and meal size reductions (P < 0.01) were related to a more rapid increase in satiety (P < 0.01). Meal frequency was increased from 4 +/- 1 to 7 +/- 1 eating occasions per day (P < 0. 01). At 7,000 m, when acute mountain sickness symptoms were present, uncoupling between hunger and desire to eat occurred and prevented a food intake necessary to meet energy balance requirements. On recovery, body mass was restored up to 63% after 4 days; this suggests physiological fluid retention with the return to sea level. We conclude that exposure to hypobaric hypoxia per se appears to be associated with a change in the attitude toward eating and with a decreased appetite and food intake.     

Amount of Food Group Variety Consumed in the Diet and Long‐Term Weight Loss Maintenance

Objective: Decreases in variety of foods consumed within high‐fat‐dense food groups and increases in variety of foods consumed within low‐fat‐dense food groups are associated with lower energy intake and greater weight loss during obesity treatment and may assist with weight loss maintenance. This study examined food group variety in 2237 weight loss maintainers in the National Weight Control Registry, who had lost 32.2 ± 18.0 kg (70.9 ± 39.5 lbs) and maintained a weight loss of at least 13.6 kg (30 lbs) for 6.1 ± 7.7 years. Research Methods and Procedures: At entry into the registry, registry members completed a food frequency questionnaire from which amount of variety consumed from different food groups was assessed. To provide a context for interpreting the level of variety occurring in the diet of registry participants, food group variety was compared between registry participants and 96 individuals who had recently participated in a behavioral weight loss program and had lost at least 7% of initial body weight. Results: Registry members reported consuming a diet with very low variety in all food groups, especially in those food groups higher in fat density. Registry participants consumed significantly (p < 0.001) less variety within all food groups, except fruit and combination foods, than recent weight losers after 6 months of weight loss treatment. Discussion: These results suggest that successful weight loss maintainers consume a diet with limited variety in all food groups. Restricting variety within all food groups may help with consuming a low‐energy diet and maintaining long‐term weight loss.     

Influence of a diet rich in fish oil on blood pressure, body weight and cardiac hypertrophy in spontaneously hypertensive rats

The effects of a diet rich in fish oil on arterial blood pressure, body weight, left ventricular weight and heart rate have been investigated in 8 month old spontaneously hypertensive male rats (SHR) as compared to age-matched hypertensive controls. A diet containing 10% fish oil decreased blood pressure by about 40 mmHg within 20 days of starting the experiment, and this effect persisted over the observation period of 80 days. Permitting the animals free access to food, the body weight of the diet group increased by 25%. The degree of hypertrophy as evaluated by relating left ventricular weight to tibial length was significantly reduced (10%) in the diet fed group. Heart rate was increased by 53%. The study demonstrates that a diet rich in fish oil can lower arterial blood pressure over several weeks without a recognizable loss in function despite a considerable increase in body weight. It can be assumed that a more marked regression of left ventricular hypertrophy is counteracted by a reflex increase in sympathetic efferentation to the heart.     

Randomised comparison of diets for maintaining obese subjects' weight after major weight loss: ad lib,low fat,high carbohydrate diet v fixed energy intake.

OBJECTIVES: To compare importance of rate of initial weight loss for long term outcome in obese patients and to compare efficacy of two different weight maintenance programmes. DESIGN: Subjects were randomised to either rapid or slow initial weight loss. Completing patients were re-randomised to one year weight maintenance programme of ad lib diet or fixed energy intake diet. Patients were followed up one year later. SETTING: University research department in Copenhagen, Denmark. SUBJECTS: 43 (41 women) obese adults (body mass index 27-40) who were otherwise healthy living in or around Copenhagen. INTERVENTIONS: 8 weeks of low energy diet (2 MJ/day) or 17 weeks of conventional diet (5 MJ/day), both supported by an anorectic compound (ephedrine 20 mg and caffeine 200 mg thrice daily); one year weight maintenance programme of ad lib, low fat, high carbohydrate diet or fixed energy intake diet (< or = 7.8 MJ/day), both with reinforcement sessions 2-3 times monthly. MAIN OUTCOME MEASURES: Mean initial weight loss and proportion of patients maintaining a weight loss of > 5 kg at follow up. RESULTS: Mean initial weight loss was 12.6 kg (95% confidence interval 10.9 to 14.3 kg) in rapid weight loss group and 12.6 (9.9 to 15.3) kg in conventional diet group. Rate of initial weight loss had no effect on weight maintenance after 6 or 12 months of weight maintenance or at follow up. After weight maintenance programme, the ad lib group had maintained 13.2 (8.1 to 18.3) kg of the initial weight loss of 13.5 (11.4 to 15.5) kg, and the fixed energy intake group had maintained 9.7 (6.1 to 13.3) kg of the initial 13.8 (11.8 to 15.7) kg weight loss (group difference 3.5 (-2.4 to 9.3) kg). Regained weight at follow up was greater in fixed energy intake group than in ad lib group (11.3 (7.1 to 15.5) kg v 5.4 (2.3 to 8.6) kg, group difference 5.9 (0.7 to 11.1) kg, P < 0.03). At follow up, 65% of ad lib group and 40% of fixed energy intake group had maintained a weight loss of > 5 kg (P < 0.07). CONCLUSION: Ad lib, low fat, high carbohydrate diet was superior to fixed energy intake for maintaining weight after a major weight loss. The rate of the initial weight loss did not influence long term outcome.     

Adiponectin changes in relation to the macronutrient composition of a weight-loss diet

Adiponectin is an adipose-derived protein with beneficial metabolic effects. Low adiponectin is associated with obesity and related diseases. Significant weight loss increases adiponectin, reducing disease risk. This study compared the effects of two weight-loss diets with different macronutrient compositions on adiponectin. Eighty-one obese women in two cohorts were randomized to a low-fat (LF) or a low-carbohydrate (LC) diet. All subjects underwent equivalent weight-loss intervention, with weight and other measures assessed at baseline and after 6 (cohort I) or 4 (cohort II) months. Body fat was measured by dual energy X-ray absorptiometry. Adiponectin was measured by radioimmunoassay. Diet intake was assessed using 24-h recalls and 3-day diet records. Data were analyzed via t-tests and repeated-measures factorial ANOVA using time, diet, and replicate (cohort I vs. cohort II) as factors. Age, weight, body fat, BMI, adiponectin, and diet were similar at baseline. Following intervention, macronutrient composition of the diet was vastly different between the groups, reflecting the assigned diet. Both groups lost weight and body fat (P < 0.001), with effect in LC dieters greater than LF dieters (-9.1 kg vs. -4.97 kg weight, P < 0.05 and -5.45 kg vs. -2.62 kg fat, P < 0.001). Adiponectin increased in the LC (+1.92 mcg/ml, P < 0.01), but not the LF (+0.86 mcg/ml, P = 0.81), group. There was no correlation between weight loss and increase in adiponectin. These results confirm that diet-induced loss of weight and body fat is associated with increased adiponectin concentrations. This effect is evident with weight loss of 10% or more, and may be greater with LC diets.     

Huperzine A Ameliorates Cognitive Deficits and Oxidative Stress in the Hippocampus of Rats Exposed to Acute Hypobaric Hypoxia

Acute exposure to high altitudes can cause neurological dysfunction due to decreased oxygen availability to the brain. In this study, the protective effects of Huperzine A on cognitive deficits along with oxidative and apoptotic damage, due to acute hypobaric hypoxia, were investigated in male Sprague–Dawley rats. Rats were exposed to simulated hypobaric hypoxia at 6,000 m in a specially fabricated animal decompression chamber while receiving daily Huperzine A orally at the dose of 0.05 or 0.1 mg/kg body weight. After exposure to hypobaric hypoxia for 5 days, rats were trained in a Morris Water Maze for 5 consecutive days. Subsequent trials revealed Huperzine A supplementation at a dose of 0.1 mg/kg body weight restored spatial memory significantly, as evident from decreased escape latency and path length to reach the hidden platform, and the increase in number of times of crossing the former platform location and time spent in the former platform quadrant. In addition, after exposure to hypobaric hypoxia, animals were sacrificed and biomarkers of oxidative damage, such as reactive oxygen species, lipid peroxidation, lactate dehydrogenase activity, reduced glutathione, oxidized glutathione and superoxide dismutase were studied in the hippocampus. Expression levels of pro-apoptotic proteins (Bax, caspase-3) and anti-apoptotic protein (Bcl-2) of hippocampal tissues were evaluated by Western blotting. There was a significant increase in oxidative stress along with increased expression of apoptotic proteins in hypoxia exposed rats, which was significantly improved by oral Huperzine A at 0.1 mg/kg body weight. These results suggest that supplementation with Huperzine A improves cognitive deficits, reduces oxidative stress and inhibits the apoptotic cascade induced by acute hypobaric hypoxia.     

Pharmacological actions of the peptide hormone amylin in the long-term regulation of food intake, food preference, and body weight

The ability of amylin to reduce acute food intake in rodents is well established. Longer-term administration in rats (up to 24 days) shows a concomitant reduction in body weight, suggesting energy intake plays a significant role in mediating amylin-induced weight loss. The current set of experiments further explores the long-term effects of amylin (4-11 wk) on food preference, energy expenditure, and body weight and composition. Furthermore, we describe the acute effect of amylin on locomotor activity and kaolin consumption to test for possible nonhomeostatic mechanisms that could affect food intake. Four-week subcutaneous amylin infusion of high-fat fed rats (3-300 microg.kg(-1).day(-1)) dose dependently reduced food intake and body weight gain (ED(50) for body weight gain = 16.5 microg.kg(-1).day(-1)). The effect of amylin on body weight gain was durable for up to 11 wks and was associated with a specific loss of fat mass and increased metabolic rate. The body weight of rats withdrawn from amylin (100 microg.kg(-1).day(-1)) after 4 wks of infusion returned to control levels 2 wks after treatment cessation, but did not rebound above control levels. When self-selecting calories from a low- or high-fat diet during 11 wks of infusion, amylin-treated rats (300 microg.kg(-1).day(-1)) consistently chose a larger percentage of calories from the low-fat diet vs. controls. Amylin acutely had no effect on locomotor activity or kaolin consumption at doses that decreased food intake. These results demonstrate pharmacological actions of amylin in long-term body weight regulation in part through appetitive-related mechanisms and possibly via changes in food preference and energy expenditure.     

Effects of maternal leptin treatment during lactation on the body weight and leptin resistance of adult offspring

We investigate whether leptin treatment to lactating rats affects food intake, body weight and leptin serum concentration and its anorectic effect on their adult offspring. Lactating rats were divided into 2 groups: Lep-single injected with recombinant rat leptin (8 microg/100 g of body weight, daily for the last 3 consecutive days of lactation) and control group (C) that received the same volume of saline. After weaning all pups had free access to the control diet, their body weight and food intake were monitored at each 4 days until 180 days of age, when they were tested for its food intake and response to either leptin (0.5 mg/kg body wt, ip) or saline vehicle. The offspring of the leptin-treated dams gained more weight and had higher food intake from day 37 onward (p<0.05), higher amount of retroperitoneal white adipose tissue (RPWAT) (37%, p<0.05) and higher leptin serum concentration (40%, p<0.05) at 180 days of age compared to control group. The food intake at 2, 4, 6 and 24 h was unaffected after acute injection of leptin in these animals, suggesting resistance to the anorectic effect of leptin. The maternal leptin treatment during lactation makes their adult offspring more susceptible to overweight with resistance to the anorectic effect of leptin.     

Ultrastructural morphometry of matrical changes induced by exercise and food restriction in the rat calcaneal tendon.

The ultrastructural morphometry of collagen fibril populations in 24 calcaneal tendons obtained from 12 Fischer 344 rats were studied to elucidate matrical changes induced by food restriction and/or endurance exercise. Rats were randomly assigned to four equal groups: ad libitum control (AC), ad libitum exercise (AE), restricted diet control (RC) and restricted diet exercise (RE) groups. Beginning from 6 weeks of age, animals in the two food restriction groups were fed 60% of the mean food consumption of ad libitum fed rats. Then, starting from 6-7 months of age, the rats in the two exercise groups performed 40-50 min of treadmill running at 1.2-1.6 miles h-1 every day for a total of 10 weeks. Endurance training did not significantly alter body weight, but food restriction with or without exercise resulted in a significant loss of body weight. In ad libitum fed controls, food restriction alone did not significantly alter the mean collagen fibril CSA, but predisposed a preponderance of small-sized collagen fibrils. Endurance training per se induced a significant (32%) increase in mean fibril CSA (P less than 0.05), but this adaptive response to exercise was prevented by food restriction, as indicated by a 33% decline in fibril CSA (P less than 0.05). These findings demonstrate that dietary restriction modifies the adaptation of tendon collagen morphometry in response to endurance training, and that weight loss is better achieved with food restriction than endurance exercise.     

Oleoyl-estrone induces the massive loss of body weight in Zucker fa/fa rats fed a high-energy hyperlipidic diet

To test whether oleoyl-estrone plus a hyperlipidic diet affects body weight in Zucker fa/fa rats, 13-week-old male Zucker obese (fa/fa) rats initially weighing 440-470 g were used. They were fed for 15 days with a powdered hyperlipidic diet (16.97 MJ/kg metabolizable energy) in which 46.6% was lipid-derived and 16.1% was protein-derived energy and containing 1.23 +/- 0.39 μmol/kg of fatty-acyl esters of estrone. This diet was supplemented with added oleoyl-estrone to produce a diet with 33.3 μmol/kg of fatty-acyl estrone. Oral administration of oleoyl-estrone in a hyperlipidic diet (at a mean dose of 0.5 μmol. kg(-1).d(-1)) resulted in significant losses of fat, energy and, ultimately, weight. Treatment induced the maintenance of energy expenditure combined with lower food intake, creating an energy gap that was filled with internal fat stores while preserving body protein, in contrast with the marked growth of controls fed the hyperlipidic diet. Treatment of genetically obese rats with a hyperlipidic diet containing additional oleoyl-estrone resulted in the loss of fat reserves with scant modification of other metabolic parameters, except for lower plasma glucose and insulin levels. The results agree with the postulated role of oleoyl-estrone as a ponderostat signal.     

Effects of excess biotin administration on the growth and urinary excretion of water-soluble vitamins in young rats

To determine the effects of excess biotin administration on growth and water-soluble vitamin metabolism, weaning rats were fed on a 20% casein diet containing 0.00002% biotin, or same diet with 0.04, 0.08, 0.10, 0.20, 0.50, 0.80 or 1.0% added biotin for 28 days. More than 0.08% biotin administration decreased the food intake and body weight gain compared with the levels in control rats. An accumulation of biotin in such tissues as the liver, brain and kidney increased in a dose-dependent manner, and the both bound and free biotin contents in the liver also increased in a dose-dependent manner. An excess administration of biotin did not affect the urinary excretion of other water-soluble vitamins, suggesting no effect on the metabolism of other water-soluble vitamins. The results of the food intake and body weight gain indicated that the lowest observed adverse effect level for young rats was 79.2 mg/kg body weight/day, while the no observed adverse effect level was 38.4 mg/kg/day. These results suggested immediately setting a tolerable upper intake level for biotin.     

Endogenous N-excretion and minimal protein requirement for maintenance of the common marmoset (Callithrix jacchus)

The protein requirement for maintenance of the marmoset Callithrix jacchus was investigated by factorial calculation via the N balance technique. Six adult male marmosets were fed a protein-free pelleted diet for 22 days. When a low protein diet (6%) was fed in the preperiod, only 7 days were necessary and when fed a higher protein diet (18%) 10 days were necessary to reach a minimum of N excretion during protein depletion. Body weight losses averaged 11% and food intake was 21% lower in the protein free period. The average endogenous urine N (EUN) was 62.1 mg N and endogenous fecal N (EFN) 49.2 mg N/kg W0.75. Body surface losses (BSN) were assumed to be 20 mg N/kg W0.75. The total endogenous loss of 131.3 mg N/kg W0.75 is similar to that of other species. Net protein utilization (NPU) of well balanced proteins, determined near the N equilibrium, was 51.8%. The calculated net protein requirement amounts to 313.6 mg N/kg W0.75, which corresponds to a dietary protein content of 6% in a diet of high caloric density, (about 19-20 MJ/kg dry matter) when the food intake is 3.3% of body weight.     

Biochemical and immunological changes on oral glutamate feeding in male albino rats

 High altitude stress leads to lipid peroxidation and free radical formation which results in cell membrane damage in organs and tissues, and associated mountain diseases. This paper discusses the changes in biochemical parameters and antibody response on feeding glutamate to male albino Sprague Dawley rats under hypoxic stress. Exposure of rats to simulated hypoxia at 7576 m, for 6 h daily for 5 consecutive days, in an animal decompression chamber at 32±2° C resulted in an increase in plasma malondialdehyde level with a concomitant decrease in blood glutathione (reduced) level. Supplementation of glutamate orally at an optimal dose (27 mg/kg body weight) in male albino rats under hypoxia enhanced glutathione level and decreased malondialdehyde concentration significantly. Glutamate feeding improved total plasma protein and glucose levels under hypoxia. The activities of serum glutamate oxaloacetate transaminase (SGOT) and serum glutamate pyruvate transaminase (SGPT) and the urea level remained elevated on glutamate supplementation under hypoxia. Glutamate supplementation increased the humoral response against sheep red blood cells (antibody titre). These results indicate a possible utility of glutamate in the amelioration of hypoxia-induced oxidative stress. Received: 23 March 1998 / Accepted: 19 October 1998     

Profiling of Energy Metabolism in Olanzapine‐Induced Weight Gain in Rats and Its Prevention by the CB1‐Antagonist AVE1625

This is the first study to examine the effect of subchronic olanzapine (OLZ) on energy homeostasis in rats, covering all aspects of energy balance, including energy intake as metabolizable energy, storage, and expenditure. We further analyzed whether, and by which mechanism, the CB1‐antagonist AVE1625 might attenuate OLZ‐induced body weight gain. For this purpose, we selected juvenile female Hanover Wistar rats that robustly and reproducibly demonstrated weight gain on OLZ treatment, accepting limitations to model the aberrations on lipid and carbohydrate metabolism. Rats received 2 mg/kg OLZ orally twice daily for 12 days. Body weight and body composition were analyzed. Moreover daily food intake, energy expenditure, and substrate oxidation were determined in parallel to motility and body core temperature. OLZ treatment resulted in substantial body weight gain, in which lean and fat mass increased significantly. OLZ‐treated rats showed hyperphagia that manifested in increased carbohydrate oxidation and lowered fat oxidation (FO). Energy expenditure was increased, motility decreased, but there was no indication for hypothermia in OLZ‐treated rats. Coadministration of OLZ and AVE1625 (10 mg/kg orally once daily) attenuated body weight gain, diminishing the enhanced food intake while maintaining increased energy expenditure and decreased motility. Our data reveal that energy expenditure was enhanced in OLZ‐treated rats, an effect not critically influenced by motility. Energy uptake, however, exceeded energy expenditure and led to a positive energy balance, confirming hyperphagia as the major driving factor for OLZ‐induced weight gain. Combination of OLZ treatment with the CB1‐antagonist AVE1625 attenuated body weight gain in rats.     

Weight Loss During 12 Weeks' Ad Libitum Carbohydrate-Rich Diet in Overweight and Normal-Weight Subjects at a Danish Work Site

The effect of 12 weeks' ad libitum carbohydrate-rich, low-fat diet on total body weight, lean body mass, and fat mass was studied in a group of healthy subjects at a Danish work-site (I) (n=50, BMI = 28.4 ± 0.7 kg/m²). Sixteen subjects served as controls (C) (BMI = 27.0 ± 1.0 kg/m²). After 12 weeks the I subjects had decreased their fat intake from 39.0 ± 1.1 energy-% (E%) to 28.0 ± 1.2 E% and increased their carbohydrate intake from 46.0 ± 1.1 E% to 56.4 ± 1.1 E% (p < 0.05 vs. C). Moreover, a significant loss of body weight (4.2 ± 0.4 kg) and fat mass (4.4 ± 0.6 kg) was observed in I (p < 0.05 vs. C). The weight loss in I was not regained at 24 and 52 weeks' follow-up (82% of I participating) compared to baseline. The cost per kg lost weight amounted to $14.7/person. In conclusion, instructions at a work site in ad libitum intake of a carbohydrate-rich, low-fat diet resulted in a significant loss of body weight and fat mass in overweight and normal-weight subjects.