Hypogonadism in males is associated with increased body fat and altered postprandial metabolism, but mechanisms remain poorly understood. Using a cross-over study design, we investigated the effects of short-term sex hormone suppression with or without testosterone add-back on postprandial metabolism and the fate of dietary fat. Eleven healthy males (age: 29 ± 4.5 year; BMI: 26.3 ± 2.1 kg/m2 ) completed two 7-day study phases during which hormone levels were altered pharmacologically to produce a low sex hormone condition (gonadotropin releasing hormone antagonist, aromatase inhibitor, and placebo gel) or a testosterone add-back condition (testosterone gel). Following 7 days of therapy, subjects were administered an inpatient test meal containing 50 μCi of [1-14 C] oleic acid. Plasma samples were collected hourly for 5 h to assess postprandial responses. Energy metabolism (indirect calorimetry) and dietary fat oxidation (14 CO2 in breath) were assessed at 1, 3, 5, 13.5, and 24 h following the test meal. Abdominal and femoral adipose biopsies were taken 24 h after the test meal to determine uptake of the labeled lipid. Postprandial glucose, insulin, free-fatty acid, and triglyceride responses were not different between conditions (P > 0.05). Whole-body energy metabolism was also not different between conditions at any time point (P > 0.05). Dietary fat oxidation trended lower (P = 0.12) and the relative uptake of 14 C labeled lipid into femoral adipose tissue was greater (P = 0.03) in the low hormone condition. Short-term hormone suppression did not affect energy expenditure or postprandial metabolism, but contributed to greater relative storage of dietary fat in the femoral depot. ClinicalTrials.gov Identifier: NCT03289559.
Keywords: Energy metabolism; hypogonadism; lipid metabolism; postprandial metabolism; testosterone.
© 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.