For decades, if not centuries, doctors have searched for the one diet that will help people maintain a healthy weight. But the latest thinking points to a different goal: finding not the best eating plan but the best eating plan for you. You’ve probably already noticed that when it comes to dieting, what works for your best friend—say, a low-carb plan—doesn’t necessarily work as well for you. But while that might have seemed like a purely personal preference, researchers now believe that it’s more a matter of biology.
Last year, for instance, Stanford University researchers gave genetic tests to 133 overweight and obese women who had already participated in a yearlong study in which they had been randomly assigned one of four popular low-carb or low-fat diets. The tests, which focused on three genes that affect how efficiently the body metabolizes fat and carbohydrates, determined which variations of those genes each woman possessed. The researchers then reanalyzed the original study data and found that women whose diets had matched up well with their low-fat or low-carb gene profiles lost 5.3 percent of their body weight, while those whose diets didn’t suit their biology dropped only 2.3 percent.
At Canyon Ranch, Mark Liponis, MD, the corporate medical director, has been conducting his own research on more than 6,000 patients for an upcoming book. We talked with Liponis, author of UltraLongevity, about how understanding your weight-loss genetics—?by looking at your body type—?can up your chances of dropping pounds.
Why would genetic differences play a role in our weight?
Humans have evolved in different environments around the globe, with different food supplies readily available. Maybe in one environment, people ate a lot of salmon and other fish and over time became more efficient at metabolizing protein, and maybe in another they ate a lot of corn and wheat and so got better at handling carbohydrates.
Would you recommend getting a genetic test to figure out which diet may work best for you?
No, not at this point. There are probably easier solutions than testing every person’s genes.
Such as what?
I think we are going to learn a lot more about how a person’s phenotype—her observable physical characteristics, which are influenced by her genetic structure—correlates with how she gains and loses weight. I think people are going to stratify into one of three groups based on how they look when they become heavier: those with big bellies, those with big butts and those who get big all over. And then we can design diets to fit each phenotype.
What have you learned from your work at Canyon Ranch?
If we put a person on a diet that matches her body type, she not only loses more weight but feels full most of the day and does not have trouble staying on that eating plan. We also see improvements in blood parameters, such as blood sugar levels and cholesterol measures.
So what type of diet seems to work best for specific body types?
Those with big bellies do well on a low-carbohydrate, low-glycemic diet. This kind of diet emphasizes meat and dairy products, which generally produce small fluctuations in blood glucose and insulin, as well as carbohydrates that contain a lot of fiber, such as bran cereals. On the other hand, people with big butts tend to do better with low-fat, high-carb diets—eating plans that often center on vegetables and grains while minimizing red meat. And those who are large all over seem to do well with a Mediterranean diet—one that is rich in fruits and vegetables, whole grains, nuts and seeds, legumes and healthy fats like olive oil.
As a woman reaches menopause, weight often shifts to her belly. Does that mean she falls into this so-called big-belly category?
Not necessarily. One of the best ways to determine if you are big bellied is to figure out your BBR, or butt-to-belly ratio. Here’s how: Measure your belly and buttocks at their widest points; for the butt, that’s the hips. Then divide your butt number by the size of your belly. So a woman with a 43-inch butt and a 36-inch belly would divide 43 by 36, yielding the number 1.19. A 1.1 or below is a big-belly type, who could do well on a low-carb diet. Someone who’s 1.1 to 1.25 would be fat all over and may do well with a Mediterranean approach. A ratio of 1.25 or over is a big-butt type, who may do best on a low-fat diet.
Wouldn’t it just be simpler to count calories and exercise more?
No. That equation—subtracting the number of calories burned from the calories taken in—is completely invalid. There’s a lot more going on in your body that affects your weight. For example, the microbes in your gut are critical; there are different types, and each type affects your appetite and metabolism differently, according to mouse studies done at Emory University. The composition of your specific microbe population can make it easier or harder for you to drop weight.
Do you believe that these findings can help control the current obesity epidemic?
Well, humans have been evolving for thousands of years. We used to have to hunt our food or go to a marketplace and trade for it. We have not had that long to adjust to the food supply we have now. It’s been only 80 or so years that we have had fast-food restaurants and grocery stores stocked with everything. Plus, we have genes for preserving calories, which protect us from famine. For the first time, we have to use what we know in order to choose what to eat rather than just eat what’s available. It’s going to be tricky. We’ll see how we do.
Originally published in the November 2010 issue of More.
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