If you starve yourself, your body stores fat and relies on it to keep you alive. If you eat (but eat healthy foods) your body does not need to store fat as a reserve and can burn it more easily. In addition, if you starve yourself, your metabolism becomes less efficient, and that's why many people pile the weight back on after they've starved themselves. The best way to optimise your metabolism is to eat smaller meals and eat more frequently, but only healthy, smaller things. Starving yourself is 100% inefficient unless you're planning to starve yourself until you die.