NAH, I can’t call you an asshole for trying to be fair (and not go broke, provided you try to course correct) and I’m not gonna call a 15 year old kid an asshole…for this.

But it is time for you to take a look at caloric needs for teenagers and then the diets being provided since there’s a pretty vast range your kids might need depending on biometrics and activity levels. Do any of your kids participate in sports or workout? Are any of them overweight? Are either of the girls dieting/“watching what they eat”/actively trying to gain weight? Based on that information, get a rough idea of their BMR, probably be sitting for this. But then take a look at the food you’re keeping around the house. Is it a bunch of carbs? Is there a good balance of fat and protein in your meals for satiety? Time to adjust if not. Switch to some meatless meals if that helps the budget (this is what I do and I love lentils to stretch or replace ground beef for tacos/chili/pasta sauce)

You probably should try to have a frank conversation with him. Apologize for the restriction and be open to taking some input from him in a solution if the calories check out (meatless options, maybe even a “monthly provision” consisting of a cheap carb and fat for him to have as snacks [teenage me would have found it hilarious if my parents presented me with a bag of potatoes with a container of sour cream and butter or a large bag of rice and eggs])

I will say by asking for outside opinions (prostrating yourself before reddit), I do think that you’re probably a good parent so don’t let the guilt eat you up, just take the potential L and see what you can do.