⇒ Is breakfast the most important meal of the day?
⇒ Does it jump start your metabolism?
⇒ Is it essential for fat loss?

Food = energy so logically speaking eating breakfast when you first wake up makes sense. You’d wanna eat food after being fasted state (sleeping) to have energy to go about your day.

When it comes to kick starting your metabolism studies show that there is no metabolic adaptations to eating breakfast vs not eating breakfast. However, the same study showed that people who eat breakfast burn more calories through physical activity thermogenesis.
(Betts et al, 2016) So from that an output standpoint, it would seem like a good idea to eat something after you wake to help you burn more calories through physical activity even though it has no affect on your RMR.

From an intake standpoint though we know that when it comes to fat loss and creating a caloric deficit that the best/ easiest way to do so is via nutrition.
Its MUCH easier to eat 200-300 less calories than it is to work it off in the gym (not that it works that quite way).
So if you are in a fat loss phase skipping breakfast can be a helpful strategy to reduce caloric intake.
The net energy balance is the overall driver of fat loss and being in a caloric deficit.

My recommendations:
⇒ When you eat and how much you eat at each feeding time is going to depend on YOUR personal preference, schedule and routine.
⇒ If you are physically or mentally active and have to perform in the hours after waking you'd probably benefit from eating some carbs and protein.
⇒ Eat and structure your meals in a way thats gonna help you perform the best in your day and support your lifestyle.
⇒ If you decide to skip breakfast you want to make sure your first meal of the day is high in protein and is nutrient dense to help balance your overall diet.

Eating breakfast is not essential for fat loss and there is not one “most important” meal of the day. It all comes down to the quantity and quality of the total calories consumed throughout the day, and not the time at which they’re consumed.