A new report showed that the traditional American Heart Association (AHA) diet found a match in the high-fiber diet, leading to approximately the same amount of weight loss after 1 year. However, author Yunsheng Ma, MD, PhD, of the University of Massachusetts, admitted that neither of the diet groups achieved the target of the study, which was to lose 7 percent of baseline body weight. A modest decrease in weight could be observed, ranging from 5 to 7 pounds in each group.
The trial enlisted 240 adults, aged between 21 and 70, and observed their dietary habits for a year. All of their metabolic syndrome and body masses indices showed 30 to 40 kg/m2. People were not accepted in the trial if they suffered from major depression, eating disorders, or if they had previous bariatric surgery or used weight-loss medication. Participants from the high-fiber group had a fiber intake target of 19.1 g/day for a year.
The Institute of Medicine suggests the consumption of 38 grams for men and 25 grams for women under the age 50. Over the age 50, experts recommend 30 grams for men and 21 grams for women. The authors conceived this study for the purpose of finding an alternative to the AHA guidelines for cardiometabolic health. Changing a single dietary component could encourage more people to adhere to the diet. As it is now, the AHA targets a recommended intake of vegetables and fruits, animal and vegetable protein, fiber and whole grains, sugar, alcohol, sodium and fat.
One of the most significant studies published on the subject in the New England Journal of Medicine reported that changing your lifestyle and losing 7 percent of initial body weight is connected with an important decrease in the risk of diabetes. The difference is that this study also regimented strict physical activity, not only specialized diet. Ma added that their current study did not take physical exercise into consideration, and that their only factor to be assessed it diet.
Separating diet and exercise is not useful in a clinical trial, as explained by George Blackburn, MD, PhD, associate director of the Division of Nutrition at Harvard Medical School, who did not take part in the study. Conducting such a trial is hard work, and you have to make sure you put all the necessary data in, if you want to get accurate results out of it.
Dr. Blackburn’s point of view receives great support from the obesity guidelines set by many health authorities: the American College of Cardiology, the American Heart Association, and The Obesity Society, they all recommend that changing your diet should be accompanied by a plan that includes a physical activity program.
David Katz, MD, MPH, director of Yale’s Prevention Research Center, said that the study’s results are not surprising, explaining that eating 30 grams of fiber a day falls in the guideline of “eating a variety of wholesome foods”.
At the beginning of the study, the participants were instructed on how to expand their intake of fibers, or on how to follow the AHA diet, depending on the group they were in. Researchers checked in on them at regular intervals of 3 months, 6 months and 1 year, but their interviews were always unannounced.
At the one year milestone, the group following the high-fiber diet showed a 2.1 kg weight loss, and the AHA diet group – 2.7 kg, resulting in a tiny gap of group difference of 0.6 kg. Both groups were encouraged to decrease their caloric consumption, but the AHA diet group managed to win this round, reducing it to 200 kcal/d versus 464 kcal/d. At the end of the study, the volunteers from the high-fiber group raised their fiber intake by 4.7 g/day, whereas the ones in the AHA group – 1.3 g/day.
However, Dr. Katz is worried about the unpleasant implications of the study’s result outside this clinical trial. If experts start talking about increasing our daily intake of fibers with 30 grams, the food industry will quickly react by producing a whole new fiber-enriched range of junk food. Whenever health experts talked about cutting fat, the reaction wasn’t to eat more broccoli; people started eating SnackWell cookies. Is the carbs were the issue next, our diets didn’t include more salmon; instead, we started eating low-carb brownies.
This situation has happened before; let’s just think about the First Lady’s health movement “Let’s Move”. When experts agreed that high intake of sugar was one of the leading causes of obesity, the food industry quickly replied by making bite-sized junk food, instead of taking their harmful products off the shelves.
Katz stated that the general problem is the magical thinking on diet that culture imposes on us. We don’t want to change our lifestyles; we just want to know what is that one thing that will magically help us lose weight.
Even this new study had its limitations, given by the fact that the participant base was mostly made up of well-educated white women, whose baseline fiber intake is greater than the national average. The study did not follow up on the maintenance of weight loss after 1 year.
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