Open AccessTestosterone status following short‐term, severe energy deficit is associated with fat‐free mass loss in U.S. Marines
Author(s) -
Berryman Claire E.,
McClung Holly L.,
Sepowitz John J.,
GaffneyStomberg Erin,
Ferrando Arny A.,
McClung James P.,
Pasiakos Stefan M.
Publication year - 2022
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.15461
Subject(s) - medicine , endocrinology , testosterone (patch) , insulin resistance , trunk , zoology , chemistry , insulin , biology , ecology
Abstract 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 ( 15 N 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).