Scientists who study obesity at the cellular level say genetics determines people’s natural weight range, right down to the type and amount of food they crave, how much they move and where they accumulate fat. Asking how someone got to be so fat is as meaningless as asking how he got to be so tall. “The severely obese have some underlying genetic or metabolic difference we’re not smart enough to identify yet,” says Dr. Rudolph Leibel of Columbia University Medical Center. “It’s the same way that a 7-foot-tall basketball player is genetically different from me, at 5-foot-8.”
Fat has been blamed for cardiac trouble, diabetes and some forms of cancer. But fat-acceptance activists argue that the epidemiological studies that link fatness to disease often fail to adjust for non-weight-related risk factors found more often in fat populations. Poverty, minority-group status, too much fast food, a sedentary lifestyle, lack of access to health insurance or to nonjudgmental medical care, the stress of self-loathing and being part of a stigmatized group — all are more common among fat people, and all are linked to poorer health outcomes at any weight. This makes it harder to say to what extent an association between obesity and disease is due to the fatness itself or to the risk factors that tend to go along with being fat.