BMI can give a false sense of good health. In medical terms, some people are classified as having metabolic obesity, normal weight (MONW) - or, more casually (and controversially), " skinny fat." Basically, this means that a person's BMI indicates a healthy weight, but their percentage of body fat is high - which is linked to all the same increases in health risks as obesity, per the Mayo Clinic.
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At home, though, many of us will round up our height while underreporting weight, according to an August 2013 review in Current Research in Nutrition and Food Science.
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If an older and younger person both have the same BMI, the older person (on average) will have more body fat, per the CDC. With age, a person's body composition shifts - to a higher weight with less muscle mass. BMI underestimates body fat for older adults. BMI is also known to be inaccurate for older adults, according to the NHLBI.Because muscle weighs more than fat, athletes or other muscular folks may fall into the overweight or obesity categories of the BMI chart, according to the American Council on Exercise (ACE). It may overestimate body fat for athletes or muscular people. "The problem with BMI is it doesn't really take into account body composition," Dr.