Objective: Restrained eating is a common dietary practice among individuals who are attempting to prevent weight gain, but little is known about differences in energy physiology and regulation between restrained and unrestrained eaters. We investigated this issue in non-obese free-living postmenopausal women classified as long-term restrained (n=26) or unrestrained (n=34) eaters group matched for body mass index (BMI).
Measurements: Measurements were made of total energy expenditure (TEE), resting energy expenditure (REE), body composition, reported leisure time activity, maximal aerobic capacity (VO2max) and weight change during the study period. In addition, physical activity level (PAL) and nonexercise activity thermogenesis (NEAT) were calculated from measured variables.
Results: There were no significant differences between the groups in body composition, weight change, aerobic capacity or total leisure time activity. Relationships between fat-free mass (FFM) and both REE and TEE, and the relationship between work load and energy expenditure in the test of maximal oxygen consumption, were also not different between groups. However, restrained eaters had a significantly lower PAL (equal to TEE/REE, 1.72+/-0.04 vs 1.84+/-0.04, P<0.05). In addition, in multiple regression models predicting NEAT, NEAT was significantly lower in restrained eaters than unrestrained eaters and there was a positive relationship between NEAT and weight change in unrestrained eaters but no relationship in restrained eaters (P<0.05).
Conclusions: In contrast to a previous report, we found no significant difference in TEE between restrained and unrestrained eaters. PAL was slightly lower in restrained eaters, apparently due to reduced NEAT, and restrained eaters also lacked the positive association between NEAT and body weight change seen in unrestrained eaters. This latter finding, if confirmed in future studies, could help explain an increased susceptibility of restrained eaters to weight gain.
Sponsorship: NIH grants AG12829, DK46124 and T32AG00209, and US Cooperative Agreement number 58-1950-9-001.