Full Article by Prevention (text format)
Potatoes get a bad rap as little more than a waist-thickening waste of calories. But amazing new research puts spuds squarely at the center of the latest weight loss buzz, along with other unfairly maligned carbs such as corn and rice. The reason: All these foods contain resistant starch, a unique kind of fiber you'll be hearing a lot more about. In fact, experts agree that it's one of the most exciting nutrition breakthroughs they've seen in years. "Resistant starch has the potential to become the next hot nutrition trend," says Leslie Bonci, RD, author of the American Dietetic Association's Guide to Better Digestion. Indeed, more than 160 studies have examined this little known nutrient's remarkable health and weight loss benefits.
Resistant Starch: The New Power Nutrient
Although this may be the first you've heard of resistant starch, it's likely been a part of your diet most of your life. Resistant starch is a type of dietary fiber naturally found in many carbohydrate-rich foods such as potatoes, grains, and beans, particularly when these foods are cooled. It gets its name because it "resists" digestion in the body, and though this is true of many types of fiber, what makes resistant starch so special is the powerful impact it has on weight loss and overall health. As a dieter's tool it can't be beat: Not only does it increase your body's ability to burn fat, but it also fills you up and reduces overall hunger. Its health benefits are truly impressive as well. Studies show it improves blood sugar control, boosts immunity, and may even reduce your cancer risk.
Resistant starch is bulky, so it takes up space in your digestive system. And because you can't digest or absorb it, the starch never enters your bloodstream. That means it bypasses the fate of most carbohydrates, which get socked away as body fat when you eat more than you can burn. Here are two more key ways resistant starch can help you drop unwanted pounds:
It ups your calorie burn. Unlike some types of fiber, resistant starch gets fermented when it reaches the large intestine. This process creates beneficial fatty acids, including one called butyrate, which may block the body's ability to burn carbohydrates. "This can prevent the liver from using carbs as fuel and, instead, stored body fat and recently consumed fat are burned," explains Janine Higgins, PhD, nutrition research director for the University of Colorado's Adult and Pediatric General Clinical Research Center. In your body, carbohydrates are the preferred source of fuel, like gasoline that powers your car's engine. Butyrate essentially prevents some of the gas from getting into the tank, and your cells turn to fat as an alternative. One study found that replacing just 5.4% of total carbohydrate intake with resistant starch created a 20 to 30% increase in fat burning after a meal.
It shuts down hunger hormones. Animal studies have found that resistant starch prompts the body to pump out more satiety-inducing hormones. A meal with resistant starch triggers a hormonal response to shut off hunger, so you eat less. Research shows that you don't reap this benefit from other sources of fiber.
Fighting Disease, One Potato at a Time
The research on resistant starch doesn't stop at weight loss. This powerful nutrient is also earning accolades as a major disease fighter from standard bearers such as the World Health Organization. Here's why scientists around the globe are so excited about its health benefits:
It can prevent cancer. Research shows that the butyrate created by resistant starch may protect the lining of the colon, making it less vulnerable to the DNA damage that triggers diseases, such as colon cancer. It can also create a pH drop inside the colon, which boosts the absorption of calcium and blocks the absorption of cancer-causing substances.
It may fight diabetes and heart disease.
Like other fibers, resistant starch helps control blood sugar levels. "Because it skips routine digestion, we see lower blood sugar and insulin levels following a resistant starch–rich meal," says Christine Gerbstadt, MD, RD, CDE, spokesperson for the American Dietetic Association. Blood sugar control translates into more energy and sustained energy. It also means long-term heart protection, because chronic high levels of blood sugar and insulin cause delicate arteries to become clogged and harden.
It boosts your immune system. "When you have low levels of good-for-you bacteria in your digestive system, it's very difficult to fight off disease," says Joanne Slavin, PhD, RD, a nutrition professor at the University of Minnesota. Resistant starch may boost the growth of probiotics, the same kind of healthy bacteria found in yogurt that keep bad bacteria in check.
How to Eat Enough
Right now, there is no specific target for resistant starch intake. But preliminary data shows that the average American woman consumes about 4 g of resistant starch each day. Experts such as Gerbstadt believe the research is strong enough to advocate doubling that.
Adding just 1/2 to 1 cup of cooled resistant starch–rich food per day can do the trick. See "6 Best Fat-Burning Foods" below for ideas, and follow this advice to maximize your intake.
Keep it cool. In cooked starchy foods, resistant starch is created during cooling. Cooking triggers starch to absorb water and swell, and as it slowly cools, portions of the starch become crystallized into the form that resists digestion. Cooling either at room temperature or in the refrigerator will raise resistant starch levels. Just don't reheat. That breaks up the crystals, causing resistant starch levels to plummet.
Look for fortified foods. A growing number of commercial foods have been bolstered with Hi-maize, the brand name of a resistant starch powder made from corn. You can use it in baking (and lower calories) by replacing up to one-quarter of traditional flour in any recipe without affecting taste or texture (King Arthur Hi-maize Natural Fiber, $5.95 per 12-ounce bag; kingarthurflour.com). Or, look for packaged products that include Hi-maize, as another easy way to boost your intake.