It appears that with overweight follows a slight decrease in muscle protein synthesis. This would in practice imply that with an increase of body-fat follows a reduced impact of exercise on the body’s adaptability and response in compensation to stimulus and to rebuild muscle tissue. But it also implies the opposite, that a decrease of body fat allows for an increase in the bodily functions to improve in the adaptability of exercising.

Objective:

To investigate the sequential changes of protein synthesis in skeletal muscle during the establishment of obesity, considering muscle typology.

Experimental Design:

Adult Wistar rats were fed a standard diet during 16 weeks (C; n=14), or with a high-fat, high-sucrose diet during 16 (HF16; n=14) or 24 weeks (HF24; n=15). Body composition was measured using a dual-energy-x-ray absorptiometry scanner. The fractional synthesis rates (FSR) of muscle protein fractions were calculated in tibialis anterior (TA) and soleus muscles by incorporation of 1-13C-Valine in muscle protein. Muscle lipid and mitochondria contents were determined using histochemical analysis.

Results:

Obesity occurred in an initial phase, from 1 to 16 weeks, with an increase in weight (P

Conclusion:

Muscle mass, lipid infiltration and muscle protein synthesis were differently affected, depending on the stage of obesity development and muscle typology. Chronic lipid infiltration in glycolytic muscle is concomitant with a reduction of muscle protein synthesis, suggesting that muscle lipid infiltration in response to high-fat diet is deleterious for the incorporation of amino acid in skeletal muscle proteins.

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J Physiol. 2012 Jul 16. Time-course changes of muscle protein synthesis associated with obesity-induced lipotoxicity.
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