What is the best food for a cat to gain weigh after nursing kittens?

A mom cat and her kittens adopted my patio a little while ago, and naturally I've been trying to leave some food and water out for them as often as possible. The mom cat was very skinny so I have been feeding her extra foods packed with vitamins and fats, like chicken, special dry & canned cat food, turkey, some beef, and she LOVES biscuits and cheese! :) But she never seems to gain any weight. I want to make sure she is eating enough to produce milk for her kittens and remain healthy, but it doesn't seem to matter what food I give her. Any food recommendations for a nursing stray cat?

Also... If they stay around any longer, I will have to take them to the shelter but I'd rather give them to people who will provide a good home. I live in Dallas. Please inquire if you are interested!

DO NOT Give "milk milk milk" like the above answer states - cats are lactose intollerant. Give the mother small amounts of yoghurt & PROPER kitten milk (or goats milk - as it is lactose free) out for them.

Also, the mother might like some red meat (such as beef) minced & a raw egg in it.

You need to make sure the mother's diet is high in calcium so the kittens get the calcium through her milk to ensure they don't have low calcium levels and break their little legs a little while down the track

Also, if the mother is now very skinny & not putting weight on, it may be an idea to worm her with a worming treatment that is suitable for breast-feeding queens....as I live in a different country I don't know what is available where you are, and cannot help with brand suggestions.

Nursing mothers do best on (dry) kitten food as this has everything in it that the cat needs - vitamins, minerals, nutrients.

Have you wormed her? If not please do so as soon as possible, also de flea her.

Just make sure she has as much dry kitten food as she wants, plenty of water, is wormed, flead etc. Some minced meat will also be enjoyed by her.

milk, milk, milk. it's high in proteins and you don't have to worry about difficiency in fluid intake. it's all in there.

Mother cats do get thin while nursing. I always had good luck with Purina cat food - - my cat dearly loves the Kibbles 'N Bits cat food by Purina. Let mom eat as much as she wants.

Also, plenty of fresh water - - throw some ice cubes in which helps freshness & keep it cool.

We had a mom cat that got so weak from nursing that her legs was having trouble holding her thin body upright; mom needed help. So, we gave the kittens warm whole milk with an eye dropper once a day (twice if we could). A couple of weeks later, we tried to get them started on bread soaked in warm milk then soft kitten food chunks (in sealed bag). Giving mom plenty of food and helping fill the tummies of the kids, she started to gain weight & get her strength back. We had her spayed after that litter.