Is your fight with obesity genetically programmed? Or are you predisposed to an aggressive cookie addiction? It’s easy to blame obesity on laziness or overeating, but is there really something more to it?
Genes, hormonal imbalances, and even viruses are now acknowledged to play a role in obesity. Eating less and working out more, in fact, don’t have nearly as much to do with weight loss as you might assume. Here is the latest (and often unexpected) thinking behind size and thighs, fatness and fitness.
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1. It Really Is Genetic
When scientists first discovered it in certain chubby mice, they called it simply the fatso gene. Years later, when they scoured the human genome for markers that increased vulnerability to type 2 diabetes, the fatso gene (now more politely called FTO) showed up there too. Turns out, people with two copies of the gene were 40 percent more likely to have diabetes and 60 percent more likely to be obese than those without it. Those with only one copy of the gene weighed more too.
Scientists now suspect that there are lots of fat genes. There could be as many as 100 of them, each adding a couple of pounds here and a pound or two there. That’s a noticeable difference when it comes to how much more fat we need to burn off.
2. Some People Just Have More Fat Cells
And the range is enormous, with some people having twice as many fat cells as others have. Even if you’ve lost a few pounds (or gained some), your fat-cell count remains, holding tight to the fat already inside and forever thirsting to be filled up with more. (To add insult to injury, the fat cells of overweight and obese people hold more fat too.)
New fat cells emerge during childhood but seem to stop by adolescence. Those of us destined to have a lot of these cells probably start producing them as young as age two. The cells’ rate of growth may be faster, too-even if kids cut way back on calories.
You may think this new discovery is depressing. But it isn’t all bleak. You’re better off with more fat cells than with fewer fat cells that become overstuffed and enlarged. (New research suggests that the overstuffed group are more vulnerable to obesity—related health complications.) So while you can’t reduce your total number of fat cells, there are things you can do to keep them small.
3. You Can Change Your Metabolism
Another Scandinavian team looked into what happens at the cellular level when you gain weight. Kirsi Pietiläinen, PhD, an assistant professor of nutrition at Helsinki University Central Hospital, studied sets of twins where one was fat and the other thin, and learned that fat cells in heavier twins underwent metabolic changes that make it more difficult to burn fat. Pietiläinen’s team suspects that gaining as little as 11 pounds can slow metabolism and send you spiraling into a vicious cycle: As you gain more fat, it becomes harder to lose it.
How to get back on track? The more I learn on the job, the more I’m convinced we need physical activity.
4. Stress Fattens You Up
The most direct route is the food-in-mouth syndrome: Stressful circumstances (your bank account, your boss) spark cravings for carbohydrate-rich snack foods, which in turn calm stress hormones. (When researchers in one study took away high-carb food from stressed mice, their stress hormones surged.)
Stress hormones also ramp up fat storage. For our prehistoric ancestors, stress meant drought or approaching tigers, and a rapid-storage process made sense; we needed the extra energy to survive food shortages or do battle. Today we take our stress sitting down—and the unused calories accumulate in our midsection.
To whittle yourself back down to size, in addition to your usual workout routine, make time for stress relief—whether it’s a yoga class or quality time with family.
5. Mom’s Pregnancy Sealed Your Fate
A mother’s cigarettes increase the risk of low birth weight, and alcohol can damage her baby’s brain. So why wouldn’t unhealthy foods wreak similar havoc? A growing body of science suggests that sugary and fatty foods, consumed even before you’re born, do exactly that. A Pennington study on rodents reports that overweight females have higher levels of glucose and free fatty acids floating around in the womb than normal-weight ones do. These molecules trigger the release of proteins that can upset the appetite-control and metabolic systems in the developing brain.
What’s true for mice is often true for humans too. Doctors from State University of New York Downstate Medical Center compared children born before their mothers had gastric bypass surgery with siblings born later. Women weighed less after the surgery, as expected, but their children were also half as likely to be obese. Because siblings have such similar genetic profiles, the researchers attributed the weight differences to changes in the womb environment. Moms-to-be, take note: You can give your kids a head start by eating well before they’re born.
6. Sleep More, Lose More
When patients see Louis Aronne, MD, they’re as likely to have their sleep assessed as their eating habits. If patients are getting less than seven to eight hours, Dr. Aronne may prescribe more shut-eye rather than the latest diet or drug. With more sleep, he says, “they have a greater sense of fullness, and they’ll spontaneously lose weight.”
Why? University of Chicago researchers reported that sleep deprivation upsets our hormone balance, triggering both a decrease in leptin (which helps you feel full) and an increase of ghrelin (which triggers hunger). As a result, we think we’re hungry even though we aren’t—and so we eat. Indeed, sleep may be the cheapest and easiest obesity treatment there is.
7. Achoo! A Virus Can Cause Obesity
Adenoviruses are responsible for a host of ills, from upper respiratory tract problems to gastrointestinal troubles. The link to fat was uncovered when researchers at the University of Wisconsin injected chickens with the viruses and found that certain strains fattened them up.
Stem cells, known for their chameleonlike abilities to transform, also turned into fat cells when infected with the viruses. “The virus seems to increase the number of fat cells in the body as well as the fat content of these cells,” says Nikhil Dhurandhar, PhD, now an associate professor of infections and obesity at Pennington.
Human studies, including comparisons of twins, suggest that obese people are indeed more likely to harbor antibodies for a particular virus, known as adenovirus-36.
We have flu shots; could an obesity vaccine be the next step? It may sound far-fetched, but “that’s what they said about cervical cancer too,” says Dhurandhar.
8. Cookies Really Are Addictive
While food is not addictive the way cocaine or alcohol is, scientists in recent years have found some uncanny similarities. When subjects at Monell Chemical Senses Center in Philadelphia were shown the names of foods they liked, the parts of the brain that got excited were the same parts activated in drug addicts. It may have to do with dopamine, the hormone linked to motivation and pleasure, say researchers at Brookhaven National Laboratory in Upton, New York. If obese people have fewer dopamine receptors, they may need more food to get that pleasurable reaction.
9. Ear Infections Can Taint Your Taste Buds
For years, the team at Linda Bartoshuk’s taste lab at the University of Florida wondered why people who tasted food less intensely than others seemed more likely to be fat. Researcher Derek Snyder had a theory: Could an ear infection, which can damage a taste nerve running through the middle ear, be the missing link? After tabulating 6,584 questionnaires, the team discovered that those over 35 who had suffered several ear infections had almost double the chance of being obese.
Responses to additional questions provided clues as to why. Former ear-infection patients were a little more likely to love sweets and fatty foods—perhaps because the damaged nerve causes them to have a higher threshold for sensing sweetness and fattiness. Even a small increase in calories from bad food choices adds up over time.
Childhood ear infections are as hard to avoid as the colds that tend to bring them on, but limiting passive smoke seems to drive down incidents of ear infection. If you’re an overweight adult who suffered a severe ear infection as a child, it may be worth paying attention to the taste and texture of your food. Simply finding healthier substitutes, such as fruit instead of candy, or olive oil instead of butter, may help drive you toward eating better and weighing less.