02.16.2015
Action Points
- Note that, in this randomized trial, a high-fiber diet had a similar (modest) effect on weight loss as the traditional American Heart Association recommended diet.
- Be aware that, even in the high-fiber arm, daily fiber intake was significantly less than what is recommended for healthy adults.
A high-fiber diet pitted against the traditional American Heart Association (AHA) diet in obese patients led to similar amounts of weight loss after 1 year, reported researchers.
But the weight loss in both groups did not meet the study’s primary endpoint, which was a loss of 7% of baseline body weight, acknowledged authors Yunsheng Ma, MD, PhD, and colleagues at the University of Massachusetts, in the Annals of Internal Medicine.
A high-fiber diet pitted against the traditional American Heart Association (AHA) diet in obese patients led to similar amounts of weight loss after 1 year, reported researchers.
But the weight loss in both groups did not meet the study’s primary endpoint, which was a loss of 7% of baseline body weight, acknowledged authors Yunsheng Ma, MD, PhD, and colleagues at the University of Massachusetts, in the Annals of Internal Medicine.
“The weight loss is modest, 5 to 6 pounds [in each group],” Ma told MedPage Today in an email.
The 1-year randomized, controlled trial looked at 240 adults ages 21 to 70 years with metabolic syndrome and body masses indices of 30 to 40 kg/m2. Excluded were those with diagnosed diabetes, an acute coronary event in the past 6 months, pregnancy, polycystic ovary syndrome, major depression, previous bariatric surgeryor use of weight-loss medication, and eating disorders.
Participants randomized to the high-fiber group had a mean total dietary fiber intake of 19.1 g/day at 1 year.
The Institute of Medicine recommends daily fiber intake of 38 grams and 25 grams for men and women under age 50, respectively. For those over age 50, the recommendations are 30 grams for men and 21 grams for women.
The motivation for the study was to offer an effective alternative to the AHA dietary guidelines for cardiometabolic health, authors wrote. An intervention focused on a single dietary component could improve adherence.
The AHA goals include detailed consumption recommendations of vegetables and fruits, whole grains and fiber, animal and vegetable proteins, sugar, sodium, alcohol, and fat.
A landmark study published in the New England Journal of Medicine found that a weight reduction of 7% of initial body weight via lifestyle intervention was associated with a significant decrease in the incidence of diabetes.
But that study included a physical activity regimen in addition to a restricted diet, Ma noted. The current study did not address exercise so that diet could be the only factor assessed, he added.
Uncoupling diet and exercise may not be a clinically useful endeavor, cautioned George Blackburn, MD, PhD, associate director of the Division of Nutrition at Harvard Medical School in Boston, Mass., who was not involved in the study.
“This is hard work. There are no shortcuts,” Blackburn told MedPage Today. “You put nothing in, you get nothing out.”
Obesity guidelines from the American Heart Association, American College of Cardiology, and The Obesity Society recommend dietary changes as part of a comprehensive plan that includes physical activity and behavioral changes.
The study’s findings are not surprising, David Katz, MD, MPH, director of Yale’s Prevention Research Center, who was not associated with the study, told MedPage Today. “Get 30 grams of fiber a day served as a surrogate marker for ‘eat a variety of wholesome foods.'”
Participants received instructions on how to increase fiber intake or how to adhere to an AHA diet. Compliance was monitored by unannounced interviews with participants after 3 months, 6 months, and 1 year.
Weight loss at one year for the high-fiber and AHA diet groups was 2.1 kg (CI, 2.9 to 1.3 kg) and 2.7 kg (CI 3.5-2.0 kg), respectively. The mean between-group difference was 0.6 kg (CI minus 0.5-1.7 kg).
Participants in both groups decreased their total caloric intake, with greater reduction in the AHA diet group (200.0 kcal/d [CI 313.286.9 kcal/d] versus 464.6 kcal/d [CI 578.0- 351.2 kcal/d] in the high-fiber group).
After 1 year, the high-fiber group participants increased their dietary fiber by 4.7 g/day (CI 2.5-6.9), compared to 1.3 g/day in the AHA group (CI minus 0.9-3.5).
But the findings of this study may have less-than-desirable implications outside a clinical trial, Katz warned.
“My big worry here is that this another indication to repeat the follies of history,” he said. “If we now talk about just getting 30 grams of fiber, the food industry will be only too gleeful to produce a fiber-enriched inventory of junk food,” he said.
“When we talked about cutting fat, we didn’t eat more broccoli; we ate SnackWell cookies. When we talked about cutting carbs, we weren’t eating more wild salmon; we were eating low-carb brownies,” Katz added.
“I think it plays to a cultural appetite for magical thinking about diet,” Katz said. “I don’t think we’re serious about diet and health … we want to hear, ‘just tell us the one thing we need to focus on.'”
One study limitation was limited generalizability because the trial consisted mostly of well-educated white women with baseline fiber intake greater than the national average, authors wrote. Maintenance of weight loss after 1 year was not assessed.
Resources from AACE
Obesity Framework
The study received funding by the National Heart, Lung and Blood Institute.
The authors reported no disclosures.