Ninety-five studies conducted between September 1955 and October 1983 measuring changes in human serum lipid and lipoprotein levels in response to exercise training were analyzed using meta-analysis. Change in body weight during exercise training may confound observed serum lipid and lipoprotein level changes; thus, data from these studies were partitioned into those where subjects gained body weight, maintained body weight, or lost body weight. Results showed differential changes in cholesterol, triglycer- ide, low-density lipoprotein-cholesterol (LDL-C), high-density lipoprotein\x=req-\ cholesterol, and cholesterol/high-density lipoprotein-cholesterol levels in the three body-weight categories. Where body weight did not change, cholesterol and LDL-C levels decreased significantly (7.3 mg/dL and 3.3 mg/dL, respectively). Where body weight decreased, cholesterol and LDL-C levels also decreased significantly (13.2 mg/dL and 11.1 mg/dL, respective- ly). However, with body-weight increase, cholesterol and LDL-C levels increased by 2.9 mg/dL and 3.0 mg/dL, respectively. These results suggest that reductions in cholesterol and LDL-C levels were greatest when exercise training was combined with body-weight losses. (JAMA 1985;254:919-924)