As part of the Nutrition for a Healthy Life study, participants were randomly assigned to one of four diets: high-fat omnivore (OHF), high-carbohydrate omnivore (OHC), high-fat semi-vegetarian (VHF), or high-carbohydrate semi-vegetarian (VHC).

While each diet provided the adequate amount of necessary energy from proteins daily, the source of these varied: omnivores obtained half of their protein requirements from animal sources, whereas semi-vegetarian plans provided 70% in the form of plant-based foods. To achieve the greatest homogeneity possible in the data, the 104 participants had a body mass index (BMI) between 20 and 35, were not smokers or vegetarians, and had no severe food allergies or chronic diseases.

Statistically speaking, the greatest improvement was observed in the OHC group, where the daily energy of individuals consisted of 28-29% fats and 53% carbohydrates, in addition to 14% proteins. In this group, where carbohydrates predominated, biological age was between 3.5 and 4 years younger than in the OHF group.

It is worth noting that the high-carbohydrate diets excluded refined sugars and/or ultra-processed foods, and that the macronutrient came mainly from complex carbohydrates (whole foods, rich in fiber and low in fat).

The results, although preliminary, suggest that short-term and not very drastic changes in diet could improve the body's response to stress, inflammation, and metabolic function.