Table 1.

Principal dietary restriction (DR) regimens.

Caloric restriction (CR)	Throughout the entire duration of the dietary intervention, participants have successfully implemented a reduction in caloric intake by 20–30% below the average, ensuring they maintain adequate nutrition and avoid any risk of malnutrition.
Intermittent fasting (IF)	Alternating periods of fasting and eating. IF includes: Time-restricted feeding (TRF): This IF regimen involves limiting the daily eating window to a specific time, typically 8–10 h, and fasting for the remaining 14–16 h. Alternate day fasting (ADF): ADF involves alternating between fasting days and regular eating days. On fasting days, calorie intake is severely restricted or completely avoided, while on eating days, individuals can consume their usual amount of food. Modified fasting: This approach involves reducing calorie intake on specific days of the week, often referred to as “fasting days,” while following a normal eating pattern on the remaining days. Typically, individuals consume a limited number of calories (e.g., 500–600 calories) on fasting days. 5:2 diet: This IF regimen involves eating normally for five days of the week and restricting calorie intake to around 500–600 calories on two non-consecutive fasting days. On the remaining days, individuals follow their regular eating patterns. Periodic fasting: Periodic fasting involves longer fasting periods ranging from 24 h to several days. For example, individuals may fast for 24 h once or twice a week or opt for longer fasting periods of 48 or 72 h intermittently.
Restriction of specific macronutrients	Glucose and carbohydrate restriction; Protein restriction; amino acid restriction; Micronutrient restriction.
Ketogenic diets (KD)	A high-fat, low-carbohydrate dietary approach that aims to induce a state of ketosis in the body. The typical macronutrient distribution involves consuming a very low amount of carbohydrates (generally less than 50 g per day or 5–10% of total calories), a moderate amount of protein, and a high proportion of dietary fat (70–75% of total calories).
Fasting mimicking diet (FMD)	A dietary protocol designed to mimic the effects of a prolonged fast providing some nutrient intake. The main components of an FMD typically include consuming plant-based foods such as vegetables, nuts, and seeds and healthy fats like olive oil. The macronutrient distribution is calculated to provide around 40–50% of normal calorie intake on the first day and around 10–20% for the following days of the fasting period (4–7 days every 15–365 days)