The medical effects of modest weight reduction (approximately 10% or less) in patients with obesity-associated medical complications were reviewed. The National Library of Medicine MEDLINE database and the Derwent RINGDOC database were searched to identify English language studies that examined the effects of weight loss in obese patients with serious medical complications commonly associated with obesity (non-insulin dependent diabetes mellitus (NIDDM or type II), hypertension, hyperlipidemia, hypercholesterolemia, and cardiovascular disease). Studies in which patients experienced approximately 10% or less weight reduction were selected for review. Studies indicated that, for obese patients with NIDDM, hypertension or hyperlipidemia, modest weight reduction appeared to improve glycemic control, reduce blood pressure, and reduce cholesterol levels, respectively. Modest weight reduction also appeared to increase longevity in obese individuals. In conclusion, a large proportion of obese individuals with NIDDM, hypertension, and hyperlipidemia experienced positive health benefits with modest weight loss. For patients who are unable to attain and maintain substantial weight reduction, modest weight loss should be recommended; even a small amount of weight loss appears to benefit a substantial subset of obese patients.