A recent study, by Michael Rosenbaum and colleagues, at Columbia University Medical Center, New York, has provided new insight into the critical interaction between the hormone leptin and the brain’s response to weight loss. Although we have know for a few years that leptin plays a role in feelings of hunger. According to Byron and Mary Richards in their 2005 book, Mastering Leptin:

“Leptin is responsible for bizarre and erratic behaviour and cravings related to food, including the inability to attain and maintain a healthy body weight. Leptin is essential for survival; without it, the human race would have perished from starvation long ago. However, in the land of food on every corner, it is also the hormone that fuels addictive and compulsive behaviour. It is the reason why individuals will ‘start their diet tomorrow’.”

As we gain weight our bodies produce more leptin, which plays a key role in regulating appetite and metabolism. Leptin is actually produced by adipose tissue (fat). When we lose weight the amount of leptin also decreases with the fat that produces it. The problem with weight loss occurs because the lower levels of leptin trigger hunger signals in the brain. This is one of the main problems involved in maintaining lost weight.

There are other conditions that cause the body to produce less leptin. One such is lack of sleep. Another is sustained vigorous exercise. The first can be a major problem. I doubt that getting sustained vigorous exercise is a typical problem associated with weight gain. Although there is evidence that leptin given in combination with moderate aerobic exercise can cause weight loss, at least in rats.

While giving leptin shots to people who have lost weight can help them maintain their weight loss, overweight people don’t seem to respond well to leptin to help them lose the weight in the first place. The theory is that the extra fat causes leptin resistance. When leptin has been used in human clinical trials, the weight loss was unspectacular, and the hormone’s flurry of fame as a potential wonder drug petered out. Continued research has shown that leptin is an important hormone with a hand in many metabolic processes and undoubtedly has widespread effects that may influence diabetes as well as obesity Some research hints that it is possible to bypass that resistance by utilizing a downstream metabolite of leptin, 5-AMP-activated protein kinase (AMPK).

The good news is that by following some reasonable eating patterns and getting sufficient sleep, we can control our leptin levels and avoid cravings.

Although giving shots of leptin to people who have lost weight has proven to help prevent regain of weight, there are some problems with maintaining high leptin levels. It seems that high levels of leptin are also associated with raised blood pressure.

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