During old age, due to decline in functional capacity of body organs, people have weight loss especially because gastric acidity and motility is reduced which reduces the absorption of nutrients in the body. Generally people lose weight as they age due to loss of muscle mass and bone mass related to ageing. It is a natural process and nothing much can be done except to eat as healthy as possible and stay active throughout the day. Try to get adequate sleep as lack of sound sleep also increases physical stress leading to weight loss. Has your appetite decreased of late or are you having any gastric problem/digestion related problem? Are you feeling weak or lethargic alongwith losing weight? If you are having any medical issues or any other symptoms such as physical weakness, lethargy or fatigue alongwith weight loss, then you need to consult a physician.