Well if it’s weight you want then I would suggest protein supplement powders aligned with weights and just maybe more foods. I know that you are really healthy , but if you are going with an anti-cancer diet then you will be losing weight and will find it hard to retain it. Yes I’m at the other end of the camp and eat / drink what I want , but I’m still only 12 1/2 stone ! Creatine will build muscle but will only marginally add weight. You need carbs and protein and fat I think , which you may be avoiding. Stay well