Effect of postweaning feeding on the performance and energy balance of female rabbits at different physiological states.
The feeding of a high-fiber and low-energy diet to young rabbit does from weaning to the first kindling was used to modify their body reserves, stimulate their energy intake, and reduce the energy deficit during the first lactation. Rabbits (53 per group) were given ad libitum access to either a control or high-fiber diet (CP, 17.6 vs 15.8% of DM; crude fiber, 15.5 vs 19.9% of DM; digestible energy, 2,565 vs 2,261 kcal/kg of DM, respectively) from weaning to their first kindling. During lactation, both groups received the same diet, which contained 19.3% CP, 16.5% crude fiber, and 2,634 kcal/kg digestible energy (dry matter basis). Four comparative slaughters were performed to estimate the chemical and energy balance of rabbit does at different physiological states: at the beginning of the trial (12 rabbits, 45 d of age), at mating (10 rabbits per group, 136 d), at kindling (10 rabbits per group, 167 d), and at the end of lactation (12 and 11 rabbits for the control and the high-fiber group, 197 d). Large changes in body weight and composition were observed between slaughters. From 45 d to mating, doe body fat and energy increased 7.93 and 4.64 times the initial content, respectively. During pregnancy, body protein concentration decreased from 203 to 186 g/kg. At the end of lactation, body fat and energy concentration were reduced to values close to those measured at 45 d of age. Dietary treatment affected body chemical and energy balance during pregnancy and lactation but not reproductive and lactational performance. The high-fiber diet stimulated feed intake from weaning to the first kindling but not dietary energy intake. During lactation, the rabbits fed the high-fiber diet ate 10 kcal x d(-1) x kg live weight(-.75) more and lost less body fat (-405 vs -504 g) and body energy (-3,628 vs -4,294 kcal) than the does fed the control diet (P < .001). In the same period, all does showed water and protein retention (185 and 45 g, on average) regardless of dietary treatment. In conclusion, feeding young does a high-fiber diet until their first kindling reduced the chemical and energy body deficit at the end of the first lactation. (+info)
Use of the leg-to-leg bioelectrical impedance method in assessing body-composition change in obese women.
BACKGROUND: There is little information on whether bioelectrical impedance analysis (BIA) accurately predicts changes in body composition associated with energy restriction, exercise, or both. OBJECTIVE: We had 2 objectives: to determine the validity of the leg-to-leg BIA system in 1) estimating body composition in obese and nonobese women, with a cross-sectional design, and 2) assessing changes in body composition in obese women in response to 12 wk of energy restriction, exercise training, or both. DESIGN: Subjects were 98 moderately obese women (43.2 +/- 0.6% body fat, 45.0 +/- 1.1 y of age) and 27 nonobese control subjects (24.0 +/- 1.5% body fat, 43.5 +/- 2.5 y of age). Obese subjects were randomly divided into 1 of 4 groups, with fat-free mass, fat mass, and percentage body fat estimated with BIA and underwater weighing before and after 12 wk of intervention. The 4 groups were diet only (4.19-5.44 MJ/d), exercise only (five, 45-min sessions/wk at 78.5 +/- 0.5% of maximum heart rate), both exercise and diet, and control (no diet or exercise). RESULTS: No significant difference was found between underwater weighing and BIA in estimating the fat-free mass of the obese and nonobese women (all subjects combined, r = 0.78, P < 0.001, SEE = 3.7 kg) or in estimating decreases in fat mass during 12 wk of energy restriction, exercise, or both in obese subjects (F[3.85] = 1.45, P = 0.233). CONCLUSIONS: The leg-to-leg BIA system accurately assessed fat-free mass in obese and nonobese women, and changes in fat mass with diet alone or when combined with exercise. (+info)
Effect of calorie restriction on in vivo glucose metabolism by individual tissues in rats.
We evaluated the effects of 8 mo of calorie restriction [CR: 60% of ad libitum (AL) food intake] on glucose uptake by 14 tissues in unanesthetized, adult (12 mo) F344xBN rats. Glucose metabolism was assessed by the 2-[3H]deoxyglucose tracer technique at 1500 or 2100. Despite an approximately 60% decline in insulinemia with CR, plasma 2-[3H]deoxyglucose clearance for CR was greater than for AL at both times. A small, CR-related decrease in glucose metabolic index (R'g) occurred only at 1500 in the spleen and heart, and this decrease was reversed at 2100. In some tissues (cerebellum, lung, kidney, soleus, and diaphragm), R'g was unaffected by diet, regardless of time. In the other tissues (brown fat, 3 white fat pads, epitrochlearis, plantaris, and gastrocnemius), R'g was higher or tended to be higher for CR vs. AL at one or both times. These findings indicate that 8 mo of CR did not cause a continuous reduction in in vivo glucose uptake by any tissue studied, and, in several insulin-sensitive tissues, glucose uptake was at times greater for CR vs. AL rats. (+info)
Effect of long-term caloric restriction and exercise on muscle bioenergetics and force development in rats.
We evaluated the hypothesis that long-term caloric restriction and exercise would have beneficial effects on muscle bioenergetics and performance in the rat. By themselves, each of these interventions is known to increase longevity, and bioenergetic improvements are thought to be important in this phenomenon. Accordingly, we investigated rats that underwent long-term caloric restriction and were sedentary, ad libitum-fed rats permitted to exercise by daily spontaneous wheel running (AE), and the combination of the dietary and exercise interventions (RE). Ad libitum-fed, sedentary rats comprised the control group. 31P NMR spectra of the gastrocnemius muscle (GM) were collected in vivo at rest and during two periods of electrical stimulation. Neither caloric restriction nor exercise affected the ratio of phosphocreatine to ATP or pH at rest. During the first stimulation and after recovery, the RE group had a significantly smaller decline in pH than did the other groups (P < 0.05). During the second period of stimulation, the decrease in pH was much smaller in all groups than during the first stimulation, with no differences observed among the groups. The combination of caloric restriction and exercise resulted in a significant attenuation in the decline in developed force during the second period of stimulation (P < 0.05). A biochemical correlate of this was a significantly higher concentration of citrate synthase in the GM samples from the RE rats (32.7 +/- 5.4 micromol. min-1. g-1) compared with the AE rats (17.6 +/- 5.7 micromol. min-1. g-1; P < 0.05). Our experiments thus demonstrated a synergistic effect of long-term caloric restriction and free exercise on muscle bioenergetics during electrical stimulation. (+info)
Effects of aerobic or resistance exercise and/or diet on glucose tolerance and plasma insulin levels in obese men.
OBJECTIVE: This study had two objectives. First, we examined whether the influence of diet combined with either aerobic (DA) (n = 10) or resistance (DR) (n = 10) exercise has effects on insulin and glucose levels that are different in obese men. Second, we tried to determine whether the combination of diet and exercise is associated with improvements in insulin and glucose levels that are greater than those associated with diet alone (DO) (n = 9). RESEARCH DESIGN AND METHODS: Insulin and glucose levels were measured after an overnight fast and a 75-g oral glucose challenge (OGTT). Visceral adipose tissue (AT), subcutaneous AT, and skeletal muscle were measured by magnetic resonance imaging (MRI) before and after treatment (16 weeks). RESULTS: Reductions in weight (12.4 +/- 3.8 kg) and in visceral (37 +/- 15.1%) and subcutaneous AT (24.3 +/- 8.6%) were not different between treatments (P > 0.05). Skeletal muscle was maintained in the DA and DR groups but was reduced (7.3 +/- 2.8%) in the DO group (P < 0.05). Independent of treatment, fasting glucose and OGTT glucose did not change (P > 0.05). However, fasting insulin, OGTT insulin, and the insulin-to-glucose ratio decreased within all treatments (P < 0.05). Reductions in the OGTT insulin area under the curve were greater (P < 0.05) within the DA (52 +/- 12%) and DR (42 +/- 17%) treatments than in the DO (20 +/- 15%) treatment. Collapsed across group, reductions in visceral AT were related to reductions in fasting and OGTT glucose (P < 0.05), whereas reductions in abdominal subcutaneous AT correlated with reductions in fasting insulin (P < 0.05). CONCLUSIONS: Weight loss induced by diet and aerobic or resistance exercise has similar positive effects on lowering fasting and OGTT insulin values that are greater than those with diet alone. Because changes in glucose and insulin were related to reductions in visceral and abdominal subcutaneous AT, we conclude that reduction in abdominal obesity consequent to diet and exercise-induced weight loss is important for attaining improvements in plasma insulin levels, observations that strengthen the concept that abdominal obesity has an important role in mediating insulin resistance. (+info)
Weight fluctuations could increase blood pressure in android obese women.
Recent studies have documented a relationship between increased morbidity and mortality from cardiovascular diseases and a history of weight cycling (WC) in obese subjects. We performed a cross-sectional analysis in 96 weight-cycling android obese women, matched with 96 non-weight-cycling android obese women by age, body mass index (BMI) and waist-to-hip ratio (WHR), to evaluate any increase in blood pressure (BP) levels in association with WC. The patients were all between 20 and 45 years old, were non-menopausal, did not smoke, did not take any medication, had normal glucose tolerance and were otherwise healthy. A history of WC was established on the basis of at least five weight losses in the previous 5 years due to dieting, with a weight loss of at least 4.5 kg per cycle. We documented higher levels of casual BP in the weight-cycling obese compared with the non-weight-cycling subjects: 147+/-12/90+/-8 mmHg versus 125+/-14/79+/-8 mmHg (P<0.001). The women with WC showed a statistically significant positive correlation between BP and age, weight, BMI, waist circumference, WHR, total weight regained and weight cycling index (WCI). However, in a multiple regression model only the WHR and WCI contributed significantly to the BP variability. These findings could support the hypothesis that it is the combined exposure of central-type obesity and WC that strongly raises the prediction of hypertension. (+info)
Comparison of short-term diet and exercise on insulin action in individuals with abnormal glucose tolerance.
The effects of a 10-day low-calorie diet (LCD; n = 8) or exercise training (ET; n = 8) on insulin secretion and action were compared in obese men (n = 9) and women (n = 7), aged 53 +/- 1 yr, with abnormal glucose tolerance by using a hyperglycemic clamp with superimposed arginine infusion and a high-fat drink. Body mass (LCD, 115 +/- 5 vs. 110 +/- 5 kg; ET, 111 +/- 7 vs. 109 +/- 7 kg; P < 0. 01) and fasting plasma glucose (LCD, 115 +/- 10 vs. 99 +/- 4 mg/dl; ET, 112 +/- 4 vs. 101 +/- 5 mg/dl, P < 0.01) and insulin (LCD, 23.9 +/- 5.6 vs. 15.2 +/- 3.9 microU/ml; ET, 17.6 +/- 1.9 vs. 13.9 +/- 2. 4 microU/ml; P < 0.05) decreased in both groups. There was a 40% reduction in plasma insulin during hyperglycemia (0-45 min) after LCD (peak: 118 +/- 18 vs. 71 +/- 14 microU/ml; P < 0.05) and ET (69 +/- 14 vs. 41 +/- 7 microU/ml; P < 0.05) and trends for reductions during arginine infusion and a high-fat drink. The 56% increase in glucose uptake after ET (4.95 +/- 0.90 vs. 7.74 +/- 0.82 mg. min-1. kg fat-free mass-1; P < 0.01) was significantly (P < 0.01) greater than the 19% increase (5.72 +/- 1.12 vs. 6.80 +/- 0.94 mg. min-1. kg fat-free mass-1; P = not significant) that occurred after LCD. The marked increase in glucose disposal after ET, despite lower insulin levels, suggests that short-term exercise is more effective than diet in enhancing insulin action in individuals with abnormal glucose tolerance. (+info)
Effect of energy restriction, weight loss, and diet composition on plasma lipids and glucose in patients with type 2 diabetes.
OBJECTIVE: To determine the optimal diet for improving glucose and lipid profiles in obese patients with type 2 diabetes during moderate energy restriction. RESEARCH DESIGN AND METHODS: A total of 35 free-living obese patients with type 2 diabetes were assigned to one of three 1,600 kcal/day diets for 12 weeks. The diets were high carbohydrate (10% fat, 4% saturated), high monounsaturated fat (MUFA) (32% fat, 7% saturated), or high saturated fat (SFA) (32% fat, 17% saturated). RESULTS: Diet composition did not affect the magnitude of weight loss, with subjects losing an average of 6.6 +/- 0.9 kg. Energy restriction and weight loss resulted in reductions in fasting plasma glucose (-14%), insulin (-27%), GHb (-14%), and systolic (-7%) and diastolic blood pressure (-10%) levels and the glucose response area (-17%) independent of diet composition. Diet composition did affect the lipoprotein profile. LDL was 10% and 17% lower with the high-carbohydrate and high-MUFA diets, respectively, whereas no change was observed with the high-SFA diet (P < 0.001 for effect of diet). HDL was transiently reduced on the high-carbohydrate diet at weeks 1, 4, and 8, whereas higher fat consumption maintained these levels. The total cholesterol:HDL ratio, although significantly reduced on the high-MUFA diet (P < 0.01), was not different from the other two diets after adjustment for baseline differences. CONCLUSIONS: Energy restriction, independent of diet composition, improves glycemic control; however, reducing SFA intake by replacing SFA with carbohydrate or MUFA reduces LDL maximally during weight loss and to a greater degree than has been shown in weight-stable studies. (+info)