Elderly are prone to gaining weight easily due to a slowdown in the body's basal metabolic rate.
It takes longer for the elderly to digest food as compared to the young.
Ageing leads to the lower secretion of certain digestive enzymes. Seniors also tend to be deficient in the micronutrient vitamin B12 unless on a supplement. Vitamin B12 requires acid in the stomach for absorption. And with age, the acid secretion decreases due to the withering of the acid-secreting cells. B12 is required to convert fat stores to energy, which is what helps one lose weight. Experts claim that lack of B12 leads to "stubborn fat".