I think your mileage is going to vary based on your diet and when you eat, and your body's particular metabolic needs.

I have, through trial and error settled on a canteen of water when I first wake up, a cup of coffee, and then 3 hours later my 'breakfast' is a bowl of Greek yogurt.

I have little appetite the first couple hours of wakefulness even if I cut out coffee. Forcing myself to eat makes me feel slightly ill, and makes it more difficult to manage my caloric intake over the whole day.