Stringent dieting may cause girls to stop menstruating, and will prevent boys from developing muscles. If the diet doesn't provide enough calcium, phosphorous and vitamin D, bones may not lay down enough calcium to help reduce the risk of osteoporosis later in life. And inducing vomiting can lead to an eating disorder called bulimia, which can result in serious health problems. Rapid weight loss from very-low-calorie "starvation diets" can cause serious effects in teenagers, such …showed first 75 words of 384 total…

…showed last 75 words of 384 total…those foods. Inevitably, you'll break down and binge," says Jo Ann Hattner, a clinical dietician at Packards Children's Hospital in Palo Alto, California. Then you'll not only gain those pounds back, you'll likely add a couple more. Experts call this cycle of weight loss and weight gain "yo-yo" dieting, and believe that the repeated stress on your body of losing and gaining weight may be at least as bad for long-term health as being overweight.