This study examined the relationships among body fat, diet composition, energy intake, and exercise in adults. Male (n = 107) and female (n = 109) adults aged 18-71 y (36.6 +/- 1.0 y, means +/- SEM) were hydrostatically weighed to determine body fat (5.7-49.0% of total weight). Diet and exercise behaviors were determined by use of a questionnaire. As body fat increased, percent of energy intake derived from fat increased (p less than 0.001) whereas the percent from carbohydrate decreased (p less than 0.001). There was no relationship between energy intake and adiposity although leanness and exercise were related (p less than 0.001). When subgroups of lean and obese subjects were compared, the lean subjects derived approximately 29% of their energy from fat and 53% from carbohydrate vs 35% and 46%, respectively, for the obese subjects. No differences were found between groups for energy intake but the lean individuals exercised more often than did the obese individuals. These data suggest that diet composition may play as important a role in fat deposition as do energy intake and lack of exercise.

Health care professionals have used restrictive dieting and exercise intervention strategies in an effort to combat the rising prevalence of obesity in affluent countries. In spite of these efforts, the prevalence of obesity continues to rise. This apparent ineffectiveness of diet and exercise programming to reduce obesity has caused many health care providers, obesity researchers, and lay persons to challenge the further use of diet and exercise for the sole purpose of reducing body weight in the obese. The purposes of this paper were to examine the history and effectiveness of diet and exercise in obesity therapy and to determine the best future approach for health promotion in the obese population. A brief survey of the most popular dieting techniques used over the past 40 yr shows that most techniques cycle in and out of popularity and that many of these techniques may be hazardous to health. Data from the scientific community indicate that a 15-wk diet or diet plus exercise program produces a weight loss of about 11 kg with a 60-80% maintenance after 1 yr. Although long-term follow-up data are meager, the data that do exist suggest almost complete relapse after 3-5 yr. The paucity of data provided by the weight-loss industry has been inadequate or inconclusive. Those who challenge the use of diet and exercise solely for weight control purposes base their position on the absence of weight-loss effectiveness data and on the presence of harmful effects of restrictive dieting. Any intervention strategy for the obese should be one that would promote the development of a healthy lifestyle. The outcome parameters used to evaluate the success of such an intervention should be specific to chronic disease risk and symptomatologies and not limited to medically ambiguous variables like body weight or body composition.

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The primary purpose of this investigation was to compare estimations of percentage body fat (%fat) using air displacement plethysmography (ADP) and hydrostatic weighing (HW) in a heterogeneous (age and %fat) sample of the population. Of secondary importance was to determine whether there were differences between the two methods among lean (n = 32), average (n = 34) and overweight (n = 29) subsets of this sample. A total of 95 adults (men 27, women 68) ranging in age from 18-52 years volunteered for this study. Test-retest reliability for %fat ADP (n = 16) was 0.99 with a technical error of 0.75%fat and a coefficient of variation of 3.4%fat. Mean body density using ADP [1.048 (SD 0.016) g.ml-1] was not significantly different when compared to HW [1.049 (SD 0.017) g.ml-1], which corresponded to a non-significant difference in %fat [22.5 (SD 7.3)% ADP compared to 22.0 (SD 7.6)% HW]. Regression analysis provided the equation: %fat HW = 0.9121%fat ADP + 1.5123; r = 0.88, SEE = 3.6, which did not differ significantly from the line of identity. Data for the subsets revealed a significant overestimation of %fat ADP [16.4 (SD 4.8)%] compared to HW [14.1 (SD 3.2)%] (P = 0.001) for lean individuals while no difference was found in the average [21.9 (SD 4.4)%fat ADP compared to 22.0 (SD 3.4)%fat HW] or overweight [29.9 (SD 5.5)%fat ADP compared to 30.8 (SD 4.1)%fat HW] subsets. Measuring %fat by ADP is a highly reliable method and valid when compared to HW for a heterogeneous sample of adults. The ADP method requires little expertise to operate, is quick to perform, and may be more accommodating for certain individuals compared to HW. However, in this study ADP was less valid for lean individuals. Further investigation is warranted to determine the bias of this method for subsets of the population which may be outside the average range of %fat (men 15.4%-22.0%, women 18.4%-28.5%).

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We performed a randomized exercise training study to assess the effects of traditional Nautilus-style (TR) or superslow (SS) strength training on muscular strength, body composition, aerobic capacity, and cardiovascular endurance. Subjects were 14 healthy, sedentary women, 19-45 years of age (mean +/- SD age, 32.7 +/- 8.9 years), randomized to either the SS or TR training protocols and trained 3 times per week for 10 weeks. Measurements were taken both before and after training, which included a maximal incremental exercise test on a cycle ergometer, body composition, and 1 repetition maximum (1RM) tests on 8 Nautilus machines. Both groups increased their strength significantly on all 8 exercises, whereas the TR group increased significantly more than the SS group on bench press (34% vs. 11%), torso arm (anterior lateral pull-down) (27% vs. 12%), leg press (33% vs. 7%), leg extension (56% vs. 24%), and leg curl (40% vs. 15%). Thus, the TR group's improvement in total exercise weight lifted was significantly greater than that of the SS group after testing (39% vs. 15%). Exercise duration on the cycle ergometer and work rate significantly improved for both groups, but there was no group-by-training interaction. No significant differences were found for body composition or additional aerobic variables measured. Both strength training protocols produced a significant improvement in strength during a 10-week training period, but the TR protocol produced better gains in the absence of changes in percentage of body fat, body mass index, lean body mass, and body weight. In addition, strength training alone did not improve Vo2max, yet short-term endurance increased.

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