Exactly how high glycemic foods may impact health risk is still under investigation. But an animal study published by Ludwig in last week's issue of the British journal The Lancet provides some clues. In the study, one group of rats ate a starchy diet of high-glycemic foods while another received a starchy diet of low-glycemic food.
The study found that the rats eating high-glycemic food had 71 percent more body fat and 8 percent less lean body mass than those on the low-glycemic diet -- despite weighing the same.
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The animals that ate high glycemic food also had significantly higher blood glucose and insulin levels, three times the blood levels of trigylcerides and more cell abnormalities in the pancreas, the organ that produces insulin.
The findings suggest, Ludwig said, that "glycemic index is an independent factor that can have dramatic effects on the major chronic diseases plaguing developed nations -- obesity, diabetes and heart disease." Whilethese findings come from a study on rats, the evidence warrants further investigation in humans, Ludwig said.
Until scientists sort out all the glycemic index issues, here's what experts recommend:
No need to play the numbers. Sure, you can find plenty of glycemic index food lists to buy, read religiously -- and drive yourself crazy.
"I recommend against eating by the number for any diet," said Ludwig, who advises action that will sound very familiar to Lean Plate Club members: "All you need for most situations is to eat an abundant amount of fruit and vegetables and legumes [beans] and cut back on foods with refined starch and concentrated sugar," he said. "Fats can be eaten liberally as long as they are healthful fats. You need adequate amounts of protein, which could quite easily be from vegetarian sources" such as soy and other beans.
Eat little and often. Consume five to six small meals about two to three hours apart to keep blood sugar levels -- and insulin production -- steady. But the operative word here is small: about 200 to 300 calories per meal. If those little meals grow large, odds are you will, too.
Skip the whole-wheat pasta. Unless you really love it. White pasta is a dehydrated food that ranks low on the glycemic index, in fact "markedly lower than white bread," said Ludwig. Whole-wheat pasta simply has added wheat bran, which adds some fiber but "which does not lower the glycemic index at all," Ludwig notes. So have the regular pasta -- just be sure to limit portions to a cup of cooked pasta or less.
One more tip: Eat pasta al dente, cooked until firm but chewy. "It not only tastes better," Ludwig notes, "But it also has a lower GI index."
Add some healthy fat. Ludwig, Jenkins and Walter Willett of the Harvard School of Public Health are among the growing number of scientists who say that evidence suggests healthy fat -- olive, canola, safflower, sunflower and flaxseed oils, for example -- can help both with satiety and keeping blood sugar levels even.
Go ahead, snack. Just be smart about it. Choose popcorn instead of potato chips. Dip slices of red pepper, baby carrots and celery into bean dip, guacamole (a source of healthy fat) or salsa. Sip vegetable juice instead of fruit juice. Better yet, eat the fruit itself with a few nuts. And if you're tempted to have a sweet treat, make it a small one with a mix of sugar, healthy fat and protein, such as M&M's with peanuts.
Mix it up. That's an easy way to reduce the blood sugar effects of your favorite high-glycemic foods. So if you can't live without a sesame bagel, Rice Krispies and white rice, simply add foods that have a higher glycemic index to mute the rise in blood sugar. Eat those Krispies with skim milk, berries and a few nuts. Spread whipped regular cream cheese -- not nonfat, which is a high glycemic food -- on just half a bagel and add a slice of smoked salmon. Eat white rice with plenty of vegetables, a little lean meat, poultry, fish or beans.
Boost physical activity. In China, where white rice is a staple, rates of obesity and diabetes have been relatively low until recently. Not only is a more Western diet creeping into the country, but physical activity is declining. The glycemic index "probably doesn't matter at all, provided that you keep your body mass index under 23," Jenkins said. "If you stay skinny and physically active, you don't have to worry about all this nonsense."
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