One hundred years ago today Alfred Wegener presented his Continental Drift hypothesis to much derision and scepticism. Alfred Wegener first thought of this idea by noticing that the different large landmasses of the Earth almost fit together like a jigsaw.
BMI readings under 18.5 mean you are underweight, and could put on a few pounds. If you fall between 18.5 and 24.9, youâre considered normal, while a BMI of 30 or higher qualifies as overweight. But in recent years, more researchers argue that itâs not the most accurate way to measure body weight. For years, scientists have said that BMI canât distinguish between fat and muscle, which tends to be heavier and can tip more toned individuals into overweight status, even if their fat levels are low.
Muscle weighs more than fat, so a muscular person may appear to have a higher BMI, or a frail, inactive person may have more body fat than is healthy. For adults 20 years and older: 1  A BMI below 18.5 (shown in white) is considered underweight. 2  A BMI of 18.5 to 24.9 (green) is considered healthy. 3  A BMI of 25 to 29.9 (yellow) is considered overweight. 4  A BMI of 30 or higher (red) is considered obese.