According to new research conducted by Johns Hopkins and published in the Journal of the American Medical Association, 56% of American adults ages 18 to 25 are overweight or obese. Using data from a nationally representative sample of 8,015 people in that age bracket, the researchers compared average weights over the past four decades. In that time, that population’s average body mass index, a measure of body fat based on a person’s height and weight, had increased by 4.6 points – from 23.1 (considered normal weight) to 27.7 (considered overweight). That shifted the number of overweight young adults from about 18% in the late 1970’s to nearly 24% by 2018.