1) Marriage is more beneficial to women than men in terms of material benefit.
2) Being in the gym everyday is hard work.
3) Those women that let themselves go mainly worked out for attention instead of a desire to stay fit.
These women get the financial security of a man providing for them and if he doesn't like it, she can divorce him and waltz out, take half and then get a free income stream. No need to go to the gym when she's hit that financial security jack pot and feels she no longer has 'no-one to impress'. You know who will work harder at NOT letting themselves go? Women that married a rich guy with a pre-nup. Look at Pilar Sanders.
It's best to get a woman who is naturally skinny or who just loves fitness for fitness sake and not trying to catch a man. The latter is best, because even skinny girls can blow up.