A year here in the IF... from my experience the Basal Metabolism can be altered in a more or less significant way but not in IF because is an Hypocalloric diet and your MEtabolic rate is going down while you are in one... if you want to increse your protein intake maybe try different sources till you find one that your body assimilates more than others... the flora in your gut play a major role in this so maybe you need to check that... I take an Inulin suplemment and a prebiotic that really helps... also Omega 3 oil is a helper here...