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A body mass index of 18.5 to 25 indicates you are at a healthy weight. A BMI of 25 to 30 shows a person is overweight, and a BMI of 30 or higher means a person is obese. These ranges are based on the effect body weight has on health and the probability of disease. According to the Center for Disease Control and Prevention (CDC), a high BMI is a strong predictor of disease in overweight or obese adults, including an elevated risk for cardiovascular disease, diabetes, cancer, high blood pressure and osteoarthritis.
Calculating BMI is quick and simple; however it does have limitations. One problem with using BMI as a measurement tool is that very muscular people may fall into the "overweight" category when they are actually healthy and fit. Another problem with using BMI is that people who have lost muscle mass, such as the elderly, may be in the "healthy weight" category–according to their BMI–when they actually may have reduced nutritional reserves. BMI, therefore, is useful as a general guideline to monitor trends in the population, but by itself is not diagnostic of an individual patient's health status. Further evaluation of a person should be performed by a health professional to determine his or her weight status and associated health risks.