MANGAN: How aerobic exercise causes fat gain and muscle loss.

As humans get older, they lose muscle at a predictable rate if they don’t do anything about it. Between ages 50 and 70, most people will have lost 30% of their muscle mass, and then another 20% or so to age 80, a full half of all muscle being lost by that age. . . .

Two things can help prevent muscle loss with aging: a higher fraction of protein in the diet, and strength training. (High doses of testosterone, anabolic steroids, or growth hormone work too.)

Click the link to read more. There’s too much to excerpt here.

The important lesson here: if you want to lose fat and do so by dieting, resistance training (weightlifting, strength training) should always accompany your efforts, or you stand to lose muscle.

Aerobic exercise, especially when combined with dieting, can lead to muscle loss, resulting in lower metabolic rate and worse health, not to mention an increased risk of sarcopenia. Some studies have found that losing fat as measured by waist size results in lower mortality, but a decline in body mass index (BMI) raises mortality risk. (3) The explanation here is that losing fat is good, losing muscle is bad. Very bad.

Basically, the mainstream health and fitness establishment was wrong again, like they were with low-fat eating.