Fasting and Testosterone: What's the Effect?

Short answer: typical intermittent fasting (16:8 and similar) is generally testosterone-neutral. Severe caloric restriction or prolonged fasting can suppress testosterone, particularly in lean men. Effects on testosterone aren't a strong reason to fast or avoid fasting.

Short-term intermittent fasting

Time-restricted eating windows of 8–12 hours per day, common in popular intermittent fasting approaches, generally don't have significant effects on testosterone in healthy men over weeks to months of consistent practice. They may modestly improve testosterone in overweight men through weight loss — but the testosterone effect there is from the weight loss, not the fasting itself.

Severe or prolonged fasting

Significant caloric deficit over extended periods, very-low-calorie dieting, or multi-day fasts can suppress testosterone. The body responds to sustained energy deficit by reducing reproductive function. This is more pronounced in already-lean men.

Practical takeaway

• If intermittent fasting fits your lifestyle and helps with weight management or eating discipline, fine — it's unlikely to harm testosterone
• Don't fast severely if you're already lean and want to support testosterone
• Don't expect intermittent fasting alone to raise testosterone

When to see a doctor

For real testosterone concerns alongside dietary patterns, book a confidential consultation with a Singapore-licensed doctor on Noah.