From semi-starvation to the stage: a case report on indicators of low energy availability in a drug-free bodybuilder during contest preparation and peak week.
Level 4 - case-series / case-control
Single-subject longitudinal case report
PubMed 39606576 · doi:10.3389/fnut.2024.1465001
What was done
An 18-week longitudinal case study evaluated a single drug-free male bodybuilder during contest preparation and a subsequent 2-day energy repletion period. Investigators measured endocrine markers (free triiodothyronine [T3] and total testosterone [TT]), resting energy expenditure (REE), respiratory exchange ratio (RER), body composition (body mass, 8 skinfolds), resting heart rate, oral temperature, mood, and one-repetition maximum (1RM) strength.
What was found
From baseline to week 18: - Free T3 fell to clinically low levels (2.7 pmol/L) and total testosterone dropped to sub-clinically low levels (9.1 nmol/L). - REE decreased by -519 kcal (REE ratio 0.78), and RER decreased from 0.95 to 0.85. - Body mass reduced by -5.1 kg, with a sum of eight skinfolds loss of -15.7 mm. - Decreases in body mass correlated with decreases in oral temperature (r = 0.674, p = 0.002) and resting heart rate (r = 0.560, p = 0.016). - Relative 1RM strength decreased in the squat (-5.4%), bench press (-2.6%), and deadlift (-3.6%), with mood remaining stable until the final 2 weeks. - Following 2 days of modest energy repletion, free T3 increased by 18.5% (reaching 3.2 pmol/L), whereas total testosterone decreased by -20.9% (falling to 7.2 nmol/L).
Why it matters
The study tracks the physiological adaptations to low energy availability during natural contest preparation. It shows that short-term energy repletion can quickly elevate thyroid hormone (T3) while suppression of testosterone persists.
Limits
Findings are derived from a single participant (n = 1) and cannot establish population-level norms or apply to female athletes. The energy repletion observation was limited to 2 days, and unmeasured factors such as daily non-exercise physical activity and hydration status may have confounded the physiological markers.
Cited by
- supports Severe caloric restriction and reaching single-digit body fat in natural bodybuilders causes extreme suppression of testosterone, resulting in female-equivalent hormone levels.