Instapundit links to a Science Alert article about why we gain back weight lost on a diet. I will paraphrase one interesting finding.
We humans walk around in a body designed by evolution to survive in conditions of food scarcity. Our bodies are programmed to eat a lot when food is available because stored fat can help us survive the lean times, like winter and early spring before the new crops come in.
Modern agriculture and technology mean many of us no longer experience food scarcity, but rather its obverse, food abundance. Evolution - being a slow process - hasn’t caught up with our changed circumstances and isn’t likely to do so within the lifetime of anyone now alive.
In our modern lives food is almost always present, or nearby and available. Controlling our weight in the face of food abundance means fighting our instinctual programming to eat whenever food is available. The hopeful finding, while tentative, is this.
As you lose weight, your brain reduces your metabolic rate (the rate at which your body burns calories), making you subtly more efficient. The reality is, if there are two people of identical weight, one weight stable and the other having just lost weight, the latter will have to eat less food to remain the same weight.
It turns out that a hormone secreted from fat called leptin is largely responsible for this. One of leptin's key roles is to let the brain know how much fat you are carrying. The more fat you have, the more leptin is produced. So when you lose weight, your brain senses the corresponding drop in leptin.
What is exciting is that scientists have shown that if you administer just enough leptin to fool your brain into thinking you haven't lost any weight, then many of these weight-loss-related changes are mitigated. There is no treatment based on these findings yet – but watch this space.
Imagine if you could diet down to your preferred weight and then take a daily leptin pill to keep from gaining it all back. Now that would be something fine, sez I, who have been plump essentially forever.
