Yes, if your body (skin) changes after you get a tattoo it can affect how it looks. My advice to you would be to talk to a tattoo artist about what you want and where you want it with regard to what could happen if your body changes. They could potentially advise you of what to avoid so that you don't end up with a weird/dumb looking tattoo.
Actually a well placed tatt in relation to the muscle negates the issue of tattoo distortion, because much of the issue is that the tattoo shifts as you grow, rather than entirely expands.
Mind you stretching will incur on steroids on the basis that you're in the gym for vast hours daily, but from what I've seen, negative space in the tattoo was made on the bicep, and he later inked that area in, the previous work was fine.
it might start to look disfigured and where its stretching it could look faded. sleeve would look good tho, maybe wait til you think that your at the right size then work out to keep that shape then get a sleeve
My brother got an eagle's head tattooed on his shoulder when he was 18. he probably gained 20 pounds since then. Today, 10 years later, the eagle looks drunk. I am not sure if it was the small amount of weight gain but it does seem that his skin has stretched in a way that the tattoo is distorted.