"Leptin [computer-generated image of its structure by Vossman above] signals to the brain that the body has had enough to eat, or satiety," according to Wikipedia, which adds "A very small group of humans possess homozygous mutations for the leptin gene which lead to a constant desire for food, resulting in severe obesity." A new study suggests it isn't just the obese but all of us who are driven by the leptin imperative.
"They have essentially reinvented themselves, and they are worthy of the utmost admiration and respect," says Michael Rosenbaum — lead author of a brain-scan study by scientists at Columbia University Medical Center published in the July issue of Journal of Clinical Investigation — re folks like us who have "lost weight and kept it off." Melinda Beck of the WSJs Health Journal explains:
So, you ate less and exercised more and lost weight. But now the pounds are piling back on. You're hungrier than ever, and you can't seem to resist food. Once again, it's all your fault, right?
Wrong. Blame evolution, and the fact that for the vast majority of human history, famine was a bigger threat than flab. Even your seeming lack of will power is part of a complex biological system that drives humans who have lost weight to regain it …
"Loosely put, after you've lost weight, you have more of an emotional response to food and less ability to control that response," says Michael Rosenbaum …
The key driver of this system is leptin, a hormone secreted by fat cells. When humans (and rodents) lose 10% or more of their body weight, leptin falls rapidly and sets off a cascade of physiological changes that act to put weight back on. Skeletal muscles work more efficiently, thyroid and other hormones are reduced … all so the body burns 15% to 20% fewer calories, enough to put back 25 pounds or more a year.
"It's only been in recent decades that this mechanism is contributing more to obesity than survival," writes Beck, quoting Rudolph Leibel, a co-author of the Columbia study who helped discover leptin in the 1990s at Rockefeller University:
Now, anyone can summon an unlimited amount of food just with a cellphone.
"How do some people manage to overcome the leptin effect and keep weight off?" ponders Beck:
Generally by watching their food intake very carefully and continuing to increase their physical activity. "Anybody who has lost weight and kept it off will tell you that they have to keep battling," says Dr. Rosenbaum.
We don't know about increasing physical activity, as we've been walking about an hour a day through all the years of trim, tubby, trim, tubby, trim, tubby, obese and now normal BMI. But "mindful eating" is where it's at. As we wrote in the comments of Beck's "Putting an End to Mindless Munching" two months back:
It's mind over matter, and it worked for me.
Just under a year ago I jumped on the "mindful eating" bandwagon and started blogging about my experience in the The Cold Turkey Cookbook. It took about 5 or 6 months to lose 40 pounds, and I've never looked back.
The key is to treat yourself to a host of small portions of delicious and colorful, sweet and savory dishes, including fruits, veggies, a mini muffin and a small bit of meat or fish.
That and a little of the bubbly, as George Will asserts in "Survival of the Sudsiest":
The development of civilization depended on urbanization, which depended on beer. To understand why, consult Steven Johnson's marvelous 2006 book, "The Ghost Map: The Story of London's Most Terrifying Epidemic — and How It Changed Science, Cities, and the Modern World." It is a great scientific detective story about how a horrific cholera outbreak was traced to a particular neighborhood pump for drinking water. And Johnson begins a mind-opening excursion into a related topic this way:
"The search for unpolluted drinking water is as old as civilization itself. As soon as there were mass human settlements, waterborne diseases like dysentery became a crucial population bottleneck. For much of human history, the solution to this chronic public-health issue was not purifying the water supply. The solution was to drink alcohol.
"Often the most pure fluid available was alcohol — in beer and, later, wine — which has antibacterial properties. Sure, alcohol has its hazards, but as Johnson breezily observes, "Dying of cirrhosis of the liver in your forties was better than dying of dysentery in your twenties." Besides, alcohol, although it is a poison, and an addictive one, became, especially in beer, a driver of a species-strengthening selection process.
We'll drink to that.