The Study
Effects of total energy withdrawal (fasting) on thelevels of growth hormone, thyrotropin, cortisol, adrenaline, noradrenaline, T4, T3, and rT3 in healthy males.
This study watched what happened to 12 guys' body chemicals when they didn't eat for 10 days. It saw some numbers go up and down, but it didn't compare them to people who ate normally. So we can't say fasting caused the changes — we just saw what happened in this small group.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
When healthy men didn't eat for 10 days, their bodies changed hormone levels to save energy.
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 521 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — these changes help the body slow down metabolism and protect vital organs during starvation.
- 2T3 dropped sharply, reverse T3 rose sharply, growth hormone spiked, cortisol and adrenaline went up slightly, T4 and TSH dropped a little, and all returned to normal after eating again.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Acta medica Scandinavica
Year
2009
Authors
Jan Palmblad, L. Levi, A. Burger, Arne Melander, U. Westgren, H. Schenck, G. Skude
Related Content
Claims (5)
When the body experiences low energy availability or extreme stress, it converts more thyroxine into reverse T3, which lowers the metabolic rate.
In healthy, normal-weight men, ten days of complete fasting leads to a small reduction in thyroid hormone levels and a minor decrease in the hormone that stimulates the thyroid, reflecting reduced activity in the hormonal system that regulates metabolism.
In healthy, normal-weight men, not eating for ten days causes growth hormone levels to rise sharply, then partially decrease before eating resumes, showing a timed hormonal pattern during extended fasting.
In healthy, normal-weight men, ten days of complete fasting leads to a small, steady rise in cortisol and increased adrenaline in nighttime urine, reflecting heightened activity in the body's stress-response systems.
In healthy, normal-weight men, ten days of complete fasting causes a significant drop in triiodothyronine (T3) and a rise in reverse T3, and these changes reverse quickly when eating resumes.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.