I am not on a diet as such but eat fairly small amounts as I am tiny, old and put weight on easily.
My rough guide is:
Brekkie 1 or 2 eggs, scrambled boiled or poached with 1 slice toast or 2 oat cakes
Lunch - usually some kind of veg soup about 250mls (might be homemade or Yorkshire Provinder which is under 300 cals half a carton, ), or small piece cheese , an apple, or small tin tuna in water with green salad, or prawns and salad etc.
Some kind of fruit- apple, small banana, blueberries.
Dinner- portion of baked fish with roast veg ( peppers, sweet pots, ) herbs, and greens ( broccoli , spinach, green beans, carrots...) or roast chicken ( hot or cold), stir fry (no rice), homemade shepherds pie (I use venison mince- low in fat) , stuffed peppers ( stuff with a mix of Puy lentils and mushrooms) with a large salad,
Always have at least 100mls Greek yogurt a day with berries.
Snacks- walnuts, almond butter on apple slices or oat cakes.