Replacing Animal Products With Plant-Based Foods Leads to Weight Loss in People With Type 1 Diabetes, Finds New Research

WASHINGTON, D.C.—Replacing animal products with plant-based foods—even those defined as “unhealthy” by the plant-based diet index—is an effective strategy for weight loss in adults with type 1 diabetes, finds a new study by the Physicians Committee for Responsible Medicine published in Frontiers in Nutrition. Participants following a vegan diet lost 11 pounds on average, compared to no significant weight loss for participants following a portion-controlled diet.

“Our research shows that replacing animal products with plant-based foods—even so-called ‘unhealthy’ ones, as defined by the plant-based diet index—benefits people with type 1 diabetes who are looking to lose weight,” says Hana Kahleova, MD, PhD, director of clinical research at the Physicians Committee for Responsible Medicine and lead author of the study. “Whether you have an orange and oatmeal for breakfast or orange juice and toasted white bread, either option is a better choice for weight loss than eggs and cottage cheese.”

The new research is a secondary analysis of a Physicians Committee study, which was the first randomized clinical trial to look at a vegan diet in people with type 1 diabetes. In the 12-week study, 58 adults with type 1 diabetes were randomly assigned to either a low-fat vegan group with no limits on calories or carbohydrates, or a portion-controlled group that reduced daily calorie intake for overweight participants and kept carbohydrate intake stable over time.

In this secondary analysis, participants’ dietary records were used to assess the relationship of a plant-based diet index (PDI), healthful PDI (hPDI), and unhealthful PDI (uPDI) with weight loss in adults with type 1 diabetes. “Healthful” plant-based foods, as defined by the PDI system, include fruits, vegetables, whole grains, nuts, legumes, oils, coffee, and tea. “Unhealthful” plant-based foods include fruit juice, sugar-sweetened beverages, refined grains, potatoes, and sweets. In each of the categories, a higher score indicates greater consumption of the plant-based foods in that category.

In the study, the overall PDI score increased on the vegan diet, and did not change on the portion-controlled diet; the hPDI score increased on both diets, more on the vegan diet; and uPDI increased on the vegan diet, and did not change on the portion-controlled diet.

Participants on the vegan diet significantly increased consumption of “healthful” plant foods including legumes, whole grains, and fruits, while consumption of vegetable oils and nuts significantly decreased; on the portion-controlled diet, participants increased their intake of whole grains. Consumption of “unhealthful” plant foods did not change significantly on either diet, except for reduced consumption of refined grains on the portion-controlled diet.

Participants on the vegan diet lost 5.2 kilograms (about 11 pounds) on average, which was associated with changes in PDI and hPDI scores, while there was no weight change for participants on the portion-controlled diet. Changes in uPDI did not result in changes in weight.

The original study found that a vegan diet also reduced insulin needs, improved insulin sensitivity and glycemic control, and led to improvements in cholesterol levels and kidney function in people with type 1 diabetes.