It’s obvious that obese people more have fat than non-obese people, but it’s not as clear how it happens. Do obese individuals have more adipocytes (fat cells) than lean people, or do they have the same number of adipocytes, just larger ones? It turns out to be both. But the way that comes to pass is just being worked out by scientists. Engineering Professor Dr. Amit Gefen and his colleagues at Tel Aviv University recently demonstrated in a mouse cell line model that preadipocytes (precursors to fat cells) subjected to prolonged periods of “mechanical stretching loads” — the kind of weight we put on our body tissues when we sit or lie down — differentiate significantly faster, and retain significantly larger fat droplets, than those that are not. The research was published in the American Journal of Physiology — Cell Physiology .