People on a low-fat, plant-based diet ate fewer daily calories but had higher insulin and blood glucose levels compared to when they ate a low-carbohydrate diet on animals, according to a small but highly controlled study at the National Institute 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, presented today (January 21, 2021) in Physical Medicine, broadens the understanding of how the restriction of carbohydrates or fats in the diet can affect health.
‘It is suspected that high fat foods result in excessive calorie intake because they contain many calories per bite. Alternatively, carbohydrate-rich foods can cause a large swing in blood glucose and insulin that can increase hunger and lead to overeating, ” said Kevin Hall, Ph.D., lead author of the study. “Our study was designed to determine whether carbohydrate or fat diets result in more calorie intake.”
The researchers housed 20 adults without diabetes for four consecutive homes in the NIH Clinical Center’s Metabolic Clinical Research Unit. The participants, 11 men and nine women, received a plant-based, low-fat diet or an animal-based, low-carbohydrate diet for two weeks, immediately followed by two weeks on the alternative diet. The low-fat diet contains a lot of carbohydrates. The low carb diet is high in fat. Both diets are minimally processed and have equal amounts of non-starchy vegetables. The participants received three meals a day, plus snacks, and were able to eat as much as they wanted.
The main results showed that people on a low-fat diet ate 550 to 700 fewer calories per day than when they ate the low-carbohydrate diet. Despite the large differences in caloric intake, participants reported no differences in hunger, meals, or fullness between the two diets. Participants lost weight on both diets, but only the low-fat diet resulted in a significant loss of body fat.
‘Despite eating foods with an abundance of high glycemic carbohydrates that led to a marked fluctuation in blood glucose and insulin, people who ate the low-fat plant-based diet had a significant decrease in calorie intake and loss. shown to body fat, which challenges the idea that carbohydrate diets in themselves cause people to eat. “On the other hand, the animal-based, low-carbohydrate diet did not result in weight gain, although it is high in fat,” said Hall.
These findings suggest that the factors that lead to overeating and weight gain are more complicated than the amount of carbohydrates or fat in your diet. For example, Hall’s laboratory showed in 2019 that a diet high in processed foods led to overeating and weight gain compared to a minimally processed diet similar to carbohydrates and fat.
The plant-based, low-fat diet contained 10.3% fat and 75.2% carbohydrate, while the animal-based, low-carbohydrate diet was 10% carbohydrates and 75.8% fat. Both diets contained approximately 14% protein and were consistent with 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, the dinner can consist of baked sweet potatoes, chickpeas, broccoli and oranges, while a low-carb dinner can be meat stir-fry with cauliflower rice. Subjects were able to eat and how many they chose from the meals.
“It is interesting that our findings have benefits for both diets, at least in the short term. “While the low-fat, plant-based diet helps curb appetite, the animal-based, low-carbohydrate diet has led to lower and more stable insulin and glucose levels,” Hall said. “We do not yet know whether these differences will persist in the long run.”
The researchers note that the study was not designed to make dietary recommendations for weight loss, and that the results could have been different if participants had actively tried to lose weight. Furthermore, all meals were prepared and provided to participants in an in-patient environment, which may make it difficult to replicate the results outside the laboratory, where factors such as food costs, food availability and restrictions on meal preparation may make it difficult to adhere to diets. However, the strictly controlled clinical environment ensures objective measurement of food intake and accuracy of data.
“To help us achieve good nutrition, strict science is critical – and now especially important in the light of the COVID-19 pandemic, as we seek to identify strategies to help us stay healthy, “said Griffin P. Rodgers, director of NIDDK, managing director. This study brings us closer to answering long-sought questions about how what we eat affects our health. “
Reference: “Effect of a plant-based, low-fat diet versus an animal-based, ketogenic diet on ad libitum 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, Shanna Yang and Stephanie T. Chung, January 21, 2021, Physical Medicine.
DOI: 10.1038 / s41591-020-01209-1
The research was supported by the NIDDK Intramural Research Program. Additional NIH support is from the National Institute for Nursing Research which gave 1Z1ANR000035-01.