Genes may not predict success of low-fat or low-carb diet

February 21, 2018 in Healthy Eating, Nutrition Topics in the News, Weight Management

Genes may not predict success of low-fat or low-carb diet

People who try to avoid junk food may lose similar amounts of weight on a low-carb or low-fat diet even when their genetics suggest that one of these options should be better for them, a new study from Stanford University in California has found.

Researchers randomly assigned 609 obese middle-aged adults to reduce carbs or fats in their diets for one year. Participants received 22 educational sessions focused on mindful eating and avoiding processed and sugary foods.

Researchers also looked to see whether participants had a particular genotype (a certain combination of the PPARG, ADRB2 and FABP2 genes) that some previous studies have linked to better results on either a low-fat or low-carb diet.

Diet followed, or genotype, didn’t make a difference

Weight loss over a year was not significantly different for overweight adults who followed a low-fat or low-carbohydrate diet, and neither a person's genetic makeup nor their insulin secretion level was associated with how much weight they lost.

At the end of the year, people on the low-fat diet lost an average of almost 12 pounds, compared with about 13 pounds for the low-carb diet.

The findings do not, however, close the door on the possibility that there are other genes that could be useful.

About the study

None of the study participants were told to cut calories. Instead of restricting carbs or fats by a prescribed amount, people were told to cut back by an amount that they felt was sustainable.

People were also encouraged to increase their intake of whole foods and vegetables and minimize added sugars and refined grains. To help curb mindless snacking, educators also told people to stop eating in their car or in front of their television and to make an effort to routinely dine with friends and family, shop at farmers’ markets and cook at home.

It’s possible this emphasis on healthy eating produced similar results with both diets tested in the study.

Eliminating refined grains, added sugars and increasing vegetable intake in both groups seems to suggest that steering individuals toward either a low-fat or low-carb diet is not as helpful as the diet quality.

Even though cutting calories wasn’t a goal for these dieters, people might still achieve this by replacing junk food with healthier alternatives.

One limitation of the study is that researchers relied on participants to accurately recall and report on what they ate and how much exercise they got.

It’s possible that the study failed to find a difference in weight loss with either diet based on genotypes at least in part because participants didn’t really follow the instructions for their assigned die, said some experts who were not involved in the study. Perhaps if they had implemented their assigned diet in a way that got the participants actually adhering to the diet recommendations, they would have shown what past studies show, which is that there are individual differences in response to different diets.

While more research is still needed on how a person’s genotype may affect their response to certain foods or diets, the results of this study and other research still point to one proven way for people to lose weight.

Source: JAMA, online February 20, 2018.

All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.