The Science of Body Fat by Jerry Brainum 11/21

 

Recent surveys show that two-thirds of Americans are obese, meaning that they have too much body fat. Although there are movements related to body acceptance that try to convince people that they should accept their higher body fat levels, this is more of a dream than a reality. The truth is that being fat conjures images of gluttony and laziness. Most people view those who are obese are having no self-control over their food intake, coupled with a strong desire to avoid any physical activity. And in many cases that is true. The standard explanation for the cause of obesity is consuming more calories than you burn through physical activity. Despite this association with physical activity or exercise, many self-styled "experts" often suggest that exercise plays only a minor role in the fat reduction process. Some even claim that exercise works against fat loss by promoting an increased appetite. However, recent studies have discounted that notion. Exercise provides more of an anorexic effect if anything. But it remains true that most people become obese by simply eating too much food and not exercising enough. There are a few rare medical conditions that do predispose to obesity.

One example of this is a lack of leptin. Leptin is a protein produced in lipocytes or fat cells that among other functions signals the brain that fat cells are replete in stored fat. The leptin signal to the brain turns off the appetite and thus helps to prevent obesity. This effect of leptin was first observed in lab animals, such as mice. Mice deficient in leptin were enormously fat, but when they were injected with leptin, they lost all their excess body fat. This finding made headlines in 1994 when leptin was first discovered and led to the premature notion that leptin constituted the cure for obesity. The thought was that all obese people have to do was inject leptin and the fat would melt off them as it did in the lab rodents. It turned out, however, that this only worked if you were deficient in leptin. Further studies revealed that most obese people not only weren't deficient in leptin but produced greater amounts of it. The problem wasn't with leptin, but rather an inability of the brain to read the signal sent by leptin. In some cases, providing leptin injections (it had to be injected as a protein) did promote substantial fat loss in some obese people, likely by circumventing the lack of leptin signaling in the brain. But in the long run, leptin didn't turn out to be the magical cure for obesity as it was originally portrayed, except in cases of complete leptin deficiency.

While most modern societies take a dim view of those who are obese, this wasn't always the case.  If you view classic paintings, such as those by Reubens, you will note that the women shown in those paintings are invariably . . .