Great question! There are a couple of ways to perform a butt augmentation, but the safest way with least complications that actually provide a modest result is with a brazilian butt lift - which is basically liposuction to harvest fatty tissue to be injected into the buttock. However, looking at your photo, you are athletic with minimal fatty tissue. Understand that with fat transfer, anywhere from 25-50% will not survive - so with the minimal amount that could be removed from your body, know that a good amount of it will not last over the long term. I do not feel it is possible to obtain your goal with the amount of fatty tissue you have. But you will still have some results, it just won't be very prominent.As far as gaining weight is concerned, I do not recommend gaining weight unless you plan on keeping it. Although weight gain will allow the surgeon to harvest more fat and provide more volume to your buttock at the time of procedure, often times patients end up loosing the weight after surgery because they do not like how big their face and other part of the body have become. Understand that with any weight loss, the volume of the buttock will also decrease. So in the short term, your results maybe spectacular, but in the long run if you end up loosing the gained weight, your buttock will shrink and all you would have done is stretch out the skin.Best of luck and hope this information helps!- Dr. Roger Tsai @DrRogerTsai