food ideas

I recommend home cooking with lots of vegetables.

I made a chilli last night with 3 onions (391g), 1 head of celery (431g), 4 carrots (370g), 3 cloves garlic (18g), 500g lean ground beef, a handful of green chillies (20g), 16g ground cumin, 800g tinned tomatoes, pack of runner beans (185g), 7g ground coriander, 3 bell peppers (249g) and 30g cilantro.

makes 8 generous bowls full at 216 calories a portion.
I appreciate this isn't calorie free, but it's pretty low cal for a main meal.

Put as many vegetables as possible into your meals to make them look like more food for your calories (I like my meals to look big) and make sure there's some protein in there too to keep you full for a while.

There are many, many options. You can take almost any soup, stew or chili recipe and add tons of vegetables like celery, carrots, green peppers. It will add volume and make you feel fuller with minimum extra calories. I enjoy adding fruit (apples, blueberries, strawberries) to my 1% fat cottage cheese in the morning. I use lower fat cottage cheese because I like to save my fat allotment for a tablespoon of good quality herb infused olive oil over my roasted vegetables (cauliflower, broccoli, or assorted root veggies). You can do this but don't over restrict.

Now there's a start. There's a huge difference between lower calorie foods and zero calorie foods. What do you usually eat? Because, not to be rude, but you can eat a ton of food on 2100 calories. So either you need to eat less, or you need to make better choices. But for the latter point, it would help to know what you're eating now.

If you want to add me as a friend, you can see my log. I work with 1740 calories a day which would give you an extra 360 to work with. You can see how I eat my calories and get ideas for what might work for you.