The book that helped me change my metabolism was The New Fit or Fat, by Covert Bailey. I was surprised at how gently I needed to exercise to keep it aerobic, rather than exercising beyond 60-85% of my maximum heart rate and having it become anaerobic exercise. Exercising in the 60-85% range is what burns fat, and above that builds muscle (but doesn't do much to burn fat). It's surprisingly easy to overexercise, and build muscle but not change metabolism and lose fat.

He's all about decreasing fat consumption, which can only be stored as fat; and aerobic exercise that changes metabolism, so we burn fat (and everything else) more efficiently. I dropped 30 pounds over the course of a year walking ala Covert Bailey. Am taking up cycling to alternate with walking, and looking forward to long adventures on a new road bike soon. The good thing is, it's a lifestyle change: reducing fat consumption, increasing aerobic exercise, something I can keep doing and feel good at, rather than a diet I suck at sometimes, and gain weight back again when I go off.

Just what is working for me!