Eating High-Glycemic Carbs Doesn't Necessarily Cause Weight Gain, According to New Study

While not all carbs are created equal, consumers have been cautioned (especially if they are trying to lose weight or adjust their eating habits) to stay away from eating "fast carbs" and to prioritize adding "slow carbs" to their diet. When we say "fast" and "slow", we are talking about how quickly the carbs are absorbed in our bodies (for more on that, check out this explainer on complex carbs). However, a recent study determined very small quantitative differences between high-glycemic (fast carb) and low-glycemic (slow carb) foods.

Related: Is There Such a Thing as Good Carbs and Bad Carbs?

The study, released in the journal Advances in Nutrition, concluded that eating high-glycemic index (high GI) foods is no more likely to lead to weight gain than eating low-glycemic index (low GI) foods, and no less likely to cause diet-induced weight loss.

The research, which received financial support from Grain Foods Foundation, aimed to test the hypothesis that consuming high-glycemic foods causes fat storage and impacts body weight and that eating low-glycemic foods results in opposite effects. The glycemic index measures how fast a particular food raises blood sugar levels and assigns a value to each food based on the rate at which the food increases glucose levels.

Scientists analyzed data from 43 cohort studies from 34 publications (totaling almost 2 million adults) comparing low-GI and high-GI diets for weight loss. The study found that "GI, as a measure of carbohydrate quality, appears to be relatively unimportant as a determinant of BMI or diet-induced weight loss."

"This study is the first to definitively demonstrate that fast carbs do not make you fat," says study co-author Glenn Gaesser, Ph.D., a professor of exercise science in the College of Health Solutions at Arizona State University. "Contrary to popular belief, those who consume a diet of high-GI foods are no more likely to be obese or gain weight than those who consume a diet of low-GI foods. Furthermore, they are no less likely to lose weight."

So, what kind of carbs should you eat? "The key takeaway is that carbohydrates, regardless of type, can be part of a healthy diet and have a place on a healthy plate," says study co-author Julie Miller Jones, Ph.D. Instead of focusing on high- or low-glycemic foods, researchers advise focusing on the variety of carbs consumed as part of a balanced diet. (FYI, eating these six carbs can help you lose weight.)

Related: 25+ Weight-Loss Recipes Packed with Good-for-You Carbs

Jones says, "Over the past few decades, we've seen the blanket vilification of carbs, processed foods and foods made with refined grains. Science has shown that these foods in the right balance can be part of a dietary pattern that can promote a healthy weight and reduce disease risk. The truth is that eating a wide variety of carbohydrates, from fast-carb white bread to slow-carb bran flakes, and pairing them with smart choices from all the food groups can provide the nutritional benefits that healthy carbs, especially whole- and enriched-grain staple foods can offer."