What happens to your body when it has no calories left?

Well your first energy source is carbs. A calorie is just a unit of measurement so if you ran out of calories nothing really happens. so it all has to do with how much carbs was in that cookie. Once that is burned off you use your stored fat which turns to Ketones by your liver and kidneys then you pee that out. Once most of your fat sores are used up your body breaks down muscle and eventually it will give out and die since you will have used up all the fat soluble vitamins and minerals, which means these are stored in your fat and released over time and all your protein stores. Some examples are vitamins A, E, D and K and an example of a mineral is iron.

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Holy **** you don't burn your muscle first!!!!!!!. Your body wants to use the easiest energy to burn and fat is easier than muscle to break down. Also the orphan example is of a bloated stomach due to the rice expanding that they eat. It's not fat.

Alright well for starters, "calories" is just another word for "energy". So when you "run out of" calories, you would feel drained and tired which would force your body to go into starvation mode where it breaks down anything it can in your body to get you up and running. Secondly, "being hungry" is a mental state. There are three stages to hunger- the first part is when you see food and you want some. You start salivating and this is the first step. The second part is when food enters the digestive system and starts making it's way through the esophagus and stomach and everything. Finally, the food reaches the intestines where the final stage occurs, and all of the "leftovers" that your body doesn't need leave the body. So if you want to get technical, when you are hungry, it is all mental until you enter the starvation mode (which takes a lot of time and practically no food to enter into.) Once you enter starvation mode, your body starts stealing nutrients from other organs in your body, once it runs out of necessary nutrients (which would be a HUGE problem for whoever is going through this) the body then starts to rid the body of fats. If you are asking this because you are intending to do it, please reconsider. It is extremely unhealthy and will make you EXTREMELY ill.

Hunger has more to do with hormones your brain produces telling you to eat. So...no. You don't get hungry when you eat all your calories. Sometimes people who have plenty of calories left feel hunger.

When you eat a 10 calorie cookie, and exercise let's say 20 calories, you body will draw from the energy storage to get energy (fat). If your pushing yourself to hard that it cannot get enough energy from your fat, it will start to burn muscle as well.

3,500 calories= 1 pound. So, when you have burned 3,500 more calories then you have consumed, you lose a pound. If you eat 3,500 more calories then you burn, you gain a pound.

But- it's not that simple. There are different things you can do to speed up the burning of calories, and slow down the burning of calories. (Metabolism)

Examples things that slow down metabolism which will take it longer to burn calories: eating less than 1200 calories a day, eating bad carbs such as sugar, not exercising.

calories don't relate to hunger. eating a large 300 calorie salad would fill you up more than a 300 calorie cookie! its estimated that when you lose weight, you lose 75% fat and 25% muscle.

Yes you will feel hungry.

Your body will burn off muscle first as it will be the most easily accessible form of food. That means your body will start to break down the muscle and you WILL get weaker. If you do see pictures of starving children, usually they have a big bulge in their stomach but their entire body is a stick.

They get stored as fat. 3500 calories in excess adds 1 pound of fat. Obviously this accumulates ovetime, unless you were to take 3500 + calories in one day

your body starts to digest itself to get nutrients, which is why you can die of hunger, although it takes a while