Overview
The body interprets severe caloric restriction as famine — a life-threatening situation incompatible with reproduction. GnRH pulsatility reduces, LH and FSH fall, and testosterone production drops accordingly. This evolved protective mechanism becomes pathological in the context of intentional restriction. Very lean men in competition cut, bodybuilders, or those with disordered eating frequently exhibit secondary hypogonadism with full reproductive consequences.
How It Affects Fertility
- Reduced GnRH pulsatility from energy deficit signalling
- Falling LH, FSH, and testosterone in sequence
- Elevated cortisol (stress response to perceived famine)
- Elevated SHBG on very low calorie diets
Symptoms to Watch For
- Loss of libido and sexual function
- Fatigue and brain fog
- Loss of morning erections
- Mood disturbance and depression
What You Can Do
- 1 Avoid periods of severe caloric restriction before or during attempts to conceive
- 2 Prioritise protein adequacy — at least 1.6g/kg bodyweight during any dietary restriction
- 3 If in a cutting phase, time it well away from planned conception periods
- 4 Never eliminate dietary fat — it is the direct substrate for testosterone production
This content is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before making health decisions.