Want to Lose Weight? Eat Fiber.

A new study by UMass Medical School researchers found that the key to dieting may be more simple than we think. The study, published February 16 in the Annals of Internal Medicine, found that eating a least 30 grams of fiber per day contributed to weight loss and improved health.

Yunsheng Ma, MD, PhD, associate professor of medicine in the Division of Preventive and Behavioral Medicine and his UMass colleagues compared the weight loss and dietary quality of participants on the American Heart Association diet (AHA) to those on a simple high fiber diet. The main difference between the two—both recommend at least 30 grams of fiber per day—is that the AHA diet also adds in numerous instructions, such as limiting salt, cholesterol, fat, and alcohol.

Surprisingly, the researchers found that the AHA diet participants only had a minimally higher amount of weight loss. Both diets produced “clinically significant weight loss,” according to the study, and lowered blood pressure and improved insulin resistance—both keys to preventing diabetes and improving overall health.

“The more complex AHA diet resulted in slightly larger (but not statistically significant) weight loss, but a simplified approach emphasizing only increased fiber intake may be a reasonable alternative for individuals who find it difficult adhering to a more complicated diet,” Ma said.

The NIH funded study, titled “A Simple Dietary Message to Improve Dietary Quality for Metabolic Syndrome,” looked at 240 adult participants who were at risk for developing type 2 diabetes. According to the report:

Half were randomized to the high fiber diet and half assigned to the multicomponent AHA diet. The instructions for the high fiber diet called for simply increasing fiber intake to at least 30 grams per day. The AHA diet guidelines have 13 components, including limiting calories by eating more fruits, vegetables and whole grain foods; consuming at least 30 grams of fiber per day; choosing lean proteins; reducing sugar and salt consumption; drinking little or no alcohol; and balancing fat, carbohydrate, protein and cholesterol consumption to specific ratios.

Sherry Pagoto, PhD, associate professor of medicine at UMass, whose also writes a popular blog, called the FU Diet, and is famous for planking during presentations, was also co-investigator on the study. “We found that increasing dietary fiber was accompanied by a host of other healthy dietary changes, likely because high fiber foods displaced unhealthy foods in the diet,” she says. “Asking people to make one dietary change can have collateral effects on the rest of their diet. We hope to study this further.”

The study found:

The average weight loss after 12 months was 6 lbs. for the AHA followers and 4.6 lbs. for the high-fiber followers; all participants experienced lower blood pressure and showed improvement in insulin resistance and fasting insulin during the trial, which indicate this may be effective at warding off diabetes. These results suggest that focusing on a targeted fiber goal as a dietary intervention can be as clinically effective as the more intense AHA diet guidelines.

However, study participants did a lot more than just lose weight, they also “experienced improvements in metabolic syndrome, including lower blood pressure and decreased insulin resistance,” the study says.

“We were encouraged to see the decline of fasting insulin in the high fiber group at 12 months. Long-term improvements in insulin resistance have significant clinical implications for patients with metabolic syndrome,” Ma said.