Diets notoriously fail to help people lose a lot of weight. One problem is that most diets include a broad range of restrictions and guidelines that many people find difficult to follow. Another problem is that negative recommendations may have unintended consequences, such as low-fat recommendations leading to increased consumption of refined carbohydrates. Now a new study published in the Annals of Internal Medicine indicates that a radically simple diet containing only one positive rule — eat more fiber — might be nearly as effective and much easier to swallow than a more traditional complex diet.
Researchers randomized 240 adults with metabolic syndrome in Worcester, MA to the multicomponent American Heart Association (AHA) diet or a very simple diet that focused solely on increasing the amount of fiber in the diet to at least 30 grams per day.
After one year there was no significant difference between the two groups in weight loss, though weight loss was modest in both groups: 2.1 kg in the high-fiber group and 2.7 kg in the AHA diet group. In both groups the authors found additional modest improvements in blood pressure, dietary quality, and insulin resistance.
Over the course of the year 9.9% of people in the high-fiber group and 12.6% of people in the AHA diet group dropped out of the study. Seven people in the high-fiber group and one person in the AHA-diet group developed diabetes (p=0.066).
The authors noted that in the U.S. people now consume only 16 g of fiber each day and only 7.1% of adults between 40-59 years old consume 30 g or more per day.
An Annals patient summary concluded that “a simpler approach to diet that emphasizes only an increase in dietary fiber might be a reasonable alternative for people who do not want or are unable to make more complicated dietary changes.”
Responding to the study on behalf of the AHA, Alice Lichtenstein pointed out that the AHA diet “is not particularly hard to follow, as demonstrated in the new study by the response of the subjects following the AHA diet compared to the high fiber diet. They did just as well or better.”
Lichtenstein also explained why the AHA does not think it’s a good idea to focus on a single dietary component: “whether it be carbs or fat, the basics sound good but in the end we have unanticipated consequences. Remember low-carb brownies and pizza and fat-free cookies and ice cream? The same concern exists for fiber. We already have fiber added to foods that don’t normally contain high levels such as yogurt, chips, and waffles, many of which are also high in sugar. Were we to go back to focusing on a single component I could see a repeat of the low-carb and -fat diets, only with fiber-supplemented foods.”
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