The NIH says the changes are necessary because of studies linking extra weight to health problems. The American Heart Association recently added obesity to its list of major risk factors for heart disease and heart attack, along with smoking, high blood pressure, high cholesterol and a sedentary lifestyle. Some health experts reject the new guidelines, claiming people who aren't fat are now considered overweight. For example, under the new definitions, many professional athletes would be considered too heavy. Critics also worry that these lower weights will persuade doctors to start prescribing diet drugs for people who don't need them.
Some diet drugs carry health risks, such as an increase in blood pressure.