Effects of Severe Dietary Restriction on Male Reproductive Hormones*

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Abstract
The reproductive hormone response to severe caloric restriction (600 Cal day−1) was studied in six men 33–67% over ideal body weight who completed a 32-day protocol consisting of three periods in the following order: control (4 days), maintenance protein and energy; diet A (14 days), 50 g lean beef protein plus 50 g casein; and diet B (14 days), 50 g lean beef protein plus 50 g carbohydrate. Weight loss (8.7–12.5 kg) was associated with a decrease in mean blood glucose [4.52 ± 0.60 (±SEM), 3.49 ± 0.29, and 3.80 ± 0.30 mM] and an increase in /3–hydroxybutyrate (−1 for 4 h (expressed as milliinternational units perml area under the concentration-time curve) were: FSH, 1558 ± 359,1336 ± 545, and 1337 ±321 (P = NS); and LH, 1730 ± 545, 1612 ± 481, and 1782 ± 556 (P = NS), respectively. Basal serum FSH, LH, free testosterone (T), and total T changed, while 24-h urinary LH and FSH excretion increased on diet A only. Unlike 10 days of total fasting, during whichthe same amount of weight was lost, basal serum FSH and LHRH-stimulated serum FSH responses were both significantly diminished by 25%, and serum T was diminished by 19% (1), these same parameters were little changed by either low energy diet. Theincreased urinary excretionof FSH and LH during diet A suggests that greater ketosis increases renal gonadotropin clearance.