One of the studies I participated in was looking at receptor areas of my brain - and they found that I have scads of receptors in areas that respond to endorphins in a way that calms the body. My psychiatrist hypothesizes that my love of exercise is directly related to my receptors.
Exercise releases endorphins. While endorphins are often referred to the body's natural opiates, they aren't exactly like morphine or other drugs in the same class. So when I exercise, it is a treatment in a sense - boosting my endorphins makes my brain happier. Taking opiates on the other hand always makes me violently ill, depressed, and unable to move.
More recent research actually shows that you cannot really exercise enough to lose significant amounts of weight. Rather getting rid of high calorie drinks and foods will lead to significant weight loss. If you drink a can of Coke that is 140 calories. A woman of average weight would have to run about a mile to burn off the calories from that can of coke. Eat a Snickers bar and you have to run three miles. Beer - mile and a half. Burger King Whopper - you'd need to run 5-6 miles.
"Researchers from Loyola University Health System and other centers compared African American women in metropolitan Chicago with women in rural Nigeria. On average, the Chicago women weighed 184 pounds and the Nigerian women weighed 127 pounds."This is just a quote from an MSNBC article, but I've read a number of studies performed in the US looking at that type of data.
Many of the foods and drinks that aren't good for our weight, temporarily light up the nucleus accumbens -the pleasure center - so our body craves that food high. Sugar is a very potent stimulator. Not as much as crack cocaine, or methamphetamine (which is why those addicts get so thin because they replace their food high with a drug high.)
For years I struggled with eating disorders - both bulemia and anorexia - so I just keep wholesome foods aroung me. If I don't have goodies sitting in the house, I don't eat them nor will I go out to get them. While I've never been more than 20 pounds overweight, my depression gets steadily worse if I start gaining. Just eating healthy stuff and excercise for my endorphins keeps me more sane than any medications ever have.