Background Aging is generally accompanied by changes in body composition, muscle mass and strength, leading to a decline in motor and functional performance. Physical activity and eating habits could be involved in modulating this paraphysiological deterioration. Aim of our study was to investigate changes in body composition, diet and physical performance in healthy, elderly females over a 3-year follow-up. Methods 92 healthy elderly females (70.9±4.0years) attending a twice-weekly mild fitness program were eligible for the study. They were assessed at baseline and again after 3years in terms of clinical history, diet, body composition by DEXA, resting energy expenditure, handgrip strength, knee extensor isometric/isotonic strength, and functional performance measured using the Short Physical Performance Battery (SPPB). Results After 3years, women had a significant decline in muscle strength (∆ isotonic: −1.4±4.3kg, ∆ isokinetic: −2.0±6.3kg, ∆ handgrip: −3.2±5.0kg; p<0.001) and physical performance (∆ walking time: 0.71±0.9s, ∆ walking speed: −0.25±0.35m/s; p<0.001), while their weight and body composition parameters did not change, except for a small decrease in appendicular skeletal muscle mass (−0.4±1.4kg). There was a significant drop in calorie (∆:−345.7±533.1kcal/d; p<0.001) and protein intake (∆:−0.14±0.23g/d; p<0.001), while resting energy expenditure remained stable. ∆ calorie intake correlated with the variation in 4-meter walking time (r: 0.34; p<0.01). Conclusions With advancing age, physical performance declines even in healthy, fit females despite a spare of weight and body composition. This decline in physical activity could lead to a lower calorie intake, which would explain why there is no variation in body weight.