I know that you should eat breakfast to get your metabolism started, but what is enough? A handful of cereal? A cup of tea?
Great question! Let's start with the basics.
We all have what is known as a basal metabolic rate (BMR), which reflects how rapidly our bodies burn calories through a variety of biochemical processes.
Our metabolism is never turned off. Even while you sleep, your metabolism is up and running.
If you are looking to lose weight, you want to increase your BMR so your body is able to burn more calories.
How do you do this? The best way is by engaging in physical activity.
Why? The more muscle mass you have, the higher your BMR.
There's more. When you starve your body, it has no idea when its next meal will be.
If you go a whole day consuming only 800 calories, your body doesn’t know you are doing that on purpose. It thinks you are in shortage of food and in fear of starvation! So, it goes into self-preservation mode and slows everything down in order to store energy, including your BMR.
Similarly, if your last bite of food is at 10 PM and you wake up at 8 AM the next day, that's a ten hour period where your body's metabolic state is in fasting mode (hence the word breakfast, literally meaning "breaking the fast").
This is why diets very low in calories are counter-productive to weight loss in the longrun.
See, once your BMR slows down and you go back to your regular way of eating, you will very likely gain weight, since your BMR needs to warm up from its mini-vacation before it can kick into high gear and burn calories as effectively as before.
There isn't a specific quantity of food needed to get your metabolism up and running. Even gulping down a glass of orange juice as you rush out the door in the morning is better than starting your day off on an empty stomach.
Additionally, skipping breakfast is an easy way to end up overeating at lunch or stopping by your office's vending machine at 11 AM for a "quick pick me up", often in the form of a King Size Snicker's bar.