I disagree strongly with the idea that losing muscle mass with age is inevitable or even that it is normal. It is super common but there are exceptions. We also think it is normal to have rising blood sugar as we age and we are told diabetes and many other chronic diseases are ever more likely and will progressively get worse as we age.
I believe those mistaken ideas are somewhat related. We are told a normal healthy fasting blood sugar is between 60 and 100 mg/dl. I disagree with that too. A fasting blood sugar of 100 may not cause the acute damages we see in diabetes but it is an indicator of some degree of insulin resistance. Insulin sensitivity plays a role in muscle uptake of amino acids and protein synthesis. Higher fasting blood sugar diminishes growth hormone and IGF1. I believe elevated blood sugar and triglycerides and elevated basal insulin contribute to accumulation of visceral and intramuscular fat. Adipose tissue fat cells only live on average for 10 years despite them being optimized for fat storage. Fat anywhere else is subject to more oxidative damage from increased metabolites. Muscle cells aren’t replaced, we are born with all of the muscle cells that we will ever have. When fat accumulates in muscle it slows the rate of turnover and gets increasingly rancid. The fat in addition to being an energy buffer has vital uses such as contributing to mitochondrial membranes and hormone signaling which can accelerate metabolic derangement when the fat is damaged.
Increasing protein in the diet helps overcome diminished muscle protein synthesis which I compare to injecting insulin is beneficial for type 2 diabetics. For a while. Increasing protein like increasing insulin masks the underlying issue of diminishing insulin sensitivity but if relied on heavily is likely to accelerate the underlying problems. For long term success keep an eye on things like insulin sensitivity and intramuscular fat.
I have SBMA a genetic muscle wasting disease that typically starts causing noticeable muscle loss in ones 20s at a pace matching that of people typically 40 to 50 years older. The disease is supposedly progressive and untreatable although it has been shown the rate of decline correlates strongly with a person’s HOMA-IR score - a measure of insulin resistance. I suffered a fast rate of deterioration when my blood sugar was pre-diabetic. Now with my blood sugar mostly in the 60-75 mg/dl range I can gain muscle again. I’m 3 months shy of 54. I’m hoping over the next 30 years I can regain much of what I lost over the previous 30.
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