Studies that looked into the now banned drug, Fen-phen (D-fenfluramine)(1) indicate that the neurotransmitter serotonin plays a major role in weight loss. While the research is preliminary it appears that Fen-phen’s effects on neurons and melanocortin-4 receptors can be reproduced by serotonin. And according to Charles Raison, a psychiatrist with Emory University in Atlanta, drugs such as Prozac and Zoloft were believed to cause weight loss.

While the researchers are looking for a new drug to help with weight loss, we already know an effective and natural way to boost serotonin levels, exercise. Another natural therapy that appears to increase serotonin levels is bright light. As someone who sometimes struggles with seasonal affective disorder (SAD), I know that deliberate exposure to either daily sunlight or artificial light can make a huge difference in my winter mood. My own solution to the winter blues is a daily walk.

Not surprisingly, when I started to walk regularly, I also started to lose weight. Conventional wisdom tells us that the weight loss happens because we burn calories and increase metabolism. Since I was losing a bit over a pound a week. At two miles a day, I should have been burning off about 230 calories. (Here’s the calculator I use.) At five days a week, that’s 1150 calories a week, just less than a third of the 3500 calories that constitute a pound. Was the extra weight loss coming from an increased metabolism? Maybe. Or was the effect of the increased serotonin that the exercise and extra sunlight provided by my walk also helping to control my appetite?

(1)Science Daily synopsis of the studies:

National Institute of Health
University of Texas Southwestern Medical Center