How much muscle mass do you lose when losing weight through dieting?
Dieting alone causes you to lose a meaningful amount of muscle mass alongside fat, but adding exercise and a little extra protein allows you to hold on to nearly half of that muscle loss on average.
When following a calorie-restricted diet without exercise, a substantial proportion of people also lose muscle mass. In 81% of the groups studied, among middle-aged and older adults with excess weight, at least 15% of weight lost came from lean mass, meaning muscles and related tissues. That is roughly one and a half kilograms of muscle mass for every ten kilograms lost, but it can be more.
How quickly you lose weight makes no demonstrable difference to how much muscle you lose. Losing weight fast does lead to a sharper drop in your metabolism, but muscle mass does not decline any more than with gradual weight loss, as long as the total amount of weight lost is the same.
Exercising alongside your diet makes a big difference. People who train retain, on average, nearly half of the muscle loss they would otherwise expect. In concrete numbers: combined training (strength and endurance together) saves an average of 1.2 kg of muscle mass compared with dieting alone, while strength training on its own saves nearly 0.8 kg. Endurance exercise alone has a smaller and less certain effect. Even during a very strict crash diet (fewer than 800 kcal per day), exercise proved effective: an average of about 0.8 kg more muscle mass was preserved, though this is based on only five small studies.
Eating more protein also helps, but the effect is more modest. A higher-protein diet preserves an average of 0.43 kg of additional muscle mass compared with a standard protein intake. For older people (aged 55 and above), a higher protein intake was linked to greater preservation of muscle mass in the arms and legs, but not to greater muscle strength or better day-to-day functioning. For those who train hard and want to build muscle at the same time: that is harder to achieve with a daily energy deficit of 500 kcal or more, even with intensive training. Muscle power does remain intact in that situation.
People who lose weight by combining exercise with adequate protein therefore retain considerably more muscle mass than those who focus on calories alone. Combined training paired with a higher-protein diet offers the best protection.
This answer draws on several combined summaries of multiple studies, giving it a reasonably solid foundation. The findings on exercise as a protective factor are the most consistent and well-supported. The effects of protein intake are somewhat less certain: the average benefit of 0.43 kg has been shown statistically but is small, and for older adults the finding comes from an analysis of only three studies with no effect on muscle strength or daily functioning. The effect of exercise during a crash diet comes from five small studies, which the researchers themselves flag as a limitation. For the comparison between fast and slow weight loss, the relationship has not been proven to be one of cause and effect.
Does cayenne pepper help with weight loss and fat burning?
Studies show that cayenne pepper produces a modest increase in fat burning and energy expenditure, and contributes to eating slightly less at a meal. As a supplement to a low-calorie diet, it has a biologically well-supported contribution.
Does 150 minutes of exercise per week help reduce liver fat?
Exercise clearly reduces liver fat, and you do not necessarily need to reach 150 minutes per week to benefit. Both aerobic training and strength training help; start with what is achievable and build from there.