Kalorirestriktion ökar muskelförlust vid vila

[King Grub]

Ingen god idé att dra ned på energiintaget för mycket om man tvingas vila

Muscle inactivity and low energy intake commonly occur in persons with acute or chronic disease, in astronauts during space flight, and during aging.

We used a crossover design to investigate the effects of the interactions of inactivity and calorie restriction on whole-body composition and protein kinetic regulation in 9 healthy volunteers.

Lean body mass (LBM) was measured by using dual-energy X-ray absorptionmetry before and at the end of 14-d periods of bed rest (B) and controlled ambulation (A) in patients receiving eucaloric (E) or hypocaloric (H) ({approx}80% of total energy expenditure) diets. Whole-body leucine kinetics were determined at the end of the 4 study periods by using a standard stable-isotope technique in the postabsorptive state and during a 3-h infusion of a 0.13 g · kg LBM–1 · h–1 amino acid mixture.

In the postabsorptive state, we found a significant (P = 0.04) bed rest x hypocaloric diet interaction for the rate of leucine oxidation, an index of net protein catabolism (A+E: 0.23 ± 0.01; B+E: 25 ± 0.01; A+H: 0.23 ± 0.01; B+H: 0.28 ± 0.01 µmol · min–1 · kg LBM–1). Bed rest significantly (P < 0.01) decreased amino acid–mediated stimulation of nonoxidative leucine disappearance, an index of protein synthesis (A+E: 35 ± 2%; B+E: 30 ± 2%; A+H: 41 ± 3%; B+H: 32 ± 2%). B+H decreased LBM by 1.10 ± 0.1 kg, which is significantly (P < 0.01) greater than the decrease seen with A+E, A+H, or B+E.

Calorie restriction enhanced the catabolic response to inactivity by combining greater protein catabolism in the postabsorptive state with an impaired postprandial anabolic utilization of free amino acids.

Calorie restriction accelerates the catabolism of lean body mass during 2 wk of bed rest. American Journal of Clinical Nutrition, Vol. 86, No. 2, 366-372, August 2007.

[Slartibartfast]

Har väl alltid varit ganska självklart?

[King Grub]

Nä. Inte att utnyttjandet av aminosyror i proteinsyntesen nedregleras. Det är inte bara ökad katabolism som sker, utan både ökar katabolism och försämrad anabolism.

[paddanboy]

Med detta avses inte kalorirestriktion med träning, utan just vila med kalorirestriktion?

Inte så konstigt...