Some Low-Carb Diets Decrease Diabetes Risk, But Others May Raise It

When it comes to reduced-carb diets, it may be quality, not quantity, that matters most.

New research finds that animal-based, low-carbohydrate eating was associated with a higherType 2 diabetesrisk, whereas plant-based, low-carb eating was associated with a lowerdiabetesrisk. The research, recently presented in Chicago at the American心Association's Scientific Sessions conference, is considered preliminary until published in a peer-reviewed journal.

"To prevent the risk ofType 2 diabetesfor generally healthy people withoutprediabetesordiabetes, the quantity of carbs might not matter as much as the quality of the protein,fatsand carbs," said lead study author Yeli Wang, a research fellow in the department ofnutritionat the Harvard T.H. Chan School of Public Health in Boston. "The key is to pay attention to the quality of the food."

Low-carb diets are popular because research shows they can rapidly reduce weight within six to 12 months. However, it's unclear why they are so efficient at shedding pounds or how they affect long-term health. Diets that restrict carbs increase fat and protein, and one theory is that this leads to a feeling of fullness, which helps reduce hunger. Another theory is that restricting carbs increases the body's metabolism and helpsburncalories.

There are at least a dozen popular low-carb diets, including theketogenic diet– which severely restricts carbohydrates – and the Paleodiet, which emphasizes fruits, vegetables and lean meats and is modeled on foods that would have been available to humans during the Paleolithic Age. Some studies have suggested that very low-carb diets may improve blood glucose levels in people withprediabetesorType 2 diabetes. But the number of carbs consumed in these diets varies and the emphasis on eatingfatsraises concerns about how the diets may affectcholesterol levelsand heart health.

The new study shows some low-carb diets may be better than others, said Kristina Petersen, an assistant professor in the department ofnutritionat Texas Tech University in Lubbock.

"There's no standard definition for a low-carbdiet," said Petersen, who was not involved in the research. "At face value, they don't meet dietary recommendations very well. What this study shows is that perhaps they can, we just have to be mindful of what's in thatdiet."

In the study, researchers investigated the link between low-carb eating and the odds of developing Type 2diabetes, a major risk factor forheart diseaseandstroke. The analysis used dietary and medical data for 203,541 adults from three large national studies: the Nurses' Health Study, Nurses' Health Study II and the Health Professionals Follow-Up Study. The studies collectively covered a period from 1984 to 2017. Participants filled out questionnaires every four years about the foods they were eating and were followed for up to 30 years. None haddiabetesat the outset.

For the new study, whether a person'sdietwas considered low-carb was not defined by the exact quantity of carbohydrates they ate each day. Instead, researchers created a score based on the percentage of total energy each person got from their daily intake of proteins, fats and carbohydrates.

Using these scores, participants were divided into five equal groups. The lowest-carb group in the study got about 40% of daily energy from carbohydrates, Wang said. (By contrast, U.S. dietary guidelines recommend that carbohydrates account for 45%-65% of energy intake.)

评估质量的饮食,佛ods people ate were classified into 18 groups: whole grains, fruits, vegetables, nuts, legumes, vegetable oils, tea and coffee, fruit juices, refined grains, potatoes,sugar-sweetenedbeverages, sweets and desserts, animal fat, dairy, egg, fish or seafood, meat and miscellaneous animal-based foods.

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The preliminary data shows that people in the lowest-carb group who got more of their protein and fat from plant-based sources had a 6% lowerType 2 diabetesrisk – and if their eating further minimizedsugarand other refined carbohydrates, they had a 15% lower risk. By contrast, the lowest-carb group eating diets emphasizing animal protein and fat had a 35% higher risk ofType 2 diabetes– and a 39% higher risk if their diets also minimized whole grains.

Wang said oneweaknessof the study was that most of the people in it were white.

"We wonder whether our results could be generalized to other ethnic groups," she said. "We need to look at that, as well as people who consistently consumed very low-carb diets, such as theketo diet."

The American Heart Association recommends eating a diet that includes a wide variety of fruits and vegetables and healthy sources of protein, such as fish and seafood, legumes and nuts, low-fat or nonfat dairy and lean meats. It encourages choosing minimally processed foods over ultra-processed foods, and limitingsugar, salt andalcohol.

American Heart Association News covers heart and brain health. Not all views expressed in this story reflect the official position of the American Heart Association. Copyright is owned or held by the American Heart Association, Inc., and all rights are reserved. If you have questions or comments about this story, please email[email protected]

By Laura Williamson, American Heart Association News

By American Heart Association News

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