The increase in lifespan in the 20th century entails an increase in the elderly population. This brings a new challenge for society, causing people to have physical and mental limitations caused by age-related diseases, such as frailty. Frailty is clinically characterized by multisystem pathophysiological processes, such as chronic inflammation, immune activation, dysregulation of the musculoskeletal and endocrine systems, oxidative stress, energy imbalances, mitochondrial dysfunction, and sarcopenia. The elderly should consume energy in amounts close to those in what is currently accepted as a balanced diet. However, an increase in protein intake may be recommended for elderly people as long as there is no kidney damage. This increase could help fight the loss of muscle mass associated with age. Additionally, vitamin and mineral intakes are often insufficient in their diets. Therefore, the diet should be adapted not only to their age, but also to the pathologies associated with aging. Through these measures, we can reduce the prevalence of comorbidity and thereby increase health span. Therefore, both physical and nutritional interventions, including functional foods and nutraceuticals, should be taken into account.