I did this by only changing one thing, as I consider the rest of my diet the healthiest for me and that is (ta da!) eating non-starchy vegetables for breakfast.
I don't know quite why this works, perhaps because they are low in calories (but I'm beginning to think that the whole calorie thing is a well propagated myth for women of a certain age!) or maybe because the body can continue to detox on them and still get nutrition (great nutrition as it happens if you choose your vegetables carefully).
Generally I saute some kale, courgette, green beans, mushrooms and broccoli or cauliflower and then pour my favourite no-oil home-made dressing over it.
I've been experimenting with using orange or grapefruit juice (just a bit) with soya milk, tomato juice, ketchup, mustard and balsamic vinegar. I love this dressing. And surprisingly the whole vegetables and dressing thing fills me up until lunch time depending on what I put into it.