She and fellow researchers hypothesize that stress related to perceived racism causes elevated hormone levels in the central nervous system; an increase in cortisol secretion activates lipoprotein lipase, which increases fat retention..... is it not possible that it may be due to lack of exercise, poor eating habits and other lifestyle changes necessary to keep one within their ideal weight. Most Americans who are overweight could find any number of reasons to say they gained wieght without first recognizing the lifestyle they lead that may be the number one culprit.