The formula for building or maintaining muscle mass is pretty simple. Physical activity combined with protein intake is equal to building muscle. Unfortunately, it's not that simple for obese individuals. While some obese individuals may even have more muscle mass than normal weight adults, this muscle is of poorer quality. Studies have shown a reduction in different muscle functions and an increase in fat content of muscles in obese individuals. Muscle of obese individuals appears to also be resistant to the normal process of protein synthesis. Several studies have shown that obese adults have less muscle protein synthesis after food intake. Others have shown that protein synthesis in obese individuals can be less responsive to resistance exercises. For example, one study monitored amino acid levels in the blood and muscles of both obese and normal-weight adults. Researchers had subjects perform certain resistance exercises with one leg and leave one leg inactive, consume about 36 grams of protein, and then collected muscle biopsies after the exercise. The expected surge of post-exercise protein synthesis was greater in the normal-weight adults as opposed to the obese ones. While the size of the study was small, it did show an impairment in post-workout muscle synthesis and muscle recovery with obesity.
What's at the Root of the Problem?
This is possibly due to increased resistance to insulin, the accumulation of fat, and increased exposure to inflammatory chemicals (due to both muscle inflammation or total body inflammation). What are the health implications of this effect? While more research is still needed, we do understand that the normal balance between protein synthesis and protein breakdown is essential for maintaining muscle mass and renewing the proteins found in muscle. When protein synthesis is impaired, it affects normal metabolism and may contribute to reduced insulin action in skeletal muscle. This has the potential of leading to type 2 diabetes. If one is attempting to lose weight, impaired muscle protein synthesis may make it difficult to spare muscle. Instead, lean muscle mass might decrease in addition to fat mass.
Spare Muscle While Losing Weight
An important strategy to spare as much muscle as possible when losing weight is to include resistance exercise with healthy dietary changes (including proper protein intake). Whey-protein supplements can be a convenient, science-backed way to include adequate protein in your muscle-sparing weight loss efforts. Interestingly, one study focused on how whey protein influenced obesity-related hormones in obese women with PCOS (Polycystic ovary syndrome). Immediately after whey protein isolate ingestion, there were lower insulin spikes (which means less fat depositing ocurring) lower cortisol levels (this helps preserve muscle), and an increase in the ghrelin hormone (which is involved in feelings of satiety or fullness after a meal). Therefore, the good news is that a well-structured, regular exercise program that includes resistance exercise and adequate protein intake can help with some of the negative effects of obesity on muscle.
References
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