We examined if 12 weeks of capsaicinoid (CAP) supplementation affected appetite, body composition and metabolic health markers. Seventy seven healthy male and female volunteers (30 +/- 1 y, 171.2 +/- 9.8 cm, 81.0 +/- 2.2 kg, 27.5 +/- 0.6 kg/m(2)) were randomly assigned to ingest either low-dose CAP (2 mg/d; L-CAP, n = 27), high-dose CAP (4 mg/d; H-CAP, n = 22) from Capsimax or placebo (corn starch; PLA, n = 28) for 12 weeks. At baseline (0 WK), 6 weeks (6 WK) and 12 weeks (12 WK) waist: hip ratio, body composition via dual energy x-ray absorptiometry (DEXA, 0 WK and 12 WK only), self-reported Calorie intakes, appetite levels via Council on Nutrition Appetite Questionnaire (CNAQ) and serum metabolic health markers (0 WK and 12 WK only) were analyzed. Moreover, an oral glucose tolerance test (OGTT) was administered at 0 WK and 12 WK, and serum glucose and insulin responses were examined 30-120 min post test-drink consumption. Waist: hip ratio significantly decreased in L-CAP from 0 WK to 6 WK (p < 0.05), although supplementation did not significantly affect body composition. H-CAP consumed less kcal/d compared to PLA at 12 WK (difference = 257 kcal/d, p < 0.05) and L-CAP participants at 12 WK (difference = 247, p < 0.05). Twenty-three percent (9/39) of the originally-enrolled H-CAP participants reported GI distress, although no participants in the L-CAP group reported such adverse events. Interestingly, H-CAP participants presented significant increases in serum insulin as well as significant decreases in serum HDL cholesterol levels from WK0 to WK12. However, supplementation did not affect the insulin response to the administered OGTT and/or other indices of insulin sensitivity. These data suggest that H-CAP supplementation reduces self-reported energy intake after 12 weeks of supplementation, and L-CAP supplementation also reduces waist: hip ratio. Longer-term effects of capsaicinoid supplementation on basal insulin and cholesterol levels warrant further investigation. (C) 2017 The Authors. Published by Elsevier Ltd.