The pills are not good for fasting, they will certainly effect your chances of getting into full ketosis and having a successful fast. If you take the pills you will not truly be fasting and risk starving your body of any fuel that you are not supplying it with, and no pill can replace full nutrition. So the only safe way to fast is with water (according to thirst) only.
Your age is certainly no barrier to fasting. Your size probably isn't either- it doesn't matter how big your waist is but how much stores your body has and how effciently it can use them. The habit of hunger can be beaten, it just takes perserverence. After a few days most people report the hunger goes. I personally find that eating a nice fruit salad the night before gives me a feeling of satisfaction that can last for the first couple of days of the fast at least and I often find these initial days the easiest so you might want to try that.