Body Composition, Physical Function, and Dietary Patterns in People from 20 to Over 80 Years Old.

Objectives: Diet may influence biochemical pathways involved in age-related changes in body composition and physical function. This study aimed to describe dietary patterns and their relationships with body composition, physical performance, and grip strength according to age and sex.

Design: Cross-sectional study.

Setting: Data were collected in the Clinical Research Center (CRC) of the Gérontopôle of the Centre Hospitalier Universitaire (CHU) of Toulouse or at participants' homes when unable to attend the research facilities.

Participants: 470 (63% female) people with a median age of 56 (38 - 70) years.

Measurements: The "Mediterranean-like" (i.e., plant-based foods, dairy), "Animal products" (i.e., meat, processed meat, butter, refined starch), and "Sugar and fast food" (i.e., ultra-processed and sugary foods) dietary patterns were extracted by principal component analysis. Total and trunk fat mass indexes (kg/m²), and total and appendicular lean mass indexes (kg/m²) were assessed by DXA. The physical tests comprised gait speed (m/sec), chair rise (sec), the Short Physical Performance Battery test (/12 points), and handgrip strength (kg). The associations were explored through multivariate linear regressions by sex and age groups: ≥20 to <50, ≥50 to <65, and ≥65 years.

Results: Men and women had higher adherence to the "Sugar and fast food" diet in the youngest group. Middle-aged and older women adhered more to a "Mediterranean-like" diet. Men kept a "Sugar and fast food" diet when middle-aged and changed to the "Animal products" diet when ≥65 years. Higher adherence to the "Mediterranean-like" diet was associated with lower BMI, body fat, and lean mass in middle-aged men. Higher adherence to the "Animal products" diet was associated with higher lean mass in middle-aged women, more trunk fat in young men, lower strength in middle-aged men, and higher strength in older men. Higher adherence to the "Sugar and fast food" diet was associated with higher body fat in middle-aged men but lower body fat in older men.

Conclusion: Diets composed of sugary foods, fast foods, and processed meat were associated with higher fat mass and lower strength. Men were more prone to have less healthy food intake in all age groups.