Aerobic fitness, physiologic difficulty and physical activity in Black and White women.

PURPOSE: The purpose of this work was to determine if racial differences in maximum oxygen uptake (VO(2) max) and difficulty in doing submaximum (sub) exercise tasks contribute to activity-related energy expenditure (AEE) and activity-related time equivalent (ARTE) index, an index of time spent in physical activity. METHODS: Subjects were 35 Black and 39 White sedentary premenopausal women group matched for age, weight and body composition. Percent fat was determined by dual energy X-ray absorptiometry, AEE by doubly labeled water and sleeping energy expenditure, ARTE index by AEE and energy cost above sleeping for five exercise tasks, and VO(2) max by a graded exercise test. Subexercise oxygen uptake was measured during walking at 3 mph on the flat and up a 2.5% grade, climbing stairs, and riding a bike ergometer at 50 W. Difficulty of exercise was assessed during the subexercise and taken as heart rate, ventilation, and ratings of perceived exertion (RPE) and expressed as a % of the individual's maximum. RESULTS: VO(2) max was related to AEE (r=0.29, P<0.04) and to ARTE index (r=0.37, P<0.01). All three difficulty measures were related to AEE (r=-0.35 to -0.42, P-values<0.02) and the ARTE index (r=-0.49 to -0.52, all P-values<0.01), with the exception of RPE with ARTE (r=-0.27, P=0.10). Compared to Black women, White women had significantly higher VO(2) max (12%), AEE (45%) and ARTE (50%), and significantly less physiologic difficulty of performing the subexercise tasks: heart rate (5%), ventilation (13%), and RPE (8%). Significant racial differences in AEE and ARTE disappeared after adjusting for any of the three difficulty measures. CONCLUSIONS: These results show that more participation in free-living physical activity is related to greater VO(2) max and less difficulty in being active. In addition, lower levels of physical activity found in Black women may be partially explained by lower VO(2) max and increased difficulty of engaging in physical activities.

Body fat distribution in white and black women: different patterns of intraabdominal and subcutaneous abdominal adipose tissue utilization with weight loss.

BACKGROUND: Intraabdominal adipose tissue (IAAT) is the body fat depot most strongly related to disease risk. Weight reduction is advocated for overweight people to reduce total body fat and IAAT, although little is known about the effect of weight loss on abdominal fat distribution in different races. OBJECTIVE: We compared the effects of diet-induced weight loss on changes in abdominal fat distribution in white and black women. DESIGN: We studied 23 white and 23 black women, similar in age and body composition, in the overweight state [mean body mass index (BMI; in kg/m(2)): 28.8] and the normal-weight state (mean BMI: 24.0) and 38 never-overweight control women (mean BMI: 23.4). We measured total body fat by using a 4-compartment model, trunk fat by using dual-energy X-ray absorptiometry, and cross-sectional areas of IAAT (at the fourth and fifth lumbar vertebrae) and subcutaneous abdominal adipose tissue (SAAT) by using computed tomography. RESULTS: Weight loss was similar in white and black women (13.1 and 12.6 kg, respectively), as were losses of total fat, trunk fat, and waist circumference. However, white women lost more IAAT (P < 0.001) and less SAAT (P < 0.03) than did black women. Fat patterns regressed toward those of their respective control groups. Changes in waist circumference correlated with changes in IAAT in white women (r = 0.54, P < 0.05) but not in black women (r = 0.19, NS). CONCLUSIONS: Despite comparable decreases in total and trunk fat, white women lost more IAAT and less SAAT than did black women. Waist circumference was not a suitable surrogate marker for tracking changes in the visceral fat compartment in black women.

Do adaptive changes in metabolic rate favor weight regain in weight-reduced individuals? An examination of the set-point theory.

BACKGROUND: Obese persons generally regain lost weight, suggesting that adaptive metabolic changes favor return to a preset weight. OBJECTIVE: Our objective was to determine whether adaptive changes in resting metabolic rate (RMR) and thyroid hormones occur in weight-reduced persons, predisposing them to long-term weight gain. DESIGN: Twenty-four overweight, postmenopausal women were studied at a clinical research center in four 10-d study phases: the overweight state (phase 1, energy balance; phase 2, 3350 kJ/d) and after reduction to a normal-weight state (phase 3, 3350 kJ/d; phase 4, energy balance). Weight-reduced women were matched with 24 never-overweight control subjects. After each study phase, assessments included RMR (by indirect calorimetry), body composition (by hydrostatic weighing), serum triiodothyronine (T(3)), and reverse T(3) (rT(3)). Body weight was measured 4 y later, without intervention. RESULTS: Body composition-adjusted RMR and T(3):rT(3) fell during acute (phase 2) and chronic (phase 3) energy restriction (P: < 0.01), but returned to baseline in the normal-weight, energy-balanced state (phase 4; mean weight loss: 12.9 +/- 2.0 kg). RMR among weight-reduced women (4771 +/- 414 kJ/d) was not significantly different from that in control subjects (4955 +/- 414 kJ/d; P: = 0.14), and lower RMR did not predict greater 4-y weight regain (r = 0.27, NS). CONCLUSIONS: Energy restriction produces a transient hypothyroid-hypometabolic state that normalizes on return to energy-balanced conditions. Failure to establish energy balance after weight loss gives the misleading impression that weight-reduced persons are energy conservative and predisposed to weight regain. Our findings do not provide evidence in support of adaptive metabolic changes as an explanation for the tendency of weight-reduced persons to regain weight.

Energy expenditure and free-living physical activity in black and white women: comparison before and after weight loss.

BACKGROUND: The prevalence of obesity is higher in black than in white women. Differences in energy economy and physical activity may contribute to this difference. OBJECTIVE: The objective of this study was to compare free-living energy expenditure and physical activity in black and white women before and after weight loss. DESIGN: Participants were 18 white and 14 black women with body mass indexes (in kg/m(2)) between 27 and 30. Diet, without exercise, was used to achieve a weight loss of >/=10 kg and a body mass index <25. After 4 wk of energy balance in overweight and normal-weight states, body composition was assessed by using a 4-compartment model, sleeping and resting energy expenditures were assessed by using a chamber calorimeter, physiologic stress of exercise and exercise economy were measured by using standardized exercise tasks, and daily energy expenditure was assessed by using doubly labeled water. RESULTS: Weight loss averaged 12.8 kg. Sleeping and resting energy expenditures decreased in proportion to changes in body composition. Weight reduction significantly improved physiologic capacity for exercise in both groups of women, making it easier for them to be physically active. Black women had lower body composition-adjusted energy requirements than did white women-both before and after weight loss-during sleep (9% lower, 519 kJ/d; P < 0.001), at rest (14% lower, 879 kJ/d; P < 0.001), during exercise (6% lower; P < 0. 05), and as a daily total (9% lower, 862 kJ/d; P < 0.06). By contrast, free-living physical activity was similar between the groups. CONCLUSIONS: Weight-reduced women had metabolic rates appropriate for their body sizes. Black women had lower resting and nonresting energy requirements in both overweight and normal-weight states than did white women and did not compensate with greater physical activity, potentially predisposing them to greater weight regain.

Racial differences in energy expenditure and aerobic fitness in premenopausal women.

BACKGROUND: Aerobic fitness, or maximal oxygen uptake (f1.gif" BORDER="0">O(2)max), and energy expenditure (EE) may be lower in African Americans than in whites. OBJECTIVE: The objective of this study was to compare sleeping EE (SEE), resting EE (REE), free-living total EE (TEE), and f1.gif" BORDER="0">O(2)max in African American and white women after adjustment for body composition and free-living activity-related energy expenditure (AEE). DESIGN: Eighteen African American and 17 white premenopausal women were matched for weight, percentage body fat, and age. SEE and REE were measured in a room calorimeter and f1.gif" BORDER="0">O(2)max was measured on a treadmill. Fat-free mass (FFM) and fat mass (FM) (4-compartment model), AEE (doubly labeled water and SEE), and regional lean tissue (dual-energy X-ray absorptiometry) were used as adjustment variables in SEE, REE, TEE, and f1.gif" BORDER="0">O(2)max comparisons. RESULTS: The African American women had significantly more limb lean tissue and significantly less trunk lean tissue than did the white women. The African American women also had significantly lower SEE (6.9%), REE (7.5%), TEE (9.6%), and f1.gif" BORDER="0">O(2)max (13.4%) than did the white women. Racial differences persisted after adjustment for f1.gif" BORDER="0">O(2)max, AEE, FFM, and limb lean tissue but disappeared after adjustment for trunk lean tissue. The f1.gif" BORDER="0">O(2)max difference was independent of all body-composition variables and of AEE. CONCLUSIONS: African American women had lower aerobic fitness than did white women, independent of differences in lean tissue or AEE. Diminished racial differences in SEE, REE, and TEE after adjustment for trunk lean tissue suggest that low EE in African American women is mediated by low volumes of metabolically active organ mass.

Effect of the fat composition of a single meal on the composition and cytotoxic potencies of lipolytically-releasable free fatty acids in postprandial plasma.

Ingestion of a meal increases plasma levels of triglyceride (TG)-rich lipoproteins through the secretion of intestine-derived chylomcirons and liver-derived very low density lipoproteins (VLDL). We have determined the effects of the fat composition of a single meal on the composition of TG in TG-rich lipoproteins (VLDL + chylomicrons) and circulating and lipolytically-releasable free fatty acids (FFA) in postprandial (PP) plasma and on the cytotoxic potencies of the lipolytically-released FFA to cultured arterial wall cells. PP lipemia was induced by feeding fasted normolipidemic human subjects with a meal rich in saturated fat (SF) and another meal rich in polyunsaturated fat (PUF), or vice versa; each meal provided 65% of energy as fat, and polyunsaturated to saturated fatty acid ratios (P/S) of the SF and PUF in the meals were 0.40 and 2.49, respectively. The mean P/S of TG in TG-rich lipoproteins (1.43) and circulating FFA (1.46) in 4 h PP plasma of PUF were significantly higher than those in PP plasma of SF (0.44 and 0.59, respectively) in fasting plasma (0.52 and 0.53, respectively). In vitro lipolysis of fasting and PP serum by purified bovine milk lipoprotein lipase (LpL) resulted in a marked (8.8-12.3-fold) increase in the serum FFA level. The P/S of serum FFA in postlipolysis fasting and PP serum were consistently higher than that of FFA or that of TG associated with TG-rich lipoproteins in prelipolysis fasting and PP serum, indicating that polyunsaturated TG in VLDL and/or chylomicrons is more susceptible than saturated TG to lipolysis. When postlipolysis serum was interacted with cultured endothelial cells and mouse peritoneal macrophages (MPM), the lipolytically-released FFA in PP serum of SF and PUF disrupted the barrier function of endothelial cells and were cytotoxic to cultured MPM; FFA in postlipolysis fasting serum was not cytotoxic. FFA in postlipolysis PP serum of PUF were consistently more potent than that in postlipolysis PP serum of SF. Further study showed that all long-chain monounsaturated FFA and polyunsaturated FFA, but not saturated FFA, incorporated into lipoproteins (LDL) were cytotoxic to cultured MPM. In conclusion, despite the generally well-accepted belief that SF is more atherogenic than PUF, the present study provides in vitro evidence that the lipolytic remnant products of TG-rich lipoproteins produced after a meal rich in PUF are more injurious to arterial wall cells than those produced after a meal rich in SF.

Potencies of lipoproteins in fasting and postprandial plasma to accept additional cholesterol molecules released from cell membranes.

To investigate the role of various lipoproteins in plasma to promote cholesterol efflux from cell membranes, potencies of lipoproteins in normolipidemic fasting and postprandial (PP) plasmas to accept additional cholesterol molecules from cell membranes were determined. We used red blood cells (RBCs) and lipoproteins in fresh blood as donors and acceptors of cell membrane cholesterol, respectively. When fresh fasting plasma (n=24) containing active lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer proteins (CETP) was incubated with a 3-fold excess of autologous RBCs at 37 degrees C for 18 hours, plasma cholesterol levels increased by 19.6% (38.5+/-14.2 mg/dL) owing to an exclusive increase in the CE level. Very low density lipoprotein (VLDL), low density lipoprotein (LDL), and high density lipoprotein (HDL) fractions retained 48.1%, 26.3%, and 25.6% of the net cholesterol mass increase in fasting plasma, resulting in 91%, 8%, and 21% increases in their cholesterol contents, respectively. The PP plasma was 1.3-fold more potent than fasting plasma in promoting cholesterol efflux from RBCs by associating excess cholesterol with chylomicrons, resulting in a 356% increase in the cholesterol content of chylomicrons. These increases in lipoprotein cholesterol content indicate that chylomicrons were about 3.9x, 44x, and 17x more potent than fasting VLDL, LDL, and HDL, respectively, in accepting additional cholesterol molecules released from RBCs. The capacity of PP plasma to promote cholesterol efflux from RBCs was significantly correlated with plasma cholesterol levels (r=0.60, P<0.005), triglycerides (r=0.68, P<0.001), chylomicrons (r=0.90, P<0.001), VLDL (r=0.65, P<0.001), and LDL (r=0.47, P<0.025) but not with the levels of HDL (r= -0.34, P<0.20). In fasting plasma containing a low level of VLDL and HDL, isolated chylomicrons supplemented to the plasma were approximately 9x more potent than HDL in boosting the capacity of plasma to promote cholesterol efflux from RBCs. This study indicates that chylomicrons in PP plasma are the most potent ultimate acceptors of cholesterol released from cell membranes and that a low HDL level is not a factor that limits the ability of PP plasma to promote cholesterol efflux from cell membranes. Our data obtained from an in-vitro system suggest that PP chylomicrons may play a major role in promoting reverse cholesterol transport in vivo, since the transfer of cholesterol from cell membranes to chylomicrons will lead to the rapid removal of this cholesterol by the liver. HDL in vivo may promote reverse cholesterol transport by enhancing the rapid removal of chylomicrons from the circulation, since the rate of clearance of chylomicrons is positively correlated with the HDL level in plasma.

Decreased fat and nitrogen losses in patients with AIDS receiving medium-chain-triglyceride-enriched formula vs those receiving long-chain-triglyceride-containing formula.

OBJECTIVE: The purpose of this study was to compare two enteral formulas, differing only in fat source, for product acceptance, tolerance, and effect on fat malabsorption and nutritional status in subjects with acquired immune deficiency syndrome (AIDS). DESIGN: The double-blind, randomized 15-day trial was divided into a 3-day period in which solid food was consumed followed by a 12-day experimental period in which liquid formulas were consumed. SETTING/SUBJECTS: Twenty-three men and one woman with AIDS and fat malabsorption completed the study. The study was conducted in the General Clinical Research Center, University of Alabama Hospital, University of Alabama at Birmingham. Laboratory assays were performed in the Department of Nutrition Sciences. INTERVENTIONS: After 3 days of consuming a controlled, solid food diet containing 100 g fat per day from mixed sources to document fat malabsorption, subjects were randomly assigned to one of two groups. Each group received a liquid formula containing 35% of energy as fat for 12 days. One group received a formula containing 85% medium-chain triglycerides (MCTs) and the control group received a formula containing 100% long-chain triglycerides. MAIN OUTCOME MEASURES: Determinations included stool number, consistency, weight, and fat and nitrogen content; urine nitrogen and creatinine levels; and body weight. STATISTICAL ANALYSIS PERFORMED: Subject demographic and other baseline characteristics were compared using two-sample t tests; stool and urine assessments were compared between groups at the initial experimental period using two-sample t tests; changes from initial to final experimental periods were assessed by means of analysis of covariance; changes in pooled intake, body weight, and the number and consistency of bowel movements were also assessed using analysis of covariance. All statistical tests were two-tailed and considered significant at P < .05. RESULTS: Within-group comparisons indicated that subjects fed the MCT formula showed significantly decreased stool fat and stool nitrogen content (P = .01 and P = .03, respectively) and increased fat absorption (P = .03), whereas those fed the control formula did not. Differences in stool fat between the groups were not statistically significant. However, the difference in fat absorption from the initial to final formula period was significant (P = .04). Subjects consuming the MCT formula also tended to have a decreased number of bowel movements and abdominal symptoms, whereas subjects fed the control formula showed no improvement. All subjects maintained their body weights. APPLICATIONS: There may be advantages to using an MCT-based formula in the treatment of AIDS-associated malabsorption.

Relationship of co-morbidities of obesity to weight loss and four-year weight maintenance/rebound.

This study examined the effect of weight loss (separate from energy restriction) and weight maintenance/rebound over time on blood pressure, serum lipids, and body composition in 24 obese (mean 137% ideal body weight (IBW)) females with mild to moderate hypertension. Weight loss was induced under tightly controlled General Clinical Research Center conditions until each subject had lost at least 10 kg (mean 13 kg) and attained normal body weight (< 120% IBW). After 4 years subjects returned for repeat evaluation. Weight changes were compared with 24 pair-matched normal weight controls who were also followed for 4 years. With weight loss, significant improvements were seen in standing mean arterial pressure (MAP), serum total cholesterol, low-density lipoprotein cholesterol, and triglycerides. Subjects regained 11 kg (87% of the weight lost) over the 4 year follow-up period while control subjects gained only 2 kg. Subjects who chose self-selected exercise gained less weight than nonexercisers (6 kg vs. 13 kg, P < 0.05). With weight regain there were significant increases in standing and supine MAP, total cholesterol, and high-density lipoprotein (HDL) cholesterol. The amount of weight regained was significantly correlated with standing MAP (r = 0.73), triglycerides (r = 0.43), and HDL cholesterol (r = -0.47). The percentage fat of the weight regained was no greater than that of the weight previously lost. Weight loss, distinct from energy restriction, was associated with improvements in blood pressure and serum lipid levels. The ability to sustain these improvements in the co-morbidities of obesity was directly related to the persistence and magnitude of weight loss maintenance.

Metabolic predictors of obesity. Contribution of resting energy expenditure, thermic effect of food, and fuel utilization to four-year weight gain of post-obese and never-obese women.

This prospective study was designed to identify abnormalities of energy expenditure and fuel utilization which distinguish post-obese women from never-obese controls. 24 moderately obese, postmenopausal, nondiabetic women with a familial predisposition to obesity underwent assessments of body composition, fasting and postprandial energy expenditure, and fuel utilization in the obese state and after weight loss (mean 12.9 kg) to a post-obese, normal-weight state. The post-obese women were compared with 24 never-obese women of comparable age and body composition. Four years later, without intervention, body weight was reassessed in both groups. Results indicated that all parameters measured in the post-obese women were similar to the never-obese controls: mean resting energy expenditure, thermic effect of food, and fasting and postprandial substrate oxidation and insulin-glucose patterns. Four years later, post-obese women regained a mean of 10.9 kg while control subjects remained lean (mean gain 1.7 kg) (P < 0.001 between groups). Neither energy expenditure nor fuel oxidation correlated with 4-yr weight changes, whereas self-reported physical inactivity was associated with greater weight regain. The data suggest that weight gain in obesity-prone women may be due to maladaptive responses to the environment, such as physical inactivity or excess energy intake, rather than to reduced energy requirements.

A prospective study of weight maintenance in obese subjects reduced to normal body weight without weight-loss training.

We examined the pattern of weight maintenance in 24 obese women [body mass index (BMI; in kg/m2) 27.6 +/- 0.4 who were provided foods for a balanced deficit diet until each had lost > or = 10 kg and attained normal body weight (BMI 22.9 +/- 0.4). At 1 y subjects had regained a mean of 42% of their weight loss, which increased to 87% at 4 y. At 4 y 44% of patients had regained < 75%, whereas 37% had regained > or = 100% of the weight originally lost. The amount of weight gained was markedly different from that observed in 24 pair-matched never-obese control subjects over the same length of follow-up. Because the results reported herein were obtained without teaching the subjects weight-control skills, they may be regarded as reflective of the natural history of weight maintenance in this population and may serve as a reference for various weight-intervention programs. The pattern of weight rebound observed in this study is very similar to the pattern observed in combined results from published diet and behavioral-modification programs, which raises important questions regarding the efficacy of these approaches in long-term weight maintenance.

Lipid and insulin concentrations in obese postmenopausal women: separate effects of energy restriction and weight loss.

The separate effects of energy restriction and weight loss on serum lipids were studied in 24 postmenopausal moderately obese women before and after weight loss of greater than 10 kg to normal weight. Fasting serum triglycerides (TGs), total cholesterol (TC), high-density-lipoprotein (HDL) and low-density-lipoprotein (LDL) cholesterol, and insulin were measured at the end of four 10-d in-hospital phases, two before and two after weight loss: phase I, stable weight; phase II, 3350 kJ/d(800 kcal/d), followed by outpatient weight loss; phase III, 3350 kJ/d (800 kcal/d); and phase IV, stable weight. Diet composition and exercise were constant the entire study. Energy-restriction effect was determined by comparing average values in stable-weight phases (I and IV) with low-energy phases (II and III); weight-loss effect was determined by comparing values in obese phases (I and II) with reduced-weight phases (III and IV). Energy restriction lowered TG, TC, LDL cholesterol, the LDL-HDL cholesterol ratio, and insulin and raised HDL cholesterol (all P less than 0.05). Weight loss lowered TG, TC, LDL cholesterol, and insulin (all P less than 0.01) but did not change HDL cholesterol or the LDL-HDL cholesterol ratio. The results suggest that reduction to a weight-steady nonobese state significantly lowers TG, TC, and LDL cholesterol but does not improve HDL cholesterol or the LDL-HDL cholesterol ratio.

Plasma lipoproteins in hyperlipidemic subjects eating iodine-enriched eggs.

Iodine-enriched (IE) eggs are produced by chickens fed a diet containing kelp. These eggs have been reported to reduce plasma cholesterol in humans and experimental animals. The purpose of this study was to determine the effect of the ingestion of one IE egg/day on the plasma lipoprotein cholesterol in borderline and hyperlipidemic individuals ingesting a low-fat diet. One hundred three subjects with entry cholesterol levels greater than 5.17 mmol/L were placed on a low-fat, low-cholesterol diet for 12 weeks. Between weeks 4 and 12, approximately half of the subjects were randomly assigned to either a diet control group (n = 53), or a group who ingested one IE egg/day in addition to this diet (n = 50). Subjects in both the egg group and the diet control group had a significant reduction in total plasma cholesterol (TC) at the end of the study compared with study entry; addition of the egg in the diet did not abolish the TC reduction in the egg group. However, paired comparisons of total and lipoprotein cholesterol levels at the end of the egg intervention period with the end of the initial dietary period demonstrated that the egg group had a significantly greater increase than the diet control group in TC (egg group: 7.2 +/- 1.5% increase; diet controls: 1.5 +/- 0.9% increase; p less than 0.01) and low-density lipoprotein cholesterol (egg group: 9.2 +/- 1.7% increase; diet controls: 3.9 +/- 1.5% increase; p less than 0.01). This effect was most pronounced in subjects with higher initial cholesterol levels and subjects with mixed hyperlipidemia (elevated cholesterol and triglyceride). Results suggest that these particular groups of subjects are most susceptible to cholesterol changes associated with ingestion of IE eggs.

Saturated fats, cholesterol, and dietary compliance.

BACKGROUND: Lack of response to a cholesterol-lowering diet can be caused by physiological nonresponsiveness, inadequate knowledge, or inability to change dietary habits (poor compliance). The purpose of this study was to evaluate the dietary compliance of hyperlipidemic individuals who received intensive initial dietary education and followup, and who showed an initial reduction of their plasma cholesterol levels. METHODS: One hundred five individuals with fasting cholesterol levels of 5.17 mmol/L (200 mg/dL) or greater received intensive education and follow-up on the American Heart Association Step I diet during an initial 12-week period. The participants provided 3-day dietary records every week, and fasting lipoprotein analysis was performed biweekly. Six months after termination of this period, the subjects were requested to return for a follow-up evaluation of their lipoprotein profile and dietary adherence. RESULTS: Seventy-three (70%) of the subjects returned for a follow-up evaluation of lipoprotein cholesterol levels. Of these, 42 (58%) had a 10% or greater average initial decrease in total cholesterol levels at weeks 3 and 4 ("baseline"), and they were considered to be "high responders." At the 6-month follow up, the average plasma cholesterol level in these responders remained 6.4% below that at entry level, but it had increased by 19% compared with baseline values (6.30 mmol/L [244 mg/dL] vs 5.43 mmol/L [210 mg/dL], respectively). Corresponding significant increases at 6 months were found in high-density lipoprotein cholesterol (8%), low-density lipoprotein cholesterol (16%), and very-low-density lipoprotein cholesterol (66%) levels. Analysis of dietary histories revealed that dietary cholesterol and percent calories from fat increased significantly, but remained within the recommended guidelines. However, the increase in percent calories from saturated fat (from 10.0% +/- 0.5% to 14.4% +/- 1.0% [mean +/- SEM]) deviated markedly from these guidelines. CONCLUSIONS: The results suggest the long-term compliance to the reduction of dietary saturated fat remains a problem, even in individuals who receive intensive initial training and show an early favorable response. Follow-up evaluation of hyperlipidemic patients who are receiving dietary therapy should take into account this behavioral pattern. It remains to be determined whether continuing supervision and better nutritional labeling will facilitate dietary compliance.

Obesity-related hypertension: evaluation of the separate effects of energy restriction and weight reduction on hemodynamic and neuroendocrine status.

PURPOSE: Although weight reduction generally lowers blood pressure, it is unclear whether the response is due to concurrent dietary changes or to reduced body mass itself. In this study, the independent effects of energy restriction and weight reduction were examined prospectively in 24 obese, hypertensive, normoglycemic women whose dietary intake was tightly controlled. SUBJECTS AND METHODS: Sodium, potassium, and calcium intake, the polyunsaturated/saturated fat ratio, and the proportional composition of carbohydrate, fat, and protein were constant throughout the 5-month protocol. Hemodynamic and neuroendocrine status was evaluated in four 10-day hospital phases: two prior to weight loss (energy balance and then 800-kcal intake), and two after an average loss of 13 kg to normal body weight (800 kcal and then return to energy balance). RESULTS: Fasting serum insulin, triiodothyronine:reverse triiodothyronine ratio, resting metabolic rate, and heart rate declined, and sodium and potassium balances were negative during energy restriction. Catecholamines, renin, aldosterone, plasma volume, cardiac output, and blood pressure showed no consistent response to changes in energy intake. By contrast, weight reduction independently lowered blood pressure, plasma volume, cardiac output, and plasma renin activity. Body fat pattern remained unchanged. CONCLUSION: These results demonstrate that weight loss has a blood pressure-lowering effect that is distinct from energy restriction and that is related to changes in blood volume and cardiac output.