It is observed that when obese people lose weight your body decreases the metabolic rate in an attempt to retrieve it again (a process that remains years), after which the organism returns to normal basal metabolism, to accept the new weight as appropriate.

The daily energy expenditure decreases progressively throughout adult life. In sedentary individuals, the primary determinant of energy expenditure is fat-free mass, which declines by about 15% between 30 and 80 years, contributing to a basal metabolic rate lower in older adults. Creatinine excretion in 24 hours (an index of muscle mass) is closely related to the proportion of basal metabolism of all ages. Nutritional surveys in those over 65 years show a very low energy intake in men (1400 kcal / d; 23kcal/kg/d). These data indicate that preservation of muscle mass and prevention of sarcopenia can help prevent the decline in the rate of metabolism