The Claim
In rats subjected to 2 weeks of 50% caloric restriction followed by 1 week of isocaloric refeeding, skeletal muscle contraction and relaxation kinetics are significantly slowed, with time to half-relaxation increasing by 4.75 ms, and this persists during weight recovery, correlating with a 13.4% increase in slow-twitch muscle fibers and reduced local thyroid hormone activation, which contributes to suppressed thermogenesis and accelerated fat regain.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
Rats that underwent 2 weeks of severe calorie restriction followed by 1 week of normal eating showed slower muscle relaxation, a 4.75 millisecond increase in time to half-relaxation, a 13.4% increase in slow-twitch muscle fibers, and reduced thyroid hormone activity in muscle tissue, which was associated with lower energy expenditure and faster fat regain during recovery.
See the scientific wording
In rats subjected to 2 weeks of 50% caloric restriction followed by 1 week of isocaloric refeeding, skeletal muscle contraction and relaxation kinetics are significantly slowed, with time to half-relaxation increasing by 4.75 ms, and this persists during weight recovery, correlating with a 13.4% increase in slow-twitch muscle fibers and reduced local thyroid hormone activation, which may contribute to suppressed thermogenesis and accelerated fat regain.
When food intake drops sharply, muscle tissue reduces its ability to convert thyroid hormone into its active form, which switches muscle fibers from fast-burning to slow-burning types. Slow fibers contract and relax more slowly, using less energy and producing less heat. This energy-saving state continues even after eating returns to normal, causing the body to store more fat instead of burning it.
What the research says
1 studyWhen rats eat less for two weeks and then go back to normal eating, their leg muscles get slower at contracting and relaxing — and this doesn’t fix itself even after they regain weight. This slowdown is tied to a change in muscle type and less active thyroid hormone in the muscle, which makes the body burn less energy and store more fat.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.