The Study
Effects of caloric deprivation on thyroid hormone tissue uptake and generation of low-T3 syndrome.
This study watched what happened to thyroid hormones in 10 people after they ate almost nothing for a week. It saw some changes, but it didn’t compare them to people who ate normally, so we can’t say the diet caused the changes — it just shows what happened in these 10 people.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
When people eat almost nothing for a week, their body stops letting thyroid hormones into tissues, even if those hormones are still in the blood.
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 525 / 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 — this means your metabolism slows down not just because hormone levels drop, but because your cells can't take in the hormones they need, even when they're present.
- 2Tissue uptake of T4 and T3 dropped by about 50%.
- 3Free T4 went up, but free T3 only dropped 25% — yet tissue uptake still halved.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The American journal of physiology
Year
1986
Authors
J. Van der Heyden, R. Docter, H. van Toor, J. Wilson, G. Hennemann, E. Krenning
Related Content
Claims (4)
In obese adults consuming 240 kcal per day for 7 days, total thyroid hormone levels in the blood stay the same, but the rate at which the hormone is made and cleared decreases, while the unbound form of the hormone increases even though less of it enters tissues.
During a 7-day very low-calorie diet in obese adults, the movement of thyroid hormones into body tissues decreases by about half, regardless of hormone levels in the blood.
In obese adults undergoing a 240 kcal/day calorie restriction for 7 days, levels of total T3, free T3, plasma thyroid hormone pool, and hormone production rate all decrease, metabolic clearance rate does not change, and tissue uptake of thyroid hormone drops by about 50% even though free T3 only falls by 25%.
Periodic increases in calorie intake raise leptin and thyroid hormone levels, which reduces the slowing of metabolism that occurs during long-term dieting.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.