PubMed Health⌕ Search

Biomedical subjects

N L Keim

Publications and source records attributed to N L Keim.

At least 19 recordsLinked to original sources
PubMed2005

Raman spectroscopic analysis of biochemical changes in individual triglyceride-rich lipoproteins in the pre- and postprandial state.

Individual triglyceride-rich lipoprotein (TGRL) particles derived from human volunteers are nondestructively analyzed by laser tweezers Raman microspectroscopy, and information on their composition and distribution is obtained. The Raman signature of single optically trapped very low-density lipoproteins (VLDL), a subclass of TGRL, which play an important role in cardiovascular disease, exhibits distinct peaks associated with molecular vibrations of fatty acids, proteins, lipids, and structural rearrangements of lipids. Our analysis of pre- and postprandial VLDL exhibits the signature of biochemical changes in individual lipoprotein particles following the consumption of meals. Interaction of VLDL with endothelium leads to the breakdown of complex triacylglycerols and the formation of a highly ordered core of free saturated fatty acids in the particle. A particle distribution analysis reveals trends in the degree to which this process has occurred in particles at different times during the postprandial period. Differences in particle distributions based on the different ratios of polyunsaturated to saturated fats in the consumed meals are also easily discerned. Individual lipoprotein particles hydrolyzed in vitro through addition of lipoprotein lipase (LpL) exhibit strikingly similar changes in their Raman spectra. These results demonstrate the feasibility of monitoring the dynamics of lipid metabolism of individual TGRL particles as they interact with LpL in the endothelial cell wall using Raman spectroscopy.

Adult↗
PubMed2004

Low bone mass in premenopausal chronic dieting obese women.

BACKGROUND: Obese premenopausal women are thought to be at low risk for osteoporosis due to increased body weight and effects of estrogen on weight-bearing bone. OBJECTIVE: To examine the effect of restrained eating on obese women, we examined bone mineral density (BMD) and content (BMC) of the spine and femur in obese women who were restrained eaters, with emphasis on the relationship between BMC and determinants of bone mass, and current eating behaviors, dietary intake, physical activity, and indices of calcium regulation, bone metabolism, stress and inflammation. DESIGN: A total of 78 obese, Caucasian, female, restrained eaters, ages 30-45 y, were enrolled in a weight lose program. Height, weight, bone turnover markers, serum parathyroid hormone (PTH), cortisol, c-reactive protein (CRP), dietary intake, eating behaviors, physical activity, and BMD and BMC were measured. SETTING: This study was conducted at the University of California, in Davis, CA, USA. RESULTS: In all, 31% of women had osteopenia or osteoporosis (OSTEO). In the OSTEO group, 87.5% of women had osteoporosis or osteopenia of the lumbar spine and 12.5% of the women had osteoporosis or osteopenia in femur. A significant positive correlation between BMC and energy expenditure (r=0.256), and a significant negative correlation between BMC and number of times on a weight loss diet (r=-0.250) and cognitive restraint (r=-0.239) were observed. No significant differences were observed between OSTEO women and nonosteoporotic women for current eating behaviors, dietary intake, physical activity habits, bone turnover, calcium regulation, stress, or inflammation. CONCLUSIONS: Obese restrained eaters are at risk for low bone mass. Prior dieting may be responsible. Chronic dieters should be encouraged to decrease their dietary restraint, develop healthy eating habits and increase physical activity.

Adult↗
PubMed2002

Evaluating a 'non-diet' wellness intervention for improvement of metabolic fitness, psychological well-being and eating and activity behaviors.

CONTEXT: Current public health policy recommends weight loss for obese individuals, and encourages energy-restricted diets. Others advocate an alternative, 'non-diet' approach which emphasizes eating in response to physiological cues (eg hunger and satiety) and enhancing body acceptance. OBJECTIVE: To evaluate the effects of a 'health-centered' non-diet wellness program, and to compare this program to a traditional 'weight loss-centered' diet program. DESIGN: Six-month, randomized clinical trial. SETTING: Free-living, general community. PARTICIPANTS: Obese, Caucasian, female, chronic dieters, ages 30-45 y (n=78). INTERVENTIONS: Six months of weekly group intervention in a non-diet wellness program or a traditional diet program, followed by 6 months of monthly after-care group support. OUTCOME MEASURES: Anthropometry (weight, body mass index); metabolic fitness (blood pressure, blood lipids); energy expenditure; eating behavior (restraint, eating disorder pathology); psychology (self-esteem, depression, body image); attrition and attendance; and participant evaluations of treatment helpfulness. Measures obtained at baseline, 3 months, 6 months and 1 y. RESULTS: (1 y after program initiation): Cognitive restraint increased in the diet group and decreased in the non-diet group. Both groups demonstrated significant improvement in many metabolic fitness, psychological and eating behavior variables. There was high attrition in the diet group (41%), compared to 8% in the non-diet group. Weight significantly decreased in the diet group (5.9+/-6.3 kg) while there was no significant change in the non-diet group (-0.1+/-4.8 kg). CONCLUSIONS: Over a 1 y period, a diet approach results in weight loss for those who complete the intervention, while a non-diet approach does not. However, a non-diet approach can produce similar improvements in metabolic fitness, psychology and eating behavior, while at the same time effectively minimizing the attrition common in diet programs.

Adult↗
PubMed2001

Conjugated linoleic acid supplementation in humans: effects on fatty acid and glycerol kinetics.

Recent studies with mouse adipocytes have shown that dietary conjugated linoleic acid (CLA) may reduce body fat by increasing lipolysis. The present study examined the effect of CLA supplementation on fatty acid and glycerol kinetics in six healthy, adult women who were participating in a controlled metabolic ward study. These women were fed six CLA capsules per day (3.9 g/d) for 64 d following a baseline period of 30 d. The subjects were confined to a metabolic suite for the entire 94-d study, where diet and activity were controlled and held constant. The rate of appearance (Ra) of glycerol, which indicates lipolytic rates, was similar at baseline and after 4 wk of CLA supplementation at rest (1.87 +/- 0.21 and 2.00 +/- 0.39 micromol/kg/min, respectively) and during exercise (7.12 +/- 0.74 and 6.40 +/- 0.99 micromol/kg/min, respectively). Likewise, the Ra of free fatty acids (FFA) was not significantly different after 4 wk of dietary CLA at rest (2.72 +/- 0.06 and 2.74 +/- 0.12 micromol/kg/min, respectively) or during exercise (6.99 +/- 0.40 and 5.88 +/- 0.29 micromol/kg/min, respectively). CLA supplementation also had no effect on the percentage of FFA released from lipolysis that were re-esterified. The apparent rate of FFA re-esterification was 65.2 +/- 4.2% at rest and 32.1 +/- 3.44% during exercise. Four weeks of CLA supplementation had no significant effect on fatty acid or glycerol metabolism in healthy, weight-stable, adult women.

Adult↗
PubMed2000

Conjugated linoleic acid supplementation in humans: effects on body composition and energy expenditure.

Recent animal studies have demonstrated that dietary conjugated linoleic acid (CLA) reduces body fat and that this decrease may be due to a change in energy expenditure. The present study examined the effect of CLA supplementation on body composition and energy expenditure in healthy, adult women. Seventeen women were fed either a CLA capsule (3 g/d) or a sunflower oil placebo for 64 d following a baseline period of 30 d. The subjects were confined to a metabolic suite for the entire 94 d study where diet and activity were controlled and held constant. Change in fat-free mass, fat mass, and percentage body fat were unaffected by CLA supplementation (0.18+/-0.43 vs. 0.09+/-0.35 kg; 0.01+/-0.64 vs. -0.19+/-0.53 kg; 0.05+/-0.62 vs. -0.67+/-0.51%, placebo vs. CLA, respectively). Likewise, body weight was not significantly different in the placebo vs. the CLA group (0.48+/-0.55 vs. -0.24+/-0.46 kg change). Energy expenditure (kcal/min), fat oxidation, and respiratory exchange ratio were measured once during the baseline period and during weeks 4 and 8 of the intervention period. At all three times, measurements were taken while resting and walking. CLA had no significant effect on energy expenditure, fat oxidation, or respiratory exchange ratio at rest or during exercise. When dietary intake was controlled, 64 d of CLA supplementation at 3 g/d had no significant effect on body composition or energy expenditure in adult women, which contrasts with previous findings in animals.

Adult↗
PubMed2000

Conjugated linoleic acid supplementation in humans: effects on circulating leptin concentrations and appetite.

Conjugated linoleic acid (CLA) has been demonstrated to reduce body fat in animals. However, the mechanism by which this reduction occurs is unknown. Leptin may mediate the effect of CLA to decrease body fat. We assessed the effects of 64 d of CLA supplementation (3 g/d) on circulating leptin, insulin, glucose, and lactate concentrations in healthy women. Appetite was assessed as a physiological correlate of changes in circulating leptin levels. Analysis of plasma leptin concentrations adjusted for adiposity by using fat mass as a covariate showed that CLA supplementation significantly decreased circulating leptin concentrations in the absence of any changes of fat mass. Mean leptin levels decreased over the first 7 wk and then returned to baseline levels over the last 2 wk of the study in the CLA-treated group. Appetite parameters measured at around the time when the greatest decreases in leptin levels were observed showed no significant differences between supplementation and baseline determinations in the CLA-supplemented group or between the CLA and placebo-supplemented groups. There was a nonsignificant trend for mean insulin levels to increase toward the end of the supplementation period in CLA-treated subjects. CLA did not affect plasma glucose and lactate over the treatment period. Thus, 64 d of CLA supplementation in women produced a transient decrease in leptin levels but did not alter appetite. CLA did not affect these parameters in a manner that promoted decreases of adiposity.

Adipose Tissue↗
PubMed2000

Influence of cognitive eating restraint on total-body measurements of bone mineral density and bone mineral content in premenopausal women aged 18-45 y: a cross-sectional study.

BACKGROUND: We examined the relation between cognitive eating restraint (CER) and total-body measurements of bone mineral density (BMD) and bone mineral content (BMC). OBJECTIVE: Our objective was to determine whether women with CER had lower total-body BMD and BMC than did other women. DESIGN: Premenopausal women, 90-150% of ideal weight, had measurements of their BMD and BMC made and completed questionnaires on physical activity, weight history, body size satisfaction, dieting history, eating behavior, and childbearing history. Bone measurements were examined for differences between groups with low and high CER scores by using analysis of covariance and quartiles of body weight to adjust for body size differences. CER was assessed by using the Three-Factor Eating Inventory and was defined as a score > or =9; normal eating restraint (NER) was defined by a score <9. Total-body BMC, BMD, and fat and lean masses were measured by dual-energy X-ray absorptiometry. RESULTS: Fifty-two percent of the women were classified as having CER. Women with CER were significantly more dissatisfied with their bodies. Analysis of covariance, with weight as the covariate, indicated a significant difference in BMC between women in preplanned pairs from the 5 lowest and 5 highest CER levels. No significant differences in BMD were observed between groups. Significantly lower BMC was found in women with high CER scores and body weights <71 kg than in those with high CER scores and weights > or =71 kg. CONCLUSIONS: BMC was significantly differently between women with low and high CER scores. BMC was significantly lower in women with body weights <71 kg and classified with CER. Lower BMC in women with high CER scores may indicate an increased risk of osteoporosis.

Adolescent↗
PubMed1998

Relation between circulating leptin concentrations and appetite during a prolonged, moderate energy deficit in women.

BACKGROUND: On the basis of observations in rodents, leptin is thought to play a key role in the regulation of energy expenditure and food intake, but less is known of its influence on ingestive behavior and energy balance in humans. OBJECTIVE: We examined the effect in women of a chronic energy deficit on plasma leptin concentrations and self-reported appetite and explored possible relations between leptin and appetite sensations. DESIGN: Twelve healthy women (body mass index, in kg/m2: 23-37) participated in a metabolic ward study in which 3 wk of neutral energy balance was followed by 12 wk of energy deficit (energy intake reduced by 2 MJ/d and energy expenditure increased by 0.8 MJ/d). Body weight and composition were monitored, fasting leptin concentrations were measured 4 times, and feelings of hunger, fullness, desire to eat, and prospective consumption were monitored hourly throughout the day on 7 selected days. RESULTS: Adiposity-adjusted leptin decreased by 54% after 1 wk of a moderate energy deficit and remained low after 6 and 12 wk. Leptin was associated with self-reported hunger, desire to eat, and prospective consumption (range of r: -0.6 to -0.7, P < 0.01). The greatest hunger increase coincided with the largest percentage drop in circulating leptin and the lowest final leptin concentration. The relation between leptin and hunger was not influenced by amount of weight or body fat loss. CONCLUSIONS: These findings support the idea that leptin is a physiologic regulator of hunger during energy deficits in humans; the role of leptin in the long-term regulation of food intake warrants further study.

Adipose Tissue↗
PubMed1997

Weight loss is greater with consumption of large morning meals and fat-free mass is preserved with large evening meals in women on a controlled weight reduction regimen.

The purpose of this study was to determine whether meal ingestion pattern [large morning meals (AM) vs. large evening meals (PM)] affects changes in body weight, body composition or energy utilization during weight loss. Ten women completed a metabolic ward study of 3-wk weight stabilization followed by 12 wk of weight loss with a moderately energy restricted diet [mean energy intake +/- SD = 107 +/- 6 kJ/(kg.d)] and regular exercise. The weight loss phase was divided into two 6-wk periods. During period 1, 70% of daily energy intake was taken as two meals in the AM (n = 4) or in the PM (n = 6). Subjects crossed over to the alternate meal time in period 2. Both weight loss and fat-free mass loss were greater with the AM than the PM meal pattern: 3.90 +/- 0.19 vs. 3.27 +/- 0.26 kg/6 wk, P < 0.05, and 1.28 +/- 0.14 vs. 0.25 +/- 0.16 kg/6 wk, P < 0.001, respectively. Change in fat mass and loss of body energy were affected by order of meal pattern ingestion. The PM pattern resulted in greater loss of fat mass in period 1 (P < 0.01) but not in period 2. Likewise, resting mid-afternoon fat oxidation rate was higher with the PM pattern in period 1 (P < 0.05) but not in period 2, corresponding with the fat mass changes. To conclude, ingestion of larger AM meals resulted in slightly greater weight loss, but ingestion of larger PM meals resulted in better maintenance of fat-free mass. Thus, incorporation of larger PM meals in a weight loss regimen may be important in minimizing the loss of fat-free mass.

Adipose Tissue↗
PubMed1996

Effect of exercise and dietary restraint on energy intake of reduced-obese women.

Self-selected food intake of 15 reduced-obese women living in a metabolic ward was studied for 14 consecutive days to determine the effect of exercise and other metabolic and behavioral variables on energy intake. A choice of prepared food items were offered at breakfast, lunch and dinner, and a variety of additional food items were available continuously 24 h/day. Subjects performed either moderate intensity aerobic exercise (A-EX) (n = 8) expending 354 +/- 76 kcal/session or low intensity resistance weight training (R-EX)(n =7) expending 96 +/- kcal/session, 5 days/week. Mean energy intakes (kcal/day, +/- SEM) of the exercise groups were similar: 1867 +/- 275 for A-EX, 1889 +/- 294 for R-EX. Mean energy intakes of individuals ranged from 49 to 157% of the predetermined level required for weight maintenance. Resting metabolic rate per kg 0.75 and the Eating Inventory hunger score contributed significantly to the between subject variance in energy intake, whereas exercise energy expenditure did not. Regardless of exercise, eight women consistently restricted their energy intake (undereaters), and seven other consumed excess energy (overeaters). Overeaters were distinguished by higher Eating Inventory disinhibition (P = 0.023) and hunger (p = 0.004) scores. The overeaters' diet had a higher fat content 34 +/- 1% (p = 0.007). Also, overeaters took a larger percentage of their daily energy, than that of undereaters, 27 +/- 1 energy intake in the evening, 13 +/- 2%, compared to undereaters, 7 +/- 1% (p = 0.005). We conclude that the Eating Inventory is useful for identifying reduced-obese women at risk of overeating, and these individuals may benefit from dietary counseling aimed at reducing fat intake and evening snacking.

Adult↗
PubMed1996

Body fat percentage and gender: associations with exercise energy expenditure, substrate utilization, and mechanical work efficiency.

Energy expenditure (EE) was measured at specific steady-state work rates to determine if body fat percentage or gender was associated with exercise EE, substrate oxidation, or work efficiency. Body fat percentage (leaner vs. fatter men, 9-15% vs. 20-25% fat; leaner vs. fatter women, 16-24% vs. 32-48% fat) was not related to work efficiency or submaximal EE. Fatness affected substrate oxidation in men but not in women. Compared to fatter men, leaner men had higher fat oxidation (6.7 +/- 1.6 vs. 1.4 +/- 2.0 mg.kg fat-free mass [FFM]-1.min-1; p < .01) and lower carbohydrate oxidation (26.6 +/- 4.2 vs. 39.3 +/- 5.0 mg.kg FFM-1.min-1; p < .01) at 60% VO2max. When men and women of similar fatness and relative aerobic capacity were compared, men had higher EE measured as kilojoules per minute but similar rates of EE and substrate oxidation per kilogram of FFM at 40-60% VO2max. It was concluded that body FFM, not fatness, is a determinant of exercise EE, whereas fatness is associated with differences in exercise substrate oxidation in men. Along with aerobic fitness, gender and fatness should be considered in future studies of exercise substrate oxidation.

Adipose Tissue↗
PubMed1995

Evaluation of body composition by dual energy x-ray absorptiometry and two different software packages.

Dual energy x-ray absorptiometry (DXA) measures body composition, tissue distribution, bone mineral content (BMC), and bone mineral density (BMD). Differences are possible due to software versions. This investigation examined body composition, tissue distribution, BMC, and BMD measurements using a DXA (Lunar Corp., Madison, WI) with different software packages (versions 3.4 and 3.6R). Fifteen women, ages 20-40 yr, enrolled in a weight-loss study (body mass index = 28) and volunteered for body composition assessment by densitometry. BMC, BMD, and tissue distribution measurements were made using DXA. Results were analyzed once each with software versions 3.4 and 3.6R. BMC + total soft tissue, measured using DXA, was comparable to measured body weight (3.4 = 76.3 kg; 3.6R = 76.5 kg; weight = 76.5 kg). Lower BMC and BMD (5.5% and 1.8%, P < 0.01) were observed with 3.6R. Arm tissue mass was lower (1,530 g; P < 0.01) and fat declined (1,069 g; P < 0.01) with 3.6R. Leg tissue mass decreased 487 g (P < 0.01), but fat tissue increased (526 g, P < 0.01) with 3.6R. A larger fat mass (1,492 g) and lower lean mass (1,115 g) were observed with 3.6R compared with 3.4. Percent fat values by densitometry using DXA 3.4 and 3.6R were 38.1%, 39.9, and 41.9%, respectively. These results demonstrated differences in total body composition, lean and fat tissue distribution, and bone measurements from DXA software versions.

Absorptiometry, Photon↗
PubMed1994

Effects of a carotene-deficient diet on measures of oxidative susceptibility and superoxide dismutase activity in adult women.

The effect of consuming a low carotene diet (approximately 60 micrograms carotene/day) on oxidative susceptibility and superoxide dismutase (SOD) activity in women living in a metabolic research unit was evaluated. The diet had sufficient vitamins A, E, and C. The women ate the diet supplemented with 1500 micrograms/day beta-carotene for 4 days (baseline), then the unsupplemented diet for 68 days (depletion), followed by the diet supplemented with > 15,000 micrograms/day carotene for 28 days (repletion). Production of hexanal, pentanal, and pentane by copper-oxidized plasma low density lipoproteins from carotene-depleted women was greater than their production of these compounds when repleted with carotene. Erythrocyte SOD activity was depressed in carotene-depleted women; it recovered with repletion. Thiobarbituric acid reactive substances in plasma of carotene-depleted women were elevated and diminished with repletion. Dietary carotene seems to be needed, not only as a precursor of vitamin A, but also to inhibit oxidative damage and decrease oxidation susceptibility.

Adult↗
PubMed1994

The effects of endurance exercise with and without a reduction of energy intake on fat-free mass and the composition of fat-free mass in obese women.

OBJECTIVE: The objective of this study was to evaluate the effects of endurance exercise on fat-free mass and nitrogen balance, with energy restriction or with energy intake to meet non-exercise needs in obese women. DESIGN: The study was a 14-week metabolic control study with a 2-week baseline period for dietary stabilization followed by a 12-week period of exercise (E) with or without energy restriction (D), E or D+E. SETTING: Metabolic research unit of the Western Human Nutrition Research Center. SUBJECTS: Ten obese women between the ages of 19 and 37 years volunteered as subjects. Body weight ranged from 19% to 41% IBW and body fat was 31-40% of body weight. INTERVENTION: Women were assigned to either an energy-restricted or energy-'adequate' group so that group means for weight, body fat, FFM, predicted VO2max and RMR were similar. Data were polled for the 2-week baseline period and in 3-week intervals during the intervention period. RESULTS: The data indicated that E had a slower rate of weight loss and a lower loss of FFM than D+E. Nitrogen balance was more positive in E than D+E. Negative N balance occurred in the D+E group when blood was drawn. There was no decrease in N excretion to compensate for blood losses. N balance for E was positive throughout the study. CONCLUSION: Changes in FFM, assessed by total body electrical conductivity, were different from the results obtained by classic nitrogen balance. This suggests that losses were due to fluid losses, which were confirmed by deuterium dilution procedures. This study demonstrated that body protein stores remained intact during periods of increased energy expenditure and dietary restriction in obese women.

Adipose Tissue↗
PubMed1994

Moderate diet restriction alters the substrate and hormone response to exercise.

Substrate and hormone responses to submaximal exercise were studied in 10 overweight women (119-141% ideal body weight) to learn if a moderately restricted diet would influence the responses. Subjects consumed diets with adequate energy (ADEX), N = 5, or low energy (LDEX)--50% reduction in energy, N = 5. Three times during the 12-wk study, blood was drawn before and immediately following exercise; results were combined since there were no differences between replicates. Postexercise free fatty acids and glycerol increased to 465 +/- 27 mg.l-1 in LDEX but only to 245 +/- 19 mg.l-1 in ADEX. Postexercise insulin increased to 129 +/- 13 pmol.l-1 in LDEX, but did not increase in ADEX. Postexercise growth hormone increased to 10.5 +/- 1.0 microgram.l-1 in ADEX but only to 6.6 +/- 1.0 microgram.l-1 in LDEX. All postexercise increases within diet groups were highly significant (P < 0.0001), and the postexercise responses between diet groups were also different (P < 0.01). Respiratory gas exchange indicated that both groups increased fat utilization during exercise, but diet restriction altered postexercise hormones so that fat mobilization and utilization might be inhibited. The postexercise recovery period should be studied further to determine whether diet restriction results in a sustained altered hormone pattern that would curtail lipolysis and possibly limit body fat loss.

3-Hydroxybutyric Acid↗
PubMed1991

Physiological and biochemical variables associated with body fat loss in overweight women.

During a weight loss study conducted on a metabolic unit, five women lost an average of 8.7 +/- 0.7 kg of body fat mass (FM) with a 12 week treatment of low energy diet plus exercise. Another group of five women lost 4.4 +/- 0.7 kg FM with a 12 week treatment of an adequate diet plus exercise. Within each treatment, the amount of FM lost varied by approximately 2-fold. To explain the variability in FM loss, we tested its association by multiple regression analysis with several physiological and biochemical measurements obtained during a 2 week stabilization period or early in the treatment period. The variable most closely correlated with FM loss was plasma free fatty acid levels following exercise (EX-FFA). This variable alone accounted for 79 percent of the variation in FM loss. EX-FFA was simple to measure and was repeatedly correlated with FM loss, whether FFA values of the first exercise test or EX-FFA values obtained later in the experimental period were used. Of the physiological variables tested, the rate of fat calories expended in response to a test meal was correlated with FM loss and accounted for 71 percent of the variation. Upon subsequent testing, however, this relationship was not repeatable. When a treatment group designation (dummy-coded variable) was added to the regression analysis, the rate of fat calories expended at rest (FATRMR) was related to FM loss. Together, FATRMR and the dummy-coded variable accounted for 87 percent of the variation in FM loss. In a separate multiple regression equation, the combination of EX-FFA and the dummy-coded variable also accounted for 87 percent of the variation in FM loss. Further evaluation of these relationships is required to determine if EX-FFA or FATRMR would be useful as predictors of FM loss under conditions of weight loss where individuals are living freely in the community and consuming a variety of diets.

Adipose Tissue↗
PubMed1990

Energy expenditure and physical performance in overweight women: response to training with and without caloric restriction.

The metabolic effects of exercise training and the influence of a moderate calorie restriction on the training response were examined in overweight women. Ten healthy women, 119% to 141% of desirable weight, completed the 14-week study. After a 2-week stabilization period, in which diets were designed to maintain body weight (BW), five women were assigned to a 12-week experimental program of diet and exercise (D + EX) that included a 50% reduction in energy intake and a program of moderate intensity aerobic exercise 6 days per week. The other five women were assigned to the same daily exercise (EX) and continued to consume the stabilization diet. Periodic measurements of resting metabolic rate (RMR), thermic effect of food (TEF), energy cost of exercise, and predicted maximal aerobic capacity (VO2 max) were obtained, and the respiratory quotient (RQ) was determined during rest and exercise. Body composition was monitored weekly. Tests of strength and anaerobic capacity were conducted. D + EX lost an average of approximately 1.1 kg/wk, which was 67% fat, 33% lean. EX lost approximately 0.5 kg/wk, which was 86% fat, 14% lean. In both groups, the exercise program resulted in an 11% to 13% improvement in VO2 max and an 8% to 16% decrease in energy expenditure at submaximal workloads. The caloric restriction significantly increased fat utilization during exercise. The RMR declined 9% in D + EX, from 1,550 to 1,411 kcal/d, whereas it was maintained in EX, 1,608 to 1,626 kcal/d. The decrease in RMR observed in D + EX was consistent with the loss of fat-free mass (FFM).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗