Fat experiences

How about you wait until you're ready.
first of all try to manage on financial for yourself and your bills If you barely have $100 to spare then that means you shouldn't do it as if it will be bad to you.

or just play it cheap.
don't buy food or support her
just encourage instead
as If she can support herself
or try home cook like pancakes and other things that ingrediants doesn't cost much

Noodles are almost free calories. Soft drinks and chips are almost free.

Buy a big bag of flour. Make your own pizza dought (super simple). Have bags of shredded cheese, pepperoni, and crumbled bacon in the house. Make your owan sauce or buy it even. For a few bucks you make a pizza that can blow delivery out of the water and certainly is better than the deep frozen stuff. Price per pizza is maybe 5 bucks tops.

Chicken is super cheap. Learn to make butter chicken, using real butter not the coconut milk recipes, and parmessan chicken. Both are simple, delicious, and you can boost calories as you see fit she should gain.

A good tip from @Bicepsual on this forum; buy tose SideKicks packages and sub the milk/water for heavy cream.

Learn how to make really nice sandiwches. 2 slices of bread, some olive oil, tomatoes, pastrami, cheese, some spices, "roast" in your oaster oven.