African American women exhibit similar adherence to intervention but lose less weight due to lower energy requirements.

BACKGROUND: African American (AA) women have been shown to lose less weight than Caucasian women in response to behavioral interventions. Our objective was to examine adherence to intervention and metabolic factors that may explain this difference. DESIGN AND SUBJECTS: We examined longitudinal changes in body weight and energy expenditure (EE), and objective assessment of physical activity (PA) and energy intake (EI) during 6 months of a weight-loss intervention program, including prescribed calorie restriction and increased PA in 66 Caucasian and 39 AA severely obese women. Comparisons were also made in 25 Caucasian and 25 AA women matched for initial body weight. RESULTS: The AA women lost 3.6 kg less weight than Caucasian women. Total daily EE (TDEE) and resting metabolic rate (RMR) adjusted for fat free mass (FFM) were significantly lower in the AA women, whereas the decrease in RMR in response to weight loss was greater in Caucasian women. Adherence to the prescribed PA and change in PA in response to intervention were similar in AA and Caucasian women. Prescribed EI (1794±153 and 1806±153 kcal per day) and measured EI during intervention (2591±371 vs 2630±442 kcal per day) were nearly identical in matched AA and Caucasian women. However, the AA women lost significantly less body weight due to lower energy requirements (2924±279 vs 3116±340 kcal per day; P<0.04), resulting in a lower energy deficit (333±210 vs 485±264 kcal per day). CONCLUSION: Adherence to the behavioral intervention was similar in AA and Caucasian women. However, neglecting to account for the lower energy requirements in AA women when calculating the energy prescription resulted in a lower level of calorie restriction and, hence, less body weight loss. Therefore, to achieve similar weight loss in AA women, the prescribed caloric restriction cannot be based on weight alone, but must be lower than in Caucasians, to account for lower energy requirements.

High energy expenditure masks low physical activity in obesity.

OBJECTIVE: To investigate energy expenditure in lean and obese individuals, focusing particularly on physical activity and severely obese individuals. DESIGN: Total daily energy expenditure (TDEE) was assessed using doubly labeled water, resting metabolic rate (RMR) by indirect calorimetry, activity energy expenditure (AEE) by difference and time spent in physical activity by multisensor activity monitors. SUBJECTS: In all, 177 lean, Class I and severely obese individuals (age 31-56 years, body mass index 20-64 kg m(-2)) were analyzed. RESULTS: All components of energy expenditure were elevated in obese individuals. For example, TDEE was 2404±95 kcal per day in lean and 3244±48 kcal per day in Class III obese individuals. After appropriate adjustment, RMR was similar in all groups. Analysis of AEE by body weight and obesity class indicated a lower AEE in obese individuals. Confirming lower physical activity, obese individuals spent less time engaged in moderate-to-vigorous physical activity (2.7±1.3, 1.8±0.6, 2.0±1.4 and 1.2±1.0 h per day in lean, Class I, Class II and Class III individuals) and more time in sedentary behaviors. CONCLUSIONS: There was no indication of metabolic efficiency in even the severely obese, as adjusted RMR was similar across all groups. The higher AEE observed in the obese is consistent with a higher cost of activities due to higher body weight. However, the magnitude of the higher AEE (20-25% higher in obese individuals) is lower than expected (weight approximately 100% higher in Class III individuals). Confirming a lower volume of physical activity in the obese, the total time spent in moderate-to-vigorous physical activity and average daily metabolic equivalent of task level were lower with increasing obesity. These findings demonstrate that high body weight in obese individuals leads to a high TDEE and AEE, which masks the fact that they are less physically active, which can be influenced by duration or intensity of activity, than in lean individuals.

Evaluating the contribution of differences in lean mass compartments for resting energy expenditure in African American and Caucasian American children.

BACKGROUND: Resting energy expenditure (REE), adjusted for total lean mass (LM), is lower in African American (AA) than Caucasian American (CA) children. Some adult studies suggest that AA-CA differences in lean mass compartments explain this REE difference. Similar data are limited in children. OBJECTIVE: To evaluate differences in compartment-specific lean mass between AA and CA children and examine the individual contributions of high-metabolic rate-at-rest trunk lean mass (TrLM) and low-metabolic-rate-at-rest appendicular lean mass (AppLM) for AA-CA differences in REE. METHODS: We studied a convenience sample of 594 AA (n = 281) and CA (n = 313) children. REE was measured by using indirect calorimetry; dual-energy X-ray absorptiometry was used to assess body composition. ANCOVAs were performed to examine AA-CA differences in TrLM, AppLM and REE. After accounting for age, sex, height, pubertal development, bone mass and adiposity, REE was evaluated adjusting for total LM (model A) and separately adjusting for TrLM and AppLM (model B). RESULTS: African American children had greater adjusted AppLM (17.8 ± 0.2 [SE] vs. 16.0 ± 0.2 kg, p < 0.001) and lower TrLM (17.2 ± 0.2 vs. 17.7 ± 0.2 kg, p = 0.022) than CA children. REE adjusted for total LM was 77 ± 16 kcal/d lower in AA than CA (p < 0.001). However, after accounting separately for AppLM and TrLM, the discrepancy in REE between the groups declined to 28 ± 19 kcal/d (p = 0.14). In the adjusted model, both TrLM (p < 0.001) and AppLM (p < 0.027) were independently associated with REE. CONCLUSION: In children, AA-CA differences in REE appear mostly attributable to differences in body composition. Lower REE in AA children is likely due to lower TrLM and greater AppLM.

Comparison of bone density measurement techniques: DXA and Archimedes' principle.

The standard method for determination of density (g/cm3) of bones from small animals has been the application of Archimedes' principle. A recent development has been software for the determination of "density" (g/cm2) of small animal bones with dual-energy X-ray absorptiometry (DXA). We compared Archimedes' principle and DXA (Hologic QDR-2000) in the measurement of the densities of whole and hollowed femurs of 5- to 6-month-old retired female breeder rats. In an attempt to ensure detectable treatment differences, rats were used from a low-vitamin D Holtzman and a supplemental-vitamin D Sprague-Dawley colony. Whole femur densities were higher for supplemental-vitamin D colony rats than for low vitamin D rats using both techniques (Archimedes' principle, p < 0.002; DXA, p < 0.005), and the densities from the two techniques were highly correlated (r = 0.82, p < 0.0001). Actual density values were higher for Archimedes' principle than for DXA. Other variables such as femur ash weight and calcium content were also highly correlated to densities with both techniques. Hollowed femur density values were higher than whole femur values with Archimedes' principle but lower with DXA. Colony effects for hollowed femur densities were diminished with Archimedes' principle (p < 0.03) and eliminated with DXA (p < 0.53). Investigation of whole bones is more biologically relevant, and both techniques were effective in detecting differences between whole femurs from low-vitamin D and supplemental-vitamin D colony rats.

A paradigm of experimentally induced mild hyperthyroidism: effects on nitrogen balance, body composition, and energy expenditure in healthy young men.

Although T3 exerts major regulatory actions in both animals and humans, most clinical studies of T3 administration have been relatively short term. The present study examined the effects of more than 2 months (63 days) of low dose T3 treatment on nitrogen balance, body composition, 24-h energy expenditure (EE), and protein turnover in seven healthy men studied at an in-patient metabolic unit. Subjects were also randomly assigned to either high or low fat diets to determine the effects of diet composition. T3 treatment produced significant losses in both lean mass (1.5 +/- 0.3 kg) and fat mass (2.7 +/- 0.4 kg) by 6 weeks, with similar reductions in both at 9 weeks. The high fat diet somewhat attenuated the loss of body fat. Nitrogen balance was significantly negative for the first 3 weeks of T3 treatment, but tended to return to baseline thereafter. There were no significant effects of treatment on protein turnover at 9 weeks, although there was a slight increase in leucine oxidation (P = 0.07). Despite the apparent adaptation in nitrogen balance, total 24-h EE and sleeping EE were significantly increased at 9 weeks. We conclude that although healthy men are able to adapt to mild hyperthyroidism in terms of nitrogen balance, they exhibit significant and persistent changes in fat and fat-free mass as well as energy balance.

Role of energy expenditure in the development of pediatric obesity.

The role that energy expenditure plays in pediatric obesity was somewhat confused by early research purporting to show that, as a group, obese children have lower energy intakes than do lean children. On the basis of this intake data, the conclusion was drawn that obese persons are somehow energy efficient, leading to weight gain. More recent research examining energy expenditure has shown clearly that, as a group, obese children have higher energy expenditures than do their lean counterparts. With the advent of the doubly labeled water method for determining free-living energy expenditure, it has been shown that obese children underreport intake significantly more than do lean children. When measurements are properly adjusted for differences in body size, there are generally no major differences in energy expenditure between lean and obese groups. However, in some cross-sectional studies, a low level of physical activity has been shown to be related to current body fatness. In addition, longitudinal studies have shown that a low level of energy expenditure, particularly energy expended in physical activity, is associated with both body fatness and weight gain.

Supplementation frequency and ascorbic acid status in adult males.

This study was performed to determine if experimental subjects given ascorbic acid (AA) in a 240-mg dose every 4 days maintain blood levels of AA similar to levels of control subjects given 20 mg three times per day. All subjects ingested foods providing 6 to 7 mg AA/day but adequate in other nutrients. Mean serum AA for all subjects was 1.26 mg/dl initially indicating a habitual AA intake of over 100 mg/day. After 32 days on 66 mg AA/day, mean serum AA of control subjects remained below 0.7 mg/dl. After the first depletion period experimental subjects had significantly lower (p less than 0.05) serum AA than control subjects (0.74 versus 1.02 mg/dl). By the third depletion period experimental subjects adjusted to the less frequent dosage such that serum levels of AA were not lower. They were sometimes significantly higher (p less than 0.05) 1 day after the 240-mg dose. Experimental subjects had similar or higher mean white blood cell AA throughout the experiment. White blood cell AA was significantly (p less than 0.05) and negatively correlated with white blood cell count (r = -0.65) Results suggest that subjects adjust to receiving supplements of AA on a periodic basis at least under the conditions imposed in this study.

Differential oxidation of individual dietary fatty acids in humans.

BACKGROUND: Dietary fatty acids that are more prone to oxidation than to storage may be less likely to lead to obesity. OBJECTIVE: The aim of this study was to determine the effect of chain length, degree of unsaturation, and stereoisomeric effects of unsaturation on the oxidation of individual fatty acids in normal-weight men. DESIGN: Fatty acid oxidation was examined in men consuming a weight-maintenance diet containing 40% of energy as fat. After consuming the diet for 1 wk, subjects were fed fatty acids labeled with (13)C in the methyl or carboxyl position (10 mg/kg body wt). The fatty acids fed in random order were laurate, palmitate, stearate, oleate, elaidate (the trans isomer of oleate), linoleate, and linolenate blended in a hot liquid meal. Breath samples were collected for the next 9 h and the oxidation of each fatty acid was assessed by examining liberated (13)CO(2) in breath. RESULTS: Cumulative oxidation over the 9-h test ranged from a high of 41% of the dose for laurate to a low of 13% of the dose for stearate. Of the 18-carbon fatty acids, linolenate was the most highly oxidized and linoleate appeared to be somewhat conserved. (13)C recovery in breath from the methyl-labeled fatty acids was approximately 30% less than that from the carboxyl-labeled fatty acids. CONCLUSIONS: In summary, lauric acid is highly oxidized, whereas the polyunsaturated and monounsaturated fatty acids are fairly well oxidized. Oxidation of the long-chain, saturated fatty acids decreases with increasing carbon number.

Effects of fish oil on serum lipids in men during a controlled feeding trial.

Effects of fish-oil (FO) feeding on serum lipids were investigated in a 42-d controlled diet study. Fifteen healthy male college students were assigned to one of three groups: control (0 g FO); 5 g FO, supplying 2 g n - 3 (omega-3) fatty acids (FAs); or 20 g FO, supplying 8 g n - 3 FAs. In an initial 7-d period subjects consumed a basal diet with no FO. Then FO replaced an equivalent amount of margarine for 5 wk. FO feeding significantly (p less than 0.05) decreased the serum n - 6 FAs, linoleic acid, eicosatrienoic acid, and arachidonic acid. A significant increase in the n - 3 FAs, eicosapentaenoic acid and docosahexaenoic acid, was noted in serum, platelet, and neutrophil phospholipids. The 20-g-FO group showed a 30% decrease (p less than 0.01) in triglycerides after 2 wk FO with no further decrease observed. Thus, 20 g FO produced changes in both FA patterns and triglyceride concentrations whereas 5 g FO produced changes in FA patterns only. Neither FO amount resulted in significant changes in total or HDL cholesterol, apolipoprotein A-I, or apolipoprotein B-100.

Evaluation of body fat in fatter and leaner 10-y-old African American and white children: the Baton Rouge Children's Study.

BACKGROUND: Only a few published studies in children used several methods to compare body fat in large groups of fatter and leaner multiethnic children. We hypothesized that the preferred methods of determining body fat may differ in children with larger compared with smaller amounts of body fat, in boys compared with girls, and in African Americans compared with whites. OBJECTIVE: Our objective was to evaluate several methods of predicting body fat in 10-12-y-old white and African American boys and girls. DESIGN: The body fat of 129 African American and white boys and girls aged 10-12 y, distributed equally by sex and race, was measured with use of dual-energy X-ray absorptiometry (DXA), underwater weighing (densitometry), isotope dilution (H(2)18O), bioelectrical impedance, skinfold thicknesses, corporal diameters, and circumferences. RESULTS: With use of DXA as the criterion variable, body fat was bimodally distributed in the boys and skewed to higher values in the girls. Biceps skinfold thickness had the highest predictive value of any single skinfold thickness compared with DXA fat. All formulas for estimating body fat from skinfold thicknesses, body density, or impedance performed better in the children in the upper one-half of the fat distribution (the fatter children) than in those in the lower one-half (the leaner children). Body mass index was highly correlated with body fat (R2 = 0.77); there was a good correlation for the fatter children (R2 = 0.66) and no correlation for the leaner children (R2 = 0.09). The hydration of the fat-free mass was significantly higher in the fatter children than in the leaner ones (79.2% compared with 76.7%). CONCLUSIONS: These data are consistent with the hypothesis that all methods of estimating body fat work better in children with larger amounts of body fat. The best formulas use skinfold thicknesses, bioelectrical impedance, and a 4-compartment model.

Energy expenditure.

Although human energy expenditure has been studied for over 100 years, many unanswered questions remain regarding the role that individual components of energy expenditure have in the etiology of obesity. Most techniques for measuring physical activity, the most variable component of TDEE, are less than adequate, and differences in energy metabolism are difficult to detect in a static comparison. When energy expenditure is examined in obese and lean subjects at one point in time, there frequently are no differences in energy expenditure when appropriately normalized. However, when subjects are studied longitudinally or when the system is perturbed (such as overfeeding or exercising), differences can be observed. Using a combination of the techniques available today, each component can be reliably studied, and the role that each has in the development of obesity can be ascertained.

Long-term calorie restriction reduces energy expenditure in aging monkeys.

Calorie restriction to produce stable long-term adult body weight for approximately 10 years prevents obesity and diabetes in middle-aged rhesus monkeys. To determine whether this dietary regimen also alters energy metabolism, the doubly labeled water method was used to measure total daily energy expenditure. Six adult male rhesus monkeys, which had been calorie-restricted for more than 10 years, were compared to 8 control adult monkeys, which had been fed ad libitum for their entire lives. The calorie-restricted monkeys weighed less than the ad-libitum fed monkeys and had a lower lean body mass and lower fat mass. Total daily energy expenditure was lower in the calorie-restricted than in the ad-libitum fed monkeys, even when corrected for differences in body size using body weight (563 +/- 64 vs 780 +/- 53 kcal/d; p < .04), surface area (547 +/- 67 vs 793 +/- 56 kcal/d; p < .05), or lean body mass (535 +/- 66 vs 801 +/- 54 kcal/d; p < .02) as covariates. Thyroxine (T4) was reduced and the free thyroxine index was suggestively lower in the calorie-restricted monkeys whereas triiodothyronine (T3) was not significantly different. Activity in calorie-restricted monkeys was similar to that of a weight-matched younger adult comparison group. We conclude that the process of preventing obesity by long-term caloric restriction causes a significant and sustained long-term reduction in energy expenditure, even when corrected for lean body mass.

Relationship between resting metabolic rate and the composition of the fat-free mass.

Although a low resting metabolic rate (RMR) has been shown to be a risk factor for future weight gain, little is known about the mechanisms determining its level. We tested the hypothesis that the composition of the fat-free mass (FFM) is a main determinant of RMR. If this hypothesis is true, a regression model including internal organ masses as independent variables should explain a larger fraction of the variance in RMR than is explained using only FFM as a predictor. We measured fat mass by hydrodensitometry, liver and kidney volumes by computed tomography (CT), heart mass by echocardiography, muscle mass by dual-energy x-ray absorptiometry (DEXA), and RMR by calorimetry in 40 subjects. FFM and fat mass explained 83% of the variability in RMR (standard error of the estimate [SEE], 420 kJ/d) in a multiple regression analysis. Combinations of organ and muscle masses performed as well as but not better than stepwise multiple regression models. The fact that the composition of the lean mass could not improve the prediction of RMR in comparison to the traditional FFM-fat mass model suggests that the weight of internal organs is not a main determinant of RMR. This may indicate that the variability in RMR is associated with variation in energy expenditure per kilogram of tissue of the individual organs.

Relationship of dietary fat and serum cholesterol ester and phospholipid fatty acids to markers of insulin resistance in men and women with a range of glucose tolerance.

High-fat diets are associated with insulin resistance, however, this effect may vary depending on the type of fat consumed. The purpose of this study was to determine the relationship between intakes of specific dietary fatty acids (assessed by 3-day diet records and fatty acid composition of serum cholesterol esters [CEs] and phospholipids [PLs]) and glucose and insulin concentrations during an oral glucose tolerance test (OGTT). Nineteen men and 19 women completed the study. Nine subjects had type 2 diabetes or impaired glucose tolerance. Fasting insulin correlated with reported intakes of total fat (r = .50, P < .01), monounsaturated fat (r = .44, P < .01), and saturated fat (r = .49, P < .01), but not with trans fatty acid intake (r = .11, not significant [NS]). Fasting glucose also correlated with total (r = .39, P < .05) and monounsaturated fat intakes (r = .37, P < .05). In multivariate analysis, both total and saturated fat intake were strong single predictors of fasting insulin (R2 approximately .25), and a model combining dietary and anthropometric measures accounted for 47% of the variance in fasting insulin. Significant relationships were observed between fasting insulin and the serum CE enrichments of myristic (C14:0), palmitoleic (C16:1), and dihomo-gamma-linolenic (C20:3n-6) acids. In multivariate analysis, a model containing CE 14:0 and percent body fat explained 45% of the variance in fasting insulin, and C14:0 and age explained 30% of the variance in fasting glucose. PL C20:3n-6 explained 30% of the variance in fasting insulin, and a model including PL C18:1n-11 cis, C20:3n-6, age and body fat had an R2 of .58. In conclusion, self-reported intake of saturated and monounsaturated fats, but not trans fatty acids, are associated with markers of insulin resistance. Furthermore, enhancement of dihomo-gamma-linolenic and myristic acids in serum CE and PL, presumably markers for dietary intake, predicted insulin resistance.

Field use of D2 18O to measure energy expenditure of soldiers at different energy intakes.

To test the application of doubly labeled water under adverse field conditions, energy expenditures of 16 special operations soldiers were measured during a 28-day field training exercise. Subjects were matched by fat-free mass and divided equally between an ad libitum ready-to-eat meal diet and a 2,000 kcal/day lightweight ration. Subjects recorded intakes daily, and body composition was measured before and after the exercise. At the beginning of the study, subjects moved to a new northerly location and, therefore, a new water supply. To compensate for this, a group of soldiers who did not receive heavy water was followed to measure isotopic base-line changes. Energy expenditure by doubly labeled water was in agreement with intake/balance (3,400 +/- 260 vs. 3,230 +/- 520 kcal/day). The overall coefficient of variation of energy expenditure by doubly labeled water was half that of intake/balance (7.6 vs. 16.1%). The coefficient of variation of repeat measures with doubly labeled water was 7.3%. Energy expenditure of the ready-to-eat meal group, 3,540 +/- 180 kcal/day, was not significantly different from the lightweight ration group, 3,330 +/- 301 kcal/day. Doubly labeled water was valid under field conditions.

Assessment of energy intake underreporting by doubly labeled water and observations on reported nutrient intakes in children.

OBJECTIVE: To compare reported energy intake with energy expenditure using doubly labeled water (DLW). Additionally, we compared reported nutrient intakes of our subject population with national survey population data from the third National Health and Nutrition Examination Survey (NHANES III). DESIGN: This was a cross-sectional study of children, balanced by race and gender, primarily characterized by 4 body types: lean, obese, centrally fat, or peripherally fat. SUBJECTS/SETTING: Children (n=118; mean age=10 years) kept 8-day food records, with nutritionists recording weekday school lunch intakes. These subjects, assisted by their parents, recorded all breakfasts, dinners, snacks, and weekend lunches. STATISTICAL ANALYSES PERFORMED: Data were analyzed using least squares analysis of variance with the general linear models procedure. Tukey's test was used for multiple comparisons of predicted treatment means. RESULTS: Mean daily energy intake was underreported by 17% to 33% of energy expenditure. The tendency to underreport increased with age. Underreporting occurred in all groups and subgroups studied. Reported mean intakes of vitamin A, vitamin E, vitamin B-6, calcium, zinc, and copper were less than 70% of the Recommended Dietary Allowance (RDA) for African-American girls, whereas African-American boys reported similarly low intakes of copper. On average, white girls reported intakes less than 70% of the RDA for zinc and copper, whereas white boys reported low intakes of copper (60% of the RDA). Reported intakes in general were somewhat lower than those reported in NHANES III. APPLICATIONS/CONCLUSIONS: Dietetics professionals may modify the nutritional advice they give to patients/subjects based on food intake records and other data. For children, particularly, it is imperative that ethnic and gender differences be taken into consideration and that all foods eaten be accounted for as much as possible.

Selenium content of foods purchased or produced in Ohio.

Approximately 450 samples of about 100 types of foods consumed by rural and urban Ohioans were analyzed for selenium. Meat, dairy products, eggs, and grain products produced in Ohio have considerably lower selenium content than corresponding products produced in high selenium areas, such as South Dakota. Retail Ohio foods with interregional distribution tended to be higher in selenium content than corresponding foods produced in Ohio. Best sources of selenium in Ohio foods commonly consumed were meat and pasta products. Poor sources of selenium were fruits, most vegetables, candies, sweeteners, and alcoholic and nonalcoholic beverages. Establishment of an accurate data base for selenium depends on knowledge of the interregional distribution of foods, the selenium content of foods at their production site, and the selenium content of foods with wide local distribution.

Validity of self-reported energy intake in lean and obese young women, using two nutrient databases, compared with total energy expenditure assessed by doubly labeled water.

OBJECTIVE: To compare self-reported total energy intake (TEI) estimated using two databases with total energy expenditure (TEE) measured by doubly labeled water in physically active lean and sedentary obese young women, and to compare reporting accuracy between the two subject groups. DESIGN: A cross-sectional study in which dietary intakes of women trained in diet-recording procedures were analyzed using the Minnesota Nutrition Data System (NDS; versions 2.4/6A/21, 2.6/6A/23 and 2.6/8.A/23) and Nutritionist III (N3; version 7.0) software. Reporting accuracy was determined by comparison of average TEI assessed by an 8 day estimated diet record with average TEE for the same period. RESULTS: Reported TEI differed from TEE for both groups irrespective of nutrient database (P<0.01). Measured TEE was 11.10+/-2.54 and 11.96+/-1.21 MJ for lean and obese subjects, respectively. Reported TEI, using either database, did not differ between groups. For lean women, TEI calculated by NDS was 7.66+/-1.73 MJ and by N3 was 8.44+/-1.59 MJ. Corresponding TEI for obese women were 7.46+/-2.17 MJ from NDS and 7.34+/-2.27 MJ from N3. Lean women under-reported by 23% (N3) and 30% (NDS), and obese women under-reported by 39% (N3) and 38% (NDS). Regardless of database, lean women reported higher carbohydrate intakes, and obese women reported higher total fat and individual fatty acid intakes. Higher energy intakes from mono- and polyunsaturated fatty acids were estimated by NDS than by N3 in both groups of women (P< or =0.05). CONCLUSIONS: Both physically active lean and sedentary obese women under-reported TEI regardless of database, although the magnitude of under-reporting may be influenced by the database for the lean women. SPONSORSHIP: USDA Hatch Project award (ARZT-136528-H-23-111) to LB Houtkooper and WH Howell.

Effect of moderate to very low fat defined formula diets on serum lipids in healthy subjects.

Serum total cholesterol, high density lipoprotein (HDL) cholesterol, and triglyceride levels were studied in healthy male and female subjects consuming for one-week periods a diet of conventional food (CF) providing 42% of energy as fat, principally butter fat, and then in random order nutritionally complete, defined formula diets of moderate (32%) to very low (1%) fat content. Compared to CF, the formula with 32% of energy as corn oil lowered serum cholesterol by 25% and the ratio of total to HDL-cholesterol by 13%. Low (9%) and very low (1-3%) fat formulas reduced HDL-cholesterol by as much as 40%, raised the total:HDL-cholesterol ratio by about 20% and raised serum triglyceride levels by as much as 100%. When low and very low fat formulas were ingested for three weeks, these effects persisted although maximal responses occurred during the first week. These results demonstrated that a moderate fat formula diet with a high P/S ratio had a more favorable effect on serum lipid levels than various low fat formulas. Low fat conventional food diets should be studied in long-term controlled metabolic experiments before such diets are recommended to the general population for coronary heart disease or cancer prevention.

The effect of an herbal dietary supplement containing ephedrine and caffeine on oxygen consumption in humans.

OBJECTIVE: To determine if an herbal dietary supplement for weight loss increases metabolism. DESIGN: Measurement of peak oxygen consumption in response to the supplement followed by a double-blind placebo-controlled crossover measurement of oxygen consumption in response to the supplement. SETTING: The study was conducted in an academic research clinic. SUBJECTS: Ten obese females (aged 41 +/- 4 years [body mass index (BMI)] 33.3 +/- 2.6 kg/m2) participated in the peak oxygen consumption test; six of these females participated in the crossover trial. INTERVENTIONS AND OUTCOME MEASURES: Peak oxygen consumption was measured for 45 minutes after taking two herbal dietary supplement capsules orally, each containing the equivalent of 10 mg of caffeine and 5 mg of ephedrine. The crossover trial measured oxygen consumption for 45 minutes after taking two herbal dietary supplement capsules or two placebo capsules orally. RESULTS: The herbal dietary supplement increased peak oxygen consumption 0.178 +/- 0.03 (SEM) kcal/min (8.01 +/- 1.35 kcal/min expressed over 45 minutes) above baseline (p < 0.0001), and 2.0 +/- 0.56 kcal/min over 45 minutes compared to placebo (p < 0.006). CONCLUSIONS: The herbal dietary supplement increased oxygen consumption when taken according to the package directions. The significance of this rise for weight loss requires further research.