As a physical energy source, bodyfat can be compared to one of those electrical powerbanks you use as a reserve for your mobile phone or tablet: a store of energy for when you need it. When you reduce food consumption your bodyfat store will start delivering, but it's important to get the balance right. A calorie deficit and a low insulin environment is a reasonable approach, but vegetables providing fibre and water won't hold back the process of weight reduction, and will do you good. Bear in mind also that the brain uses a lot of energy, and doesn't draw down from bodyfat — so check carefully when embarking on a weight loss strategy.