Set Points and Weight Loss Surgery

One of the things I’ve been reading a lot about is set points. Basically, your body has a set weight that it likes and it’ll do everything it can to keep you there. You can lose about 10% – 15% of your excess weight, and if you work hard enough, your body will probably go along with that. Much more than that, and your body goes to war with your diet. Judy Forman, in a Boston Globe article, says this:

If you’re talking merely 10 to 20 pounds – and nobody knows the actual figure – you probably can diet and exercise your way to a svelter self and stay there, provided you stick with your weight control program rigorously. Forever.

Depressing, but you know it’s true. Dr. Lee Kaplan, in the same article continues:

Only about 1 to 2 percent of obese people can permanently lose weight through diet and exercise alone, said Dr. Lee Kaplan , director of the weight center at Massachusetts General Hospital.

And then he sets us all free:

“Dieting is like holding your breath,” he said. “You can do it, but not for long. Your body is stronger than your willpower.”

Uh huh. Now this is what all those “diet and exercise” types never tell you. Some of ‘em don’t know and some of ‘em can’t make money off you if they tell:

One famous study conducted at the University of Minnesota during World War II illustrates the ineffectiveness of severe dieting. The researchers put 36 physically and emotionally healthy young men of normal weight on a strict diet, allowing them only half the calories they were used to. The men lost weight, but became psychological wrecks, obsessing about food, bingeing, and, even after the diet was over, eating way too much, often 8,000 to 10,000 calories a day until they regained the weight, recounted New York Times science writer Gina Kolata in her recent book, “Re-thinking Thin.”

In another classic study in the 1950s, researchers at Rockefeller University in New York City recruited obese people who were so desperate to lose weight that they agreed to live in the hospital for eight months, including a four-month period in which they subsisted on only 600 calories a day of liquid formula. They lost weight, Kolata noted. But, to the dismay of subjects and researchers, they all quickly regained the weight.

Here’s what happens:

When a very fat person loses a lot of weight by diet and exercise, the brain goes into panic mode, reading a complex array of chemical signals as proof of impending starvation. Metabolism slows. The body hangs on to every calorie it can get. The chemical signals that trigger appetite soar, creating a drive to eat so powerful you can’t resist. From the standpoint of evolution, this makes sense: Our DNA was built when we were hunter-gatherers to protect us against starvation, not obesity.

So after you go on a diet, not only is your body slowing your metabolism, it’s also flooding you with hormones and chemicals that trigger hunger. So if you were happy with a Quarter Pounder and a small order of fries before your diet, after your diet, you’re gonna need to super-size everything to feel an equivalent level of satisfaction. That isn’t you being undisciplined. It’s you responding quite normally to your body.

They don’t why it happens yet, but here’s their best current guess:

Consider one of the best-studied weight control hormones, leptin, which is made in fat cells and is designed to tell the brain: “Stop eating. I’m full.”

“Obese people usually have high levels of leptin because they have so many fat cells making it,” said Dr. Eleftheria Maratos-Flier, an obesity researcher and associate professor of medicine at Beth Israel Deaconess Medical Center. “The heavier you are, the higher the circulating leptin.” In theory, being fat should mean that the brain would be flooded with “stop eating” signals.

But when people go on severe diets, “they lose more leptin than you would expect. So the brain thinks there is less fat than there ought to be,” which makes people eat more, she said.

And now we’re back to diet and exercise and why it doesn’t work:

Put differently, some researchers believe that one reason weight loss programs ultimately fail is that diet and exercise do not change the body’s “set point,” the thermostat-like mechanism in the hypothalamus and other parts of the brain that keep weight fairly constant.

And that brings us round to weight loss surgery. The article goes on to talk about gastric bypass, but there’s no evidence that all patients need to go that far. We know that patients who have had lap band surgeries lose as much weight as patients who have had gastric bypass, and they keep off as effectively as well. Though there are reasons for some to choose other types of weight loss surgery over lap bands, for most of us, the less invasive the surgery the better.

And here’s the conclusion about long term weight loss from the Medical Journal of Australia. LAGB being Gastric Banding:

All bariatric procedures have been able to achieve loss of more than 50% of excess weight.24,27-29 The ASERNIP-S systematic review showed greater weight loss after RYGB than LAGB during the first 2 years after the procedure, but the difference in weight loss was not significant at 3 and 4 years.24 In a recent review,23 we extended the data of the ASERNIP-S review by including all studies that included at least 50 patients, reported up to March 2004 (Box 5). This showed a substantial weight loss after both procedures, with an initial greater weight loss after RYGB but similar effectiveness for both procedures at 4, 5 and 6 years.

So, there ya’ have it – the big reason why diet and exercise do not work as we have been taught to believe they do.