Evidence check: Fitness | LifestyleCheck in the context of Fruchtbarkeit

The evidence linking fitness and lifestyle to fertility is primarily human-observational and mechanistic. Numerous studies indicate that overweight (especially visceral obesity), physical inactivity, smoking, excessive alcohol intake, and poor diet can impair fertility in both women and men. In women, these factors disrupt hormonal balance (e.g., insulin resistance, LH/FSH ratio) and ovulation; in men, they reduce sperm quality. The effects are moderate but clinically meaningful. However, most data come from observational studies, so causality is not always clear. Genetic variants like FTO (rs9939609) have a small but measurable impact on body weight, which may indirectly affect fertility – but the direct effect on fertility is weak. MyBody-X tests provide indications, not diagnoses. A healthy lifestyle (balanced diet, moderate exercise, normal weight, no smoking) is the most important modifiable factor. The evidence strength is rated as 'human-moderate' because randomized controlled trials on fertility are challenging and ethically complex. In summary: lifestyle changes can improve fertility, but individual genetic and medical factors also play a role.