Maybe anecdotal evidence work for me in this case. I cycle to work and back every day when the weather allows it (13 km one way) and I still use some of the same expensive clothes I wore 20 years ago. They still fit. And I eat a lot.
Maybe the answer is moderate excercise and books don't need to be sold about it? Just cycle along. It works for me.
It's strange, isn't it? The answer is so simple. An average of 15 minutes strenuous exercise a day. Don't over-excercise; don't under-excercise. That's about it. You can eat or drink everything you would like. Just get off your behind for at least 15 minutes a day.