There's a certain type of man who loves "big beautiful women." The rest of them require that you work out. Don't do it for any one man; do it for all men-- and yourself, of course. Many women end up as just an after-hour booty call-- and thus an afterthought-- because a man they like would rather see them face down with their gut disappeared into the mattress. If you escalate to a relationship and then get fat on him (without having any kids), it's safe to say he'll cheat on you with a skinny bitch. Skip the Spanx and get a gym membership. Be somebody he would want to show off and he'll be less inclined to treat you like a gargoyle.
Side Note for White Women: There's been a misunderstanding among you that if you're big with a fat ass you'll be accepted by black men. FAIL. They like "thick" women, those who look like could survive a few days without food, but they're not certified chubby chasers. And when they say "fat ass" they're referring to how your butt protrudes in profile, not how wide your hips are.