The Study
The Combination of a Diversified Intake of Carbohydrates and Fats and Supplementation of Vitamin D in a Diet Does Not Affect the Levels of Hormones (Testosterone, Estradiol, and Cortisol) in Men Practicing Strength Training for the Duration of 12 Weeks
This study gave two groups of guys different diets and checked their hormone levels before and after. It found that one diet made cortisol (a stress hormone) go down a tiny bit, but didn’t change testosterone or other hormones. It doesn’t prove that eating more carbs or fat causes big changes in hormones—it just shows what happened in this group.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
Scientists gave 55 guys who lift weights either lots of carbs or lots of fat for 12 weeks, plus vitamin D pills, and checked their hormone levels before and after.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 548 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1The cortisol drop from carbs is tiny and likely not meaningful for recovery or muscle growth.
- 2Vitamin D increased but didn’t boost testosterone, contrary to some claims.
- 3Carbs lowered morning cortisol by 3.5%.
- 4Fat made vitamin D levels rise more.
- 5Neither diet changed testosterone or estrogen.
- 6Vitamin D went up, but didn’t affect hormones.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
International Journal of Environmental Research and Public Health
Year
2020
Authors
M. Wrzosek, Jakub Woźniak, D. Włodarek
Related Content
Claims (5)
Eating protein and carbohydrates can lead to lower levels of the stress hormone cortisol by influencing the hypothalamic-pituitary-adrenal axis.
In men taking 2000 IU of vitamin D daily for 12 weeks, blood levels of vitamin D rise more when their diet is high in fat than when it is high in carbohydrates.
In young, healthy men who regularly lift weights, eating a diet high in carbohydrates or high in fat—while maintaining sufficient protein and calories—does not change the levels of testosterone or estradiol in the blood.
Among young, healthy men doing strength training for 12 weeks, eating a diet high in carbohydrates was linked to a small but statistically significant decrease in morning cortisol levels, while a high-fat diet showed a slightly larger but not statistically significant decrease. This suggests carbohydrate intake might have a modest effect on reducing cortisol after exercise.
Taking 2000 IU of vitamin D daily for 12 weeks raises vitamin D levels in the blood of young, healthy men who were initially deficient, but this change is not linked to changes in testosterone, estradiol, cortisol, or SHBG levels.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.