Why whine about obesity? For one thing, lots of people don't like being fat, and at least 18 percent of American adults are obese, with another quarter being overweight. For another, it's downright unhealthy. A study published in the Journal of the American Medical Association last fall found that between 280,000 and 325,000 Americans die prematurely each year from obesity, defined as a a body mass index of at least 30.
That means obesity kills almost as many people as tobacco.
Obesity can kill by:
increasing the concentration of fatty acids in the blood; these chemicals are deposited as artery-clogging plaque, causing heart attacks
raising the odds of adult-onset (type II) diabetes, one of the most deadly diseases in America
causing some cases of breast cancer and other malignancies.
For another, obesity is increasing. Another JAMA study found that obesity had increased almost 50 percent just between 1991 and 1998, from 12 percent of the American population to 17.9 percent. The researchers commented that "A steady increase was observed in all states, in both sexes, across age groups, races, educational levels."
As we age, we bulge. It's not just true of Shizgal's couch-potato rats, but of many people as well. Monica Lewinsky's apparent success notwithstanding, most people don't do very well on diets.
One problem arises in the "starvation reflex," which was designed by evolution to get us through lean times. As your food intake falls, your body begins to use the remaining food more efficiently. That makes more sense when food is scarce than when it's abundant.
And while many people find losing weight relatively easy, keeping it off is another story. "The majority of adults can't [reduce] their adult weight more than 10 percent, even though you get a lot of testimonials on TV about weight loss," says George Blackburn, past president of the North American Association for the Study of Obesity. "It appears to take a lot of discipline and luck to do that."
Blackwell says body weight seems to be governed by a "settling point" that can ratchet steadly upward, but can only fall by 5 to 10 percent. Say you weigh 150 and want to shed a few pounds. According to Blackwell's notion of the settling point, you might lose up to 10 percent (15 pounds), taking you down to 135. But if you gain 10 percent, you'll soar to 165. Even with dieting and exercise, the best sustainable weight you can expect is back where you started -- not where you wanted to get.
Gaining weight, for adults, is like being stuck on the up escalator. "Nine times out of ten, your weight won't be more than 10 percent less than what it is now," says Blackburn, who's chief of the nutritional/metabolism laboratory at Beth Israel Deaconess Medical Center in Boston.
Honestly, when's dinner?
Thus, if you're overweight to start with, each gain makes it harder to reach a healthy weight. The reason? When you gain weight, you grow new fat cells that can start screaming "feed me" in unison.
When the fat cells shrink due to lack of food, they "shut down" and cease sending fullness messages via chemicals like leptin to the hypothalamus. Without that signal, "the brain is left naked to cope with McDonald's ads," Blackburn says. We can almost hear the starved hypothalamus signaling the brain, "Order me the double-bacon cheeseburger and a heap o' cheese fries, thank you so much."
Fortunately, the 5 to 10 percent figure is not reason for grieving, Blackburn says, since small decreases in weight can really help one steer clear of heart attacks, diabetes and early death.
Here's a painless weight-loss technique: chew gum!