Low-fat, plant-based diet compared to low-carb, animal-based diet in clinical trial – here are the results

People on low-fat, plant-based diets ate fewer calories per day, but had higher insulin and blood sugar levels, compared to when they ate a low-carb, high-protein diet. animals, according to a small, highly controlled study from the National Institutes of Health. Led by researchers from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), the study compared the effects of the two diets on calorie intake, hormone levels, body weight, and more. The results, published today (January 21, 2021) in Nature medicine, broaden understanding of the impact of restriction of carbohydrates or dietary fat on health.

“Foods high in fat are thought to lead to excessive calorie intake because they contain a lot of calories per bite. Alternatively, foods high in carbohydrates can cause large swings in blood sugar and insulin which can increase hunger and lead to overeating, ”said Kevin Hall, Ph.D., principal investigator of NIDDK, senior author of study. “Our study was designed to determine whether diets high in carbohydrates or fat lead to increased calorie intake.”

The researchers housed 20 adults without diabetes for four consecutive weeks in the metabolic clinical research unit at the NIH Clinical Center. The participants, 11 men and nine women, were given either a low-fat plant diet or a low-carbohydrate animal diet for two weeks, immediately followed by two weeks on 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 contained equivalent amounts of non-starchy vegetables. Participants were given three meals a day, plus snacks, and could eat as much as they wanted.

Examples of dinners given to study participants: low-carb, animal-based (left) and low-fat, plant-based diet (right). Credit: Amber Courville and Paule Joseph, NIH

The main results showed that people on a low fat diet consumed between 550 and 700 calories less per day than when they were on a low carbohydrate diet. Despite the large differences in calorie intake, participants reported no difference in hunger, meal enjoyment, or satiety between the two diets. Participants lost weight on both diets, but only the low-fat diet led to significant body fat loss.

“Despite eating a diet rich in high glycemic index carbohydrates which resulted in marked swings in blood sugar and insulin levels, people on plant-based, low-fat diets showed significant reductions in calorie intake and loss of body fat, which challenges the idea that high-carbohydrate diets per se lead people to overeat. On the other hand, the animal-based low-carb diet did not result in weight gain despite being high in fat, ”Hall said.

These results suggest that the factors that cause overeating and weight gain are more complex than the amount of carbohydrate or fat in the diet. For example, Hall’s lab showed in 2019 that a diet high in ultra-processed foods leads to overeating and weight gain compared to a low-processed diet that matches carbohydrates and fats.

The plant-based, low-fat diet contained 10.3% fat and 75.2% carbohydrates, while the animal-based, low-carbohydrate diet was 10% carbohydrate and 75.2% carbohydrate. 8% fat. Both diets contained about 14% protein and corresponded to the total number of calories presented to the subjects, although the low-carb diet contained twice as many calories per gram of food as the low-fat diet. On the low-fat menu, dinner might be a baked sweet potato, chickpeas, broccoli, and oranges, while a low-carb dinner might be beef stir-fry with rice. cauliflower. Subjects could eat whatever they chose and regardless of the quantity of meals they received.

“Interestingly, our results suggest benefits for both diets, at least in the short term. While the low-fat, plant-based diet helps reduce appetite, the low-carb, animal-based diet has resulted in lower and more stable insulin and glucose levels, ”Hall said. “We do not yet know if these differences would hold for the long term.”

The researchers note that the study was not designed to make dietary recommendations for weight loss, and the results may have been different if the participants were actively trying to lose weight. Additionally, all meals were prepared and provided to participants in a hospital setting, which can make results difficult to repeat outside of the lab, where factors such as food cost, food availability, and preparation constraints. meals can make it difficult to stick to diets. The tightly controlled clinical environment, however, ensured objective measurement of food intake and precision of data.

“To help us achieve good nutrition, rigorous science is essential – and of particular importance now, in light of the COVID-19[feminine pandémie, alors que nous visons à identifier des stratégies pour nous aider à rester en bonne santé », a déclaré le directeur du NIDDK, Griffin P. Rodgers, MD.

Référence: «Effet d’une alimentation végétale faible en gras par rapport à une alimentation cétogène d’origine animale sur l’apport énergétique ad libitum» par Kevin D. Hall, Juen Guo, Amber B. Courville, James Boring, Robert Brychta, Kong Y . Chen, Valérie 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 et Stephanie T. Chung, 21 janvier 2021, Médecine de la nature.
DOI: 10.1038 / s41591-020-01209-1

La recherche a été soutenue par le programme de recherche intra-muros NIDDK. Un soutien supplémentaire du NIH est venu de l’Institut national de recherche en sciences infirmières sous la subvention 1Z1ANR000035-01.