OBJECTIVE To evaluate whether weight cycling is detrimental to the changes in glucose tolerance in obese individuals without overt NIDDM and related to the amplitude of weight cycling. METHODS Historical prospective observational study of a hospital-based cohort. METHODS One hundred twenty-five obese individuals drawn from the medical records of the Hospital of Endocrinology, University of Tartu, in whom at least one weight cycle was detected. Selected cutoff value for weight cycling set to 3, 6, 9 and 12 kg of weight loss and subsequent regain. METHODS Weight measurements and oral glucose tolerance tests. The latest oral glucose tolerance test and the one during the first visit compared by the 2 h blood glucose values and areas under the blood glucose curve. RESULTS No deterioration of glucose tolerance recorded in any of the groups with different cutoff values for weight cycling. No trend towards the deterioration of glucose tolerance with increasing amplitude of weight cycles. CONCLUSIONS We cannot claim that weight cycling is detrimental to glucose tolerance in non-diabetic obese individuals. This effect is independent of the amplitude of weight cycling. Weight reduction may be recommended to obese individuals for the prevention of NIDDM even if it is unsuccessful and the phenomenon of weight cycling results.