Diet and Nutrition Claims

The key component of weight-loss plans like the Skinny Carbs Diet and the CarbLovers Diet is something called resistant starch (RS), so named because it resists being broken down and absorbed as it passes through the small intestine. RS is found in foods such as bananas (especially green ones), potatoes, bread, and pasta--things that get the ax from Atkins and other low-carb diets. Proponents of RS diets claim that such foods can help you shed pounds by burning fat and reducing hunger. While preliminary studies seem to provide a bit of support for the idea, I wouldn't go bananas over it.

How foods are processed and cooked affects how much RS they contain. High on the list are unprocessed whole grains, corn flakes, uncooked rolled oats, white beans, cold pasta, raw potatoes, and cooked potatoes that have been cooled. RS also comes in the form of specially formulated cornstarch that can be sprinkled into foods or used as a substitute for flour.

Lab studies have found that feeding rodents a high RS diet results in less body fat, perhaps by increasing levels of hormones that make the animals feel full and stop eating. Advocates of RS diets often point to that research along with a human study in which subjects were fed four meals with varying amounts of RS. The meal containing about 5 percent RS (as a fraction of total carbs) resulted in 23 percent more fat burning than the one with no RS. Sounds impressive until you know a few details: The study consisted of just 12 subjects, they ate just one of each meal, and testing lasted for just 24 hours.

In general, human studies--all of them small and short term--have yielded mixed results. Some show that RS increases feelings of fullness or results in lower food intake, but other research has found no such effects. There's little if any direct evidence that eating RS leads to weight loss, even in the short run.

If high RS diets do help you shed pounds, it may be because many RS foods are rich in fiber, which has been linked to lower body weight. In any event, you can't go wrong with oats, beans, brown rice, and other RS foods that are part of a healthful diet.

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