This plan is easy to follow if you can reduce your portions without getting frustrated. It doesn't matter what you eat (meals with or without sauce, fried food, sweetened, lean or full-fat food): your objective is just to eat less, and - crucially - to listen to your hunger! Here's a sample menu:
Breakfast: 1 hot drink + 30g bread + 10g butter + 10g jam + 1 piece of fruit + 1 yogourt.
Lunch: 1 main (100g meat or fish, 50g starch and 200g vegetables (or equivalent in a sandwich).
Dinner: 1 main with 125g meat or fish, 50g starch and 200g vegetables, 1 portion of dairy.