Crazy for Carbs|
Scientists Debate Connection between Carbs and Obesity
ABC News December 6, 1999 20/20:
Americans now eat more carbohydrates than ever — 50 more pounds per person, per year, than a decade ago.
Carbohydrate-related diseases have also reached a peak. After decades of being warned away from fats, many people have turned to carbohydrates instead. At the same time, obesity levels in the country are greater than ever.
Is there a connection? Do carbohydrates lead people to become obese? Experts in the field have different opinions.The Zone
Biochemist Barry Sears, author of the best selling low-carbohydrate diet book The Zone, believes carbohydrates do cause people to gain weight. He has developed a controversial theory that suggests that people who eat a lot of carbohydrates get caught up in a cycle of overeating because carbohydrates can be addictive in a way other foods are not.
People who critique Sears’ theory have various problems with it, including some of his basic premises that carbohydrates lead to weight gain or that carbohydrates are more addictive than other foods.
However, many of Sears’ critics agree that a diet lower in carbohydrates is not harmful and can have positive results. And they agree with Sears that people with certain carbohydrate-related diseases, such as the little-known but dangerous Syndrome X, should absolutely maintain a low-carbohydrate diet.
Sears says the obesity crisis in America is a result of “carbohydrate hell.” He suggests that eating a lot of carbohydrates triggers a biological mechanism that lowers the blood sugar level and leads people to need a sugar boost and therefore to crave more carbohydrates. He says the cycle of eating and craving keeps them hooked on carbohydrates and causes overeating.
“You eat a big carbohydrates meal at 12. By 3 o’clock you’re hungry again. You eat more carbohydrates. By 7 you’re hungry again,” Sears says. His theory accepts some of the basic principles about how the body processes carbohydrates and takes them a step further. The basic principle is that carbohydrates turn into sugars that trigger the release of insulin. The insulin routes the sugars to our muscles for energy and stores the rest as fat.
Sears says eating a lot of carbohydrates triggers a flood of insulin. Because there is so much insulin, sugars are cleared from the blood so quickly that people feel hungry again after a very short period of time. So carbohydrates drive the sugar level up and then the insulin drives it down.A Critique of The Zone
Some scientists challenge Sears theory. Madelyn and John Fernstrom, who study the causes of overeating and run a weight management center at the University of Pittsburgh, say they believe the theory is too simplistic.
The Fernstroms say carbohydrates are not the only kind of food that people crave, nor is insulin the only cause of such a craving. They maintain people crave all different kinds of foods and for various reasons, such as hormones and brain chemicals.
Another critic is Dr. Gerald Reaven at Stanford University, who has conducted well-known research on the subject of insulin. Reaven feels that the information in The Zone misrepresented his research. He argues that his studies do not suggest that insulin or carbohydrates make people fat.Low-Fat Diet
Although these critics have problems with Sears theory, many do not see any harm in his low-carbohydrate diet, and they say its reasonably well-balanced. The diet recommends that people limit carbohydrate intake to 40 percent, mostly from fruits and veggies, and balance the rest of their diet with proteins and healthy fats.
And the critics agree that such a low-carb diet is recommended for people with certain diseases related to carbohydrates, such as Syndrome X.
Reaven explains that his latest insulin research does indicate that a high-carbohydrate diet can be dangerous for people who suffer from Syndrome X.Syndrome X
Americans need to know more about Syndrome X. It can be so lethal its putting 90 million, thats one in three people, at increased risk for a heart attack, Reaven says. The disease can double and even triple the risks of a heart attack.
People with Syndrome X have cells that are resistant to the effects of insulin. Their bodies have to compensate for the problem by producing abnormally large amounts of insulin. The more carbohydrates they eat, the more insulin is produced. The excess of insulin then triggers abnormalities in the blood that increase the risk of heart disease.
If someone has a family history of diabetes or heart disease, they are at increased risk for Syndrome X. Reaven recommends that such people check for the disease by testing their HDL cholesterol, triglycerides and blood pressure, all of which are warning signs.
As in Sears low-carbohydrate diet, Reaven recommends that people with Syndrome X cut down the carbohydrates in their diet to less than half. They also should increase healthy fats, the monounsaturated and polyunsaturated fats (in olive oil, avocados, almonds, fish), exercise and lose weight.
The guidelines of the American Heart Association, which recommend a diet of 55 percent
to 60 percent carbohydrates, are not designed for people with existing conditions such
as Syndrome X.