Research indicates that frequent, rapid weight changes lead to a higher death rate and may increase the risk of coronary artery disease. Each time you lose weight and gain it back, your arteries become more clogged with cholesterol buildup, or plaque.
High cholesterol is one factor in atherosclerosis, high blood pressure, and heart attacks.
Yo-yo dieting also makes permanent weight loss more difficult. As you drop pounds, you lose both fat and muscle. Extreme calorie deprivation slows down the rate at which you burn calories. You end up heavier and unhealthier than ever. Staying fat isn't the answer either.