Mollies are flat out PIGLETS

Mine see me walk by the tank and they practically jump out of the water to get at the "food lady." They beg and beg and beg some more. I stick my hand into the tank, and they chew on it, lol. They will pester you to death for food, and eat themselves to death if you let them.
A good rule is to feed all in one feeding that they can consume before it hits the bottom of the tank. Twice a day should be plenty.
That said, it could be they are acting extra voracious because their diet is lacking - one thing that a lot of people do not realize about mollies is that they are very much veggie eaters. They do need some protein, but their diet should be plant based, similar to goldfish. They would really love to have some algae wafers, green beans, peas, etc. at every meal. One of the benefits of feeding peas to your ballon mollies is that fish that have shortened bodies and "ballooned" stomachs are more susceptable to bloat and buoyancy issues, and the peas help to clean out thier systems. Also fast them one day a week to help them clean out too.
Feeding sinking foods can keep them from gulping a lot of air at the surface and getting excess gas in their tummies.
I purposely grow algae in my molly tank, because that is what they mainly eat in the wild, and they graze constantly, non stop on it.
Kristina