Caloric restriction induces energy-sparing alterations in skeletal muscle contraction, fiber composition & local thyroid hormone metabolism

[helvella]

I am struggling to come up with words to introduce this paper. Not because I can't think of anything so say, but because I am so sure that others will have lots to say!

Original Research ARTICLE

Front. Physiol., 16 September 2015 | dx.doi.org/10.3389/fphys.20...

Caloric restriction induces energy-sparing alterations in skeletal muscle contraction, fiber composition and local thyroid hormone metabolism that persist during catch-up fat upon refeeding

Paula B. M. De Andrade1†, Laurence A. Neff2, Miriam K. Strosova3, Denis Arsenijevic1, Ophélie Patthey-Vuadens2,3, Leonardo Scapozza2, Jean-Pierre Montani1, Urs T. Ruegg3, Abdul G. Dulloo1* and Olivier M. Dorchies2,3*

1Department of Medicine, Physiology, University of Fribourg, Fribourg, Switzerland

2Pharmaceutical Biochemistry, Geneva-Lausanne School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland

3Pharmacology, Geneva-Lausanne School of Pharmaceutical Sciences, University of Geneva, University of Lausanne, Geneva, Switzerland

Weight regain after caloric restriction results in accelerated fat storage in adipose tissue. This catch-up fat phenomenon is postulated to result partly from suppressed skeletal muscle thermogenesis, but the underlying mechanisms are elusive. We investigated whether the reduced rate of skeletal muscle contraction-relaxation cycle that occurs after caloric restriction persists during weight recovery and could contribute to catch-up fat. Using a rat model of semistarvation-refeeding, in which fat recovery is driven by suppressed thermogenesis, we show that contraction and relaxation of leg muscles are slower after both semistarvation and refeeding. These effects are associated with (i) higher expression of muscle deiodinase type 3 (DIO3), which inactivates tri-iodothyronine (T3), and lower expression of T3-activating enzyme, deiodinase type 2 (DIO2), (ii) slower net formation of T3 from its T4 precursor in muscles, and (iii) accumulation of slow fibers at the expense of fast fibers. These semistarvation-induced changes persisted during recovery and correlated with impaired expression of transcription factors involved in slow-twitch muscle development. We conclude that diminished muscle thermogenesis following caloric restriction results from reduced muscle T3 levels, alteration in muscle-specific transcription factors, and fast-to-slow fiber shift causing slower contractility. These energy-sparing effects persist during weight recovery and contribute to catch-up fat.

Full paper freely available here:

journal.frontiersin.org/art...

[Spareribs]

Hibernation again Rodders?

[gabkad in reply to Spareribs]

LOL!

[helvella Administrator in reply to Spareribs]

You fell asleep reading it, and will post a response in spring?

[gabkad]

So basically, bottom line: increase physical activity by a couple hundred calories per day, increase skeletal muscle mass to improve energy use, keep T3 going, and maybe decrease caloric intake by a couple hundred calories per day. That way a person would lose about 1 pound per week and do it safely.

Nothing new here except for the complicated verbiage.

However, nice to know that someone is vaiidating things by 'evidence based' blah blah.

No miracle weight loss and fitness formulae. Just gradual lifestyle changes that stick.

Will now crawl back under my rock with my inulin spiked vodka and soda.

[helvella Administrator in reply to gabkad]

It is the clarity of the statement in a formal paper that is good.

[Angel_of_the_North]

I think we've always known that, but not necessarily why. Dieting makes you fat, rebound weight gain etc.