The Claim

Skeletal muscle upregulation of type 3 deiodinase (D3) during weight regain reduces local triiodothyronine (T3) availability, which decreases muscle metabolism, reduces ATP turnover, and increases contractile efficiency, resulting in preferential fat storage.

Source: Adaptive thermogenesis driving catch-up fat during weight regain: a role for skeletal muscle hypothyroidism and a risk for sarcopenic obesity

What the research says

Roughly balanced

Support and challenge are close. The picture may shift as more studies come in.

Supports
1score
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.

How it works
1 study reviewed
In plain English

During weight regain, increased activity of the type 3 deiodinase enzyme in skeletal muscle lowers local levels of the thyroid hormone T3, which slows muscle metabolism, reduces energy use, and enhances muscle efficiency, leading to greater fat accumulation.

See the scientific wording

Skeletal muscle upregulation of type 3 deiodinase (D3) during weight regain reduces local triiodothyronine (T3) availability, leading to slowed muscle metabolism, reduced ATP turnover, and increased contractile efficiency, which may contribute to preferential fat storage.

Why this might work

After weight loss, muscle tissue produces more of an enzyme that shuts down thyroid hormone locally. This slows down muscle metabolism, reduces how much energy the muscle burns, and makes the muscle more efficient at contracting. As a result, less glucose is used by muscle, so the body sends more glucose to fat tissue, where it is turned into fat. At the same time, muscle repair is blocked, so muscle mass does not recover, and fat keeps accumulating.

Verified mechanismbased on 1 study

What the research says

1 study

  1. Study: Adaptive thermogenesis driving catch-up fat during weight regain: a role for skeletal muscle hypothyroidism and a risk for sarcopenic obesity

    After losing weight, muscles make more of a special enzyme that turns off thyroid hormone locally, making the muscles work slower and burn less energy. This energy saving causes the body to store more fat instead of rebuilding muscle.

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

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