Lifestyle tips

Remain in a good condition. Take the stairs, take walks, all that good stuff.

Eat well. Don't ignore fruits and vegetables.

Play the long game. Instead of these explosion gains, just go for steady gaining. Adding half a lbs every 2 weeks still has you add 20+ lbs a year.

Health risks from various sources kind of multiply. So also try to limit your non fat related risks. Don't smoke, don't drink heavily. Get enough sleep. Take care of your teeth. Address any other health issues. Eat plenty of veggies and some fruit. Try not to sit for prolonged periods on a regular basis. Raise your heart rate regularly.

You can limit your risks from gaining by doing it smart, but you can't eliminate them. But by not burdening your body with other stresses, it will hopefully hold up better.