More Advances in Understanding Weight Control
I have on many occasions discussed the problem of over-simplifying the mechanisms controlling our weight and appetite. They are complex and have multiple fail-safes and multiple levels of redundancy, which is why most weight loss programs only last for short periods of time. The body gets used to the diet, believes that it is starving, and immediately gets to work to conserve energy: our metabolism slows and our physical activity levels begin to fall.
We can tinker with leptin, cortisol or insulin to our hearts’ content, and each will probably help for a while. But if we ignore the body’s starvation-protection mechanisms, to say nothing of the psychological, social and subtle aspects of weight, our efforts will usually be fairly short-lived. Most of us now understand that food intake is only part of the equation; we also need to maximize our metabolic rate and increase our level of physical activity. One of the problems has been how to help someone exercise whose body wants to go into starvation mode.
Steve Bloom’s group at Imperial College and the Hammersmith Hospital in London has published another valuable report helping to elucidate some of the complex mechanisms involved in appetite, weight and metabolism. Steve has been working in this area since the early 1970s, and is one of the most highly cited scientists in the world. In a field that constantly sees new discoveries replacing the old, he is unusual in that that virtually all of his work has stood the test of time.
This report concerns the intestinal hormone oxyntomodulin, which has a dual action, increasing energy expenditure as well as reducing food intake. It appears that oxyntomodulin may let the brain know it has an adequate energy supply and that it can afford to do productive things rather than just concentrating on food seeking behaviors or energy conservation. The hormone signals the brain that it can increase exercise by letting it know that the energy is available to do so.
At the moment oxyntomodulin has to be given by injection, and, given the complexity of the weight maintenance systems it is unlikely to be the whole answer.
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