Even to conscientious eaters, a slice of chocolate cake can be irresistible. What’s baffling is why we sometimes give in to temptation despite our better judgment.
Researchers at the Montreal Neurological Institute and Hospital (MNIH) have found a possible explanation: The second we see delicious-looking food, a hormone in our gut called ghrelin starts sending powerful signals to the brain telling us to eat that cake now.
This finding is one of many in an exploding field of research aimed at uncovering the causes of excess weight. “We’re closer to recognizing just how complicated obesity is,” explains Arya Sharma, MD, professor of medicine at the University of Alberta. The good news, he adds, is that the sooner we unearth what causes us to gain weight and hold on to it, the sooner we can find a cure for obesity, or simply a solution to dropping those extra 10 pounds.
For now, weight-loss treatments, typically calorie reduction and exercise, must be maintained for life—but here’s how to harness some surprising new discoveries.
1. Rethink what’s delicious
Using magnetic resonance imaging (MRI), the MNIH researchers studying the gut hormone ghrelin found that it increases the neural response—and, therefore, appetite in regions of the brain responsible for coding the incentive values of food. “In other words, when we see food we like, we are exceedingly compelled to eat it,” says Alain Dagher, a neurologist at MNIH. “Unfortunately, our brains are likely wired to value high-calorie foods, which is important if food is scarce or difficult to obtain,” he explains.
One way to counter this is to increase the appeal of low-calorie foods by thinking about them more positively.
2. Get your thyroid checked—again
Small dips in thyroid function are associated with weight gain, according to a study in the March 2008 Archives of Internal Medicine. When this gland in the neck does not secrete enough hormones, it can result in lower metabolic rates (symptoms include fatigue and weight gain).
However, Caroline Fox, MD, an endocrinologist at the National Heart, Lung, and Blood Institute, says her research group was surprised to discover that women whose serum thyrotropin (TSH) levels were relatively high, but still within the normal range used by doctors to diagnose thyroid conditions, gained up to four pounds over three and a half years compared to women whose TSH did not increase.
“If a patient feels she has gained excess weight or has trouble losing weight despite adherence to a healthy lifestyle, she should talk to her physician,” says Fox, who adds that this research is too preliminary to consider tinkering with the current range for medical diagnosis.
3. Avoid bisphenol A and other household chemicals
Research shows that exposure to endocrine-disrupting chemicals (EDCs) at an early stage in life can increase the risk of certain cancers; bisphenol A (BPA) may be one of these chemicals. Now a team at Tufts University has discovered yet another reason to avoid prenatal or perinatal exposure to BPA: It may cause weight gain later in life.
Retha Newbold of the National Institute of Environmental Health Sciences says the findings in animals may also be true for humans. “When a fetus or baby is exposed to endocrine-disrupting chemicals, the body’s set point [the balance between energy in, as calories, and energy burned] is irreversibly altered,” she explains.
Of course, EDC exposure is not the only risk factor for obesity—diet and exercise are major players—nor does exposure early in life guarantee weight troubles later. “But it does help explain why some people have more difficulty losing weight and keeping it off than others,” Newbold adds. For now, she recommends avoiding EDCs where possible, including phthalates (found in some cosmetics and cleaning products) and BPA. That means opting for fresh foods over canned (many of which have a lining that contains BPA), avoiding polycarbonate water bottles and not heating foods in plastic containers.
4. Don’t worry about an ample bottom; belly fat is the real problem
According to research published in the journal Cell Metabolism, subcutaneous fat, which is found around the hips and bottom, may actually provide some protection against type 2 diabetes. “Subcutaneous fat appears to make a substance that is secreted into the blood and improves insulin sensitivity and metabolism,” says C. Ronald Kahn, MD, a researcher from the Joslin Diabetes Center in Boston.
When it comes to belly fat, University of Western Ontario professor Kaiping Yang reported a startling discovery. The kind of fat cells found in the abdomen produce a hormone—neuropeptide Y—that acts as an appetite stimulant. (Appetite was formerly thought to originate only in the brain.) Worse, the hormone stimulates further fat cell production. This research, published in The FASEB Journal, suggests that women who tend to carry weight around their middle may find it harder to lose overall body fat.
And it’s tough to spot-reduce belly fat with exercise, say certified fitness consultant Scott Tousignant. The best approach to slim down all over is combined aerobic and resistance exercise. “When resistance exercises are done properly, they should elevate your heart rate,” he says.
Web exclusive November/ December 2008 Best Health magazine