Cutting carbohydrates might also cut lifespan by up to four years, according to a new medical study.
The peer-reviewed research published in the medical journal The Lancet Public Health suggests low and high-carb diets could shorten life, and diets including some carbs could promote a healthy lifespan.
Scott Solomon, senior author on the study, called the research "the most comprehensive study of carbohydrate intake" ever.
The study analyzed self-reported data from more than 15,400 middle-aged Americans who participated in the Atherosclerosis Risk in Communities Study. The dietary patterns researchers found were compared against additional studies that included 432,000 people in more than 20 countries.
Self-reported data can be flawed, because it relies on the subject's memory. Another limitation of the study: Diets were measured only twice during the 25-year study period, at the start of the study and again six years later.
Researchers concluded that people who ate a moderate amount of carbohydrates lived four years longer than those with low-carbohydrate consumption and one year longer than those who ate a lot of carbohydrates. Low-carb diets were defined as less than 40 percent of calories from carbohydrates and high-carb diets were more than 70 percent of calories.
"Our data suggests that animal-based low carbohydrate diets, which are prevalent in North America and Europe, might be associated with shorter overall life span and should be discouraged," lead author Sara Seidelmann, fellow at Brigham and Women's Hospital in Boston, said in a statement.
Researchers observed that people who replaced carbohydrates with protein and fat from animals had a higher risk of early death compared to those who replaced carbohydrates with plant-based foods.
"These findings bring together several strands that have been controversial," co-author Walter Willett at Harvard T. H. Chan School of Public Health said in a statement. "Too much and too little carbohydrate can be harmful but what counts most is the type of fat, protein, and carbohydrate."