Why muscle matters

Starving the body for weight loss leads to muscle loss and a slower metabolism

Here’s what can happen with crash dieting

It’s easy to think losing as much weight as possible in the least amount of time is the best way to reach your goals. But rapid weight loss can potentially slow your metabolism and cause you to lose too much muscle. Plus, because drastic weight loss tends to be unsustainable, you’re more likely to gain back the weight you lost and increase your body fat percentage, as illustrated below.

You lose 50 pounds, but 25 pounds comes from muscle, and only 25 pounds comes from fat. Your metabolism slows down, and when the weight returns, it is often regained mostly as fat instead of muscle.* The scale may end up back at the same number, but your body composition is very different, with less muscle, more body fat, and a slower metabolism.

Over time, this makes lasting weight loss harder. You may hit plateaus sooner, struggle to reach your goal weight, and regain weight more quickly once the restrictive dieting stops.

With each cycle of crash dieting and regain, the body often loses more muscle and stores more fat, which can further slow metabolism. Severe calorie restriction can also disrupt key hormones involved in hunger, energy balance, and weight regulation, while increasing the risk of serious health problems.

The impact on metabolic age and longevity

Higher muscle mass supports a stronger, more efficient metabolism, while increased body fat and muscle loss are linked to a higher metabolic age and increased health risks that impact mobility, energy, and longevity.