Attention: a blueberry muffin is worse than a whole-wheat bagel! But is it really because of the difference in glycemic index—a measure of how much a carb raises your blood sugar? Swedish researchers are rethinking the concept—but other experts disagree with the notion entirely.

The glycemic index (GI) is a ranking of carbohydrates on a scale from 0 to 100 according to the extent to which they raise blood sugar levels after eating. Meaning, the lower the GI, the “better” the carb.


HIGHLIGHTS
Experts have developed a “gylcemic profile” that gives a better blood-sugar response picture than the glycemic index (GI)
The problem: It doesn’t tell you anything about how a meal impacts your blood sugar
Ignore both the GI and glycemic profile—they don’t tell you anything about a food’s health or nutrients

Now, researchers in Sweden are suggesting a new system: the glycemic profile. “The glycemic index only looks at blood sugar levels 2 hours after eating,” says Liza Rosen, Ph.D., and professor at Lund University in Sweden. “But the glycemic profile looks at the levels several times, until they return to that of fasting, which is usually 3 hours after eating.” The new method is better, they say, because it considers fluctuations of blood sugar over time—not just the level at one point.

The researchers are right to criticize the glycemic index. If you look at foods with high GIs, it’s glaringly obvious that it’s a horrible measure of good nutrition. “Ice cream and Snickers are technically low glycemic foods, since fat content usually lowers the GI,” says Alan Aragon, M.S., Men’s Health nutrition advisor.

On the other hand, a watermelon would have a high GI, but it’s low in calories and nutritious.

But Aragon says the glycemic profile isn’t much better. “Looking at the glycemic effect requires conditions that aren’t reflective of how people eat in the real world,” he says. “These studies look at the effects of carbohydrates in the absence of other foods after a fast.” This is a problem because fat lowers the blood sugar spike.

Trying to lose weight? Forget the glycemic index and the glycemic profile—they just don’t reflect real-life eating. “For it to matter at all, you’d need to eat a high carb, low-protein diet, actively avoid fiber, remain sedentary, and eat a lot more calories,” says Aragon.

If you’re still worried about your blood sugar, exercise! “Exercise uses the glucose stored in your muscles,” Aragon explained to us in Sweet Science. “And to replenish those stores after a workout, your body starts shuttling more of the glucose from your bloodstream to your muscles where it’s packed away for future use.” This helps reduce blood-glucose levels quickly, even after a high-sugar meal. Consider it another reason to lift weights: That extra muscle gives you a larger storage area for glucose, he says.