Crash diets, which promise rapid weight loss, are unhealthy and unsustainable. While crash diets lead to initial weight loss, this is primarily due to loss of water weight and muscle mass, not fat.

"Weight loss" and "fat loss" are terms often used interchangeably, but it's useful to understand the difference. An expert explains how to target each.

Fat loss improves metabolism and heart health, reducing the risk of chronic conditions. Muscle tissue burns more calories than fat tissue, boosting metabolism even at rest. Lowering body fat, ...