Hope my answer doesn’t get buried and I hope you don’t feel too overwhelmed by all the responses you’re getting. But something I found really useful is frozen veg. If you’re struggling to plan healthier meals that are higher calorie, frozen veg is a game changer. It doesn’t go bad, it’s cheaper than the fresh stuff, and the most important thing is you can add it to your existing diet. I have a soft spot for ramen and box mac and cheese for example, and it’s so easy just to throw handfuls of whatever I’ve got in the freezer into a pot of pasta or ramen to make it just a bit healthier. Hell, you can even forget the ramen altogether and just use the soup base (it’s just stock!) to make lazy soup. Add a chopped onion if you’re feeling fancy and that’s that.

You also list a lot of protein sources that you can’t afford to add to your diet. Protein is a necessary nutrient, but it’s not the end all to a healthy diet. I say that as a lifelong athlete. It’s very easy to get an appropriate amount of protein from plant based sources, and they tend to be a lot cheaper. Plus, they tend to be higher in other macros and nutrients. Soy milk, for example, has the same protein content as dairy milk (but might be more expensive depending on your area). Beans and other legumes are fantastic and tasty. Chickpeas are my favourite. If you have a blender or food processor, you can make hummus very easily. Lentils are also amazing if you are able to cook. Cheap as hell if you buy them in bulk and insanely filling. Indian dhaal is a lentil stew that’s fairly easy to make and very tasty. If you can afford it, snack on nuts and seeds. Add peanut butter (look at labels to find some that doesn’t have sugar in it) to your diet. Both those things are higher in calorie while also being high in nutrients. If you eat rice, try getting brown rice instead of white rice. It’s higher in protein and fiber and will likely keep you full for longer. Potatoes and other root vegetables are also awesome. Versatile, cheap, relatively high calorie, easy to cook, and keep for a long time if stored properly. I like to make a huge pot of potato stew with beans and frozen vegetables and keep it in the fridge for easy meals for like a week. If you’re looking for animal protein, check your local grocery for frozen fish. Its usually half the price of the fresh stuff.

I’m not your doctor, but personally, 800-1000 cal/day was terrible for my health. Yeah, it’ll make you lose weight, but for me it made me really lethargic and gave me brain fog. It just wasn’t enough to keep my body going. Maybe try slowly lowering your calorie intake and see how your body feels. I’ve also found that in the past, calorie counting was actually counterproductive to my health because what ended up happening was it became a “game” to eat fewer and fewer calories a day. Luckily I saw that and stopped counting calories before it turned into an eating disorder. My point here is just that it’ll take some work figuring out what works for you and don’t get discouraged if a method doesn’t fit your body or your lifestyle.

In terms of exercise, I know it’s not a satisfying answer, but it’s really going to depend on your body and what type of exercise you’re doing. If you’re exercising, you should definitely be eating more than 800-1000 cal/day unless you’re like, a toddler. It’s dangerous in my non-professional opinion to exercise when you’re under eating by that amount particularly if you’re lifting weights or doing high impact cardio.

I wish you luck on your journey and I hope it all works out for you :)