The Claim

During 7 days of 240 kcal/day caloric restriction in obese adults, serum total T3, free T3, plasma pool, and production rate all decrease significantly, while metabolic clearance rate remains unchanged, and tissue uptake is reduced by approximately 50% despite only a 25% decline in free T3.

Source: Effects of caloric deprivation on thyroid hormone tissue uptake and generation of low-T3 syndrome.

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
25score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Quantitative
1 study reviewed
In plain English

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%.

See the scientific wording

During 7 days of 240 kcal/day caloric restriction in obese adults, serum total T3, free T3, plasma pool, and production rate all decrease significantly, while metabolic clearance rate remains unchanged, and tissue uptake is reduced by approximately 50% despite only a 25% decline in free T3.

Why this might work

When the body gets very little food, cells in tissues stop taking in thyroid hormone as efficiently, so even though there is still some hormone in the blood, the tissues get much less of it, which slows down metabolism.

Verified mechanismbased on 1 study

What the research says

1 study

  1. Study: Effects of caloric deprivation on thyroid hormone tissue uptake and generation of low-T3 syndrome.

    When obese people ate only 240 calories a day for a week, the active thyroid hormone in their blood dropped a little, but even less of it got into their body tissues — like a key that still exists but can’t turn the lock anymore. This suggests the problem isn’t just having less hormone, but cells can’t take it in properly.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

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