Hi Salam, Well I don't know about tribulus but do look up ZMA and glutamine for increasing testostorone levels naturally....look 'em up on bodybuilding.com. I've used it b4 and the only side effect you might notice is some acne problems but all that goes away and there's no such thing as a free lunch. I'm not an expert but I don't think you can gain fat from these supplements. They have no sugar or useless calories...lemme know if that helps.