Hello sir, , After age if 60 Metabolic rate decrease due which many ppl gain weight. So , my opinion is that your Diet should be rich in those food which increase your metabolic rate. And if include those activity which make you stress free, activity should bring fun in life. And those activity which can increase your metabolic rate. If you a diet plan,you can contact me directly through the link below

Take high fiber low fat diet. Drink lot of water everyday. Take small and frequent meals at regular intervals of 2-3 hrs. Avoid outside food completely. Ask me directly for customized diet plan for you.