Testosterone status following short‐term, severe energy deficit is associated with fat‐free mass loss in U.S. Marines

• Published in: Physiological reports Vol. 10; no. 18; pp. e15461 - n/a
• Main Authors: Berryman, Claire E., McClung, Holly L., Sepowitz, John J., Gaffney‐Stomberg, Erin, Ferrando, Arny A., McClung, James P., Pasiakos, Stefan M.
• Format: Journal Article
• Language: English
• Published: Oxford John Wiley & Sons, Inc 01-09-2022; Wiley-Blackwell; John Wiley and Sons Inc; Wiley
• Subjects: Alanine; Body composition; Body fat; Computed tomography; Dietary intake; Energy; eugonadal; Food; Health care; Hydration; hypogonadal; lean mass; Males; Metabolism; Military exercises; Original; Physical training; Protein biosynthesis; Protein turnover; Proteins; Questionnaires; Skills; Starvation; Testosterone; weight loss; United States > US
• ISSN: 2051-817X; 2051-817X
• DOI: 10.14814/phy2.15461

The objective of this study was to determine metabolic and physiological differences between males with low testosterone (LT) versus those with normal testosterone (NT) following a period of severe energy deficit. In this secondary analysis, 68 male US Marines (mean ± SD, 24.6 ± 2.4 y) were dichotomized by testosterone concentration (< or ≥ 10.5 nmol/L as determined from a single blood sample collected between 0600–0630 after an 8–10 h overnight fast by automated immunoassay) following 7 days of near complete starvation (~300 kcal consumed/d, ~85% energy deficit) during Survival, Evasion, Resistance, and Escape (SERE) training. Dietary intake was assessed before (PRE) SERE. Body composition (dual‐energy x‐ray absorptiometry and peripheral quantitative computed tomography) and whole‐body protein turnover (15N alanine) were assessed before (PRE) and after (POST) SERE. Mean testosterone concentrations decreased PRE (17.5 ± 4.7 nmol/L) to POST (9.8 ± 4.0 nmol/L, p < 0.0001). When volunteers were dichotomized by POST testosterone concentrations [NT (n = 24) 14.1 ± 3.4 vs. LT (n = 44): 7.5 ± 1.8 nmol/L, p < 0.0001], PRE BMI, total fat mass, trunk fat mass, and testosterone were greater and the diet quality score and total carbohydrate intake were lower in NT compared to LT (p ≤ 0.05). LT lost more fat‐free mass and less fat mass, particularly in the trunk region, compared to NT following SERE (p‐interaction≤0.044). Whole‐body protein synthesis, net balance, and flux decreased and whole‐body protein breakdown increased from PRE to POST in both groups (p‐time ≤0.025). Following short‐term, severe energy deficit, Marines who exhibited low testosterone had greater fat‐free mass loss than those who maintained normal testosterone concentrations. Altering body composition and dietary strategies prior to physical training that elicits severe energy deficit may provide an opportunity to attenuate post‐training decrements in testosterone and its associated effects (e.g., loss of lean mass, performance declines, fatigue).
Participants who maintained normal testosterone concentrations (≥ 10.5 nmol/L) following 7 d of severe energy deficit resulting from military training, compared to those who experienced low testosterone concentrations (< 10.5 nmol/L), had 1) greater BMI, total fat mass, trunk fat mass, and testosterone concentrations and a lower diet quality score and total carbohydrate intake at baseline, and 2) less fat‐free mass loss and more fat mass loss, particularly in the trunk region, in response to training.