You have choices. You can have a full breakfast, or you can have cereal or toast or whatever is on offer.
Being on IOT is different. You're tired for a start. Breakfast is the most important meal you have and you'll be more active than you have been, so don't think you can have a cup of coffee and a slice of toast.
Let's put it this way. Cereal and cooked breakfast in the morning. 2 course lunch. 3 course dinner. Still lost weight.
It's fuel and you need quite a lot at the time.