You don't have to buy anything. First cut out all refined sugar then start fasting (only water, black coffee/tea) regularly once a week (36 hours) and extend it

You don't have to buy anything. First cut out all refined sugar then start fasting (only water, black coffee/tea) regularly once a week (36 hours) and extend it to twice a week when you're comfortable with it. If you also want to improve your health generally, start walking. Weigh yourself first thing in the morning and write it down. Don't be concerned about daily fluctuations, but once a week calculate your weekly average. Use that to judge progress.