Aging produces several changes in body composition. Aging is associated with an increase in body fat and changes in their distribution pattern. The risks associated with an increase in body fat or from low weight are different in the elderly. As a result, the World Health Organization recommends a modification in the Body Mass Index (BMI) in the elderly. The BMI cutoffs currently used to assess the nutritional status of the elderly are: underweight (BMI <22kg/m2), normal weight (BMI between 22 and 27kg/ m2) and overweight (BMI> 27kg/m2). The prevalence of many complications associated with obesity-such as hypertension, diabetes mellitus, cardiovascular disease, some cancers, sleep apnea/hypopnea syndrome and osteoarthritis-also increases during the aging process. However, several studies have shown that overweight in elderly patients is not associated with increased mortality. Studies show that overweight reduces all-cause mortality among the elderly. This reduction is a paradox that contradicts evidences for other age groups. It should be noted, however, that sarcopenia associated with lower weight accounts for this increase in mortality. In obese patients a worrying picture is, therefore, the development of sarcopenic obesity. We thus conclude that weight control in the elderly has many peculiarities. Overweight is beneficial for the elderly, hence the adjustment in BMI values. Recognizing and managing comorbid conditions directly related to weight excess, at the same time, avoiding involuntary weight changes should be a priority in the care of the elderly.