Effects of intentional weight cycling on non-obese young women.

This study investigated the effects of intentional weight cycling in non-obese, young women (n = 5; mean age, 24.6 years; mean body mass index [BMI], 20.5 kg/m(2)). During the first 30 days, the subjects lost more than 4 kg with energy restriction alone (first diet period). In the following 14 days, they regained more than the weight they had lost by eating ad libitum (free-living period). In the subsequent 30 days, they once again lost more than 4 kg with only energy restriction (second diet period). Height, weight, waist and hip circumferences, body composition, lipid profiles, thyroid hormones, systolic and diastolic blood pressures (SBP, DBP), and resting energy expenditure (REE) were examined. Measurements were taken at the beginning of the study (day 0), at the end of each diet period (day 30 and day 74), the end of the free-living period (day 44), and on day 180. The mean change in each variable from baseline (day 0) was used and controlled for the baseline value, baseline weight, and change in weight (Delta weight). Statistical tests were performed to determine the significance of the mean changes in the variables. By day 180, there were significant decreases in the subjects' lean body mass (P <.01), serum triiodothyronine (T(3)) (P <.001), serum total thyroxine (T(4)) (P <.001), and REE (P <.001), and significant elevations of SBP (P <.05) and DBP (P <.001). The lipid profiles had not changed except for increased triglycerides (TG). These results suggest that weight cycling through energy restriction alone may have negative health consequences in non-obese, young women. Copyright 2002 by W.B. Saunders Company