Low-carb diets for high insulin levels

May 28, 2007 08:54 GMT  ·  By

It seems that what you mustn't eat when you try to lose weight is linked to your insulin levels.

This is the conclusion of a research made on 73 obese young adults. "A major question in the field of obesity is, why can some people do well on conventional weight-loss diets, while others on the very same diets do very poorly?" said senior author Dr. David Ludwig, director of the Optimal Weight for Life clinic at Children's Hospital Boston. "The usual answer is motivation and compliance -- that people just don't stick to their diets. But our findings show that biology determines why some people do well on one weight-loss diet and not on another."

Low-glycemic-load diets decrease the rapidly-digested sugars that raise quickly the blood sugar and insulin levels (like white bread, refined breakfast cereals and concentrated sugars), replaced by sugars that are digested more slowly (like whole grains, fruits, vegetables, nuts and legumes).

A 2004 research made by the same team discovered that rats whose insulin levels were the highest 30 minutes after ingesting oral glucose (sugar) were those that gained the most weight. This fact made researchers suppose that people with high insulin levels could be similarly sensitive to the glycemic load, and could react quickly to a low-glycemic load diet.

The volunteers followed either a low-fat diet or a low-glycemic-load diet, and their insulin response was tested. The diets were not calorie restrictive; the volunteers just had to shift the food items.

Every six months, unannounced phone calls were made just to check their constancy to their diets. Protein and fiber intake, physical activity and satisfaction matched in the two groups.

In six months, those with the highest insulin secretion lost 2.2 lbs (1 kg)/month on the low-glycemic-load diet, while the subjects who were on the low fat diet just 0.9 lbs (350 g)/month. In 18 months, the overall weight loss was 12.8 lbs (5 kg) in the low-glycemic-load group, but just 2.6 lbs (1kg) in the low-fat group.

The low-glycemic-load diet also induced a much higher loss in body-fat percentage, and they did not put back weight between 6 to 18 months, when usually diet loss is regained.

Those with low insulin secretion did not display significantly higher weight loss and fat loss between the low-glycemic-load and low-fat diets. "These findings can allow clinicians to individualize the treatment of obesity by first giving patients an oral glucose tolerance test," said Ludwig.

"People who make a lot of insulin may do especially well on diets that reduce glycemic load. They tend to do very poorly on low-fat diets, which are generally high in carbohydrates and raise insulin levels even further, which in turn causes weight gain."