People on a low-fat, plant-based diet eat fewer daily calories but have higher levels of insulin and blood glucose than when eating a low-carbohydrate, animal-based diet, according to a small but highly controlled study at the National Institutes of Health. Led by researchers from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the study compares the effects of the two diets on calorie intake, hormone levels, body weight and more. The findings published today (January 21
“It is believed that foods high in fat lead to excess calorie intake, as they have a lot of calories per bite. Alternatively, foods high in carbohydrates can cause major changes in blood glucose and insulin, which can increase hunger and lead to overeating, “said Kevin Hall, a senior researcher at NIDDK, PhD, lead author of the study. “Our study is designed to determine whether diets high in carbohydrates or fats lead to higher calorie intake.”
The researchers placed 20 adults without diabetes for four consecutive weeks at the Clinical Center for Clinical Trials at the NIH Clinical Center. Participants, 11 men and nine women, received either a plant-based low-fat diet or a low-carbohydrate diet of animal origin for two weeks, immediately followed by two weeks of an alternative diet. The low-fat diet was high in carbohydrates. The low carb diet was high in fat. Both diets were minimally processed and had equivalent amounts of starch-free vegetables. Participants received three meals a day, plus snacks and could eat as much as they wanted.
The main results show that people on a low-fat diet eat 550 to 700 calories less per day than when they eat a low-carb diet. Despite the large differences in calorie intake, participants reported no difference in hunger, eating pleasure, or fullness between the two diets. Participants lost weight on both diets, but only the low-fat diet resulted in significant body fat loss.
“Although they eat foods high in high glycemic carbohydrates, which lead to marked changes in blood glucose and insulin, people who eat a low-fat plant-based diet show significant reductions in calorie intake and body fat loss, which is disputed. the idea that high-carbohydrate diets alone lead people to overeat. “On the other hand, a low-carbohydrate diet based on animals did not lead to weight gain, although it was high in fat,” Hall said.
These findings suggest that the factors that lead to overeating and weight gain are more complex than the amount of carbohydrates or fats in the diet. For example, Hall’s laboratory showed in 2019 that a diet high in processed foods leads to overeating and weight gain compared to a minimally processed diet consistent with carbohydrates and fats.
The low-fat plant-based diet contains 10.3% fat and 75.2% carbohydrates, while the low-carb diet of animal origin contains 10% carbohydrates and 75.8% fat. Both diets contained about 14% protein and were compared for the total calories presented to the subjects, although the low-carbohydrate diet had twice as many calories per gram of food as the low-fat diet. On the low-fat menu, dinner may consist of roasted sweet potatoes, chickpeas, broccoli and oranges, while a low-carb dinner may be beef with cauliflower rice. Subjects can eat whatever and however much they choose from the meals they have been given.
“Interestingly, our findings suggest benefits for both diets, at least in the short term. “While a low-fat plant-based diet helps curb appetite, a low-carb diet of animal origin has resulted in lower and more stable insulin and glucose levels,” Hall said. “We still don’t know if these differences will persist in the long run.”
The researchers note that the study is not intended to provide recommendations for a weight loss diet and the results may be different if participants are actively trying to lose weight. In addition, all meals were prepared and provided to participants in an inpatient setting, which may make it difficult to replicate results outside the laboratory, where factors such as food costs, food availability, and cooking restrictions can make dieting challenging. However, a strictly controlled clinical environment provides an objective measurement of food intake and accuracy of the data.
“To help us achieve good nutrition, rigorous science is crucial – and especially important now, in the light of COVID-19 pandemic, as we seek to identify strategies to help us stay healthy, ”said NIDDK Director Griffin P. Rodgers, PhD.“ This study brings us closer to answering long-sought questions about how what we eat, affects our health. “
Reference: “Effect of a low-fat plant-based diet on a ketogenic diet of animal origin on libite energy intake” by Kevin D. Hall, Juen Guo, Amber B. Courville, James Boring, Robert Brychta, Kong Y Chen Valerie Darcey, Ciaran G. Forde, Ahmed M. Gharib, Isabelle Gallagher, Rebecca Howard, Paule V. Joseph, Lauren Milley, Ronald Ouwerkerk, Klaudia Raisinger, Irene Rozga, Alex Schick, Michael Stagliano, Stephan Torres, Mary Walter, Peter Walter , Shana Yang and Stephanie T. Chung, January 21, 2021, Natural medicine.
DOI: 10.1038 / s41591-020-01209-1
The study is supported by the NIDDK Internal Research Program. Additional support from the NIH came from the National Institute for Nurse Research under grant 1Z1ANR000035-01.