['Involuntary weight loss affects 20% of community dwelling older adults. The underlying mechanism for this disorder is unknown. Objective is to determine if failure of older persons to regain weight is associated with elevated pro-inflammatory cytokine and leptin levels.', 'Prospective diet intervention study.', 'University of Washington Medical Center from 2001-2005.', 'Twenty-one younger (18-35 years old) and nineteen older (>or= 70 years old) men and women.', 'Each subject was placed for two weeks on a weight-maintaining diet, followed in sequence by 2 weeks of 30% caloric restriction, then 4 weeks of ad libitum food intake.', 'Plasma leptin levels, fasting serum pro-inflammatory cytokine levels, and peripheral blood mononuclear cell cytokine levels were measured.', 'Leptin levels in the two cohorts decreased after caloric restriction and increased after ad-libitum food consumption resumed. Plasma TNF alpha levels were higher in older subjects compared to younger adults. However, there was no association between changes in TNF alpha levels and changes in AUC leptin.'] Do leptin levels recover normally in healthy older adults after acute diet-induced weight loss?