What Happens to Your Body When You Stop Eating?

By now, you know what you should be eating — plenty of fruits and veggies, lots of whole grains, and enough to meet the 2,000 calorie range, depending on your lifestyle. Some people, however, don’t get nearly this amount. Socioeconomic factors often come into play, as some families can’t always afford to have food on the table. Or, as we’ve seen in Netflix’s new film To the Bone, eating disorders can also lead to nutrient deficiencies.

You’ve probably wondered what your body goes through when you stop eating, though we in no way condone your attempt to find out. It’s OK — you don’t need to do your own home experiment. We’re here to tell you what would happen if all sustenance was suddenly removed from your life.

First six hours — everything is A-OK

Hungry woman holding a knife and a fork while at a restaurant

No one likes being hangry, but you’ll live through six hours without food. | iStock.com/beer5020

You might feel like you’re ravenous after six hours of not eating, but don’t worry — you’re totally fine. Science Alert explains that in the first six hours of going without food, your body busily breaks down glycogen, which is essentially a storage center for energy. From the glycogen break down comes glucose, which helps to power your brain, muscle tissue, and red blood cells.

Right around that six hour mark is when you’ll start to feel that cloying hunger. This is because your glycogen stores start to run out. Being “hangry” is often the result of your brain not getting enough energy to make the best decisions. The next time you’re hungry enough to bite your friend’s arm off, feel free to blame it on this process.

Six hours to 72 hours — entering ketosis

woman saying no to bread while drinking tea at a restaurant

If you’ve tried the keto diet, you’re familiar with the concept of ketosis. | iStock.com/lolostock

Your body can’t run on glycogen stores forever. Between six and 72 hours, you’ll be entering ketosis. Medical Daily explains ketone bodies are used for energy when your glycogen stores totally run out. This means you’ll be using excess fat stores as a main source of energy.

That doesn’t sound so bad to most people — and some even try the keto diet, which involves putting your body into this fat-burning state by purposely avoiding sugars and carbs. But surviving on ketone bodies alone can impair your mental function quite a bit. And once you’re 72 hours without food, things get really dire.

After 72 hours — protein breakdown

Tired businesswoman putting her head down at her desk

Expect a lot of mental fogginess if you go 72 hours without eating. | iStock.com/Poike

If you’re past 72 hours, you’ll be feeling weak, groggy, and unable to complete everyday tasks. Your mood will take a serious nosedive, as your brain starts to break down the proteins in your body, ScienceABC explains.

Here’s the thing about ketosis — your brain can’t actually use ketone bodies for energy. So, your brain being the smart organ that it is, it figures out another way to get its energy — by breaking down proteins. The amino acids that proteins release can be converted to glucose for the brain. But don’t expect to look your best after 72 hours of not eating. This protein break down will result in muscle loss and overall weakness. And women will experience a total shutdown of their menstrual cycle.

After one week — immune system shut down

a sick woman coughing in her bed with sheets around her shoulders

Your immune system takes a serious hit when you starve. | iStock.com/samotrebizan

Things are really all downhill from here. By now, you’ll have experienced a lot of weight loss in the form of fluids, muscle, and fat, and your body will actually start to adapt to conserve the protein that’s left, Medical Daily explains. Your metabolism will also slow to a snail’s pace to use as little energy as possible. And after a week, you’ll be missing a lot of vitamins and minerals, too, resulting in a compromised immune system. This is around the time you’ll be a lot more likely to get sick.

Three weeks — starvation

Doctor drawing a heartbeat chart with a red pen

Your heart takes the biggest hit when you’re not getting any nutrients. | iStock.com/BrianAJackson

It takes about three weeks for your body to totally shut down from starvation. Lacking nutrients for this length of time has dire consequences, which include tooth decay, weakened bones, and hair loss, Livestrong.com notes. Your organs also start to shut down in this final stage due to lack of nutrients, which, as you can imagine, is extremely bad for the heart.

So, how do you die from starvation? Dr. Robert Sullivan of Duke University Medical Center explains your body starts to leech protein from the heart, which can result in an irregular heartbeat and cardiac arrest, the Los Angeles Times reports. Aside from the heart being affected, extreme malnutrition alone can kill you.

Eating again after a period of starvation

a doctor taking care of a young woman in the hospital

You should be under a doctor’s supervision after a long period of starvation. | iStock.com/KatarzynaBialasiewicz

Let’s say you’re in a position where you have no access to food for a few weeks, but then the situation suddenly changes. Unfortunately, diving right into old eating habits after entering starvation mode can result in death. Emily T. Troscianko, a writer for Psychology Today who previously dealt with anorexia, explains what happens during “refeeding syndrome.” Basically, when you start to eat after a long period of starvation, your levels of electrolytes plummet. Having too little phosphate in the blood can cause delirium, muscle weakness, or even cardiac arrest when food is reintroduced.

Luckily, doctors know the best way to combat refeeding syndrome. Many people who enter the hospital after not eating for an extended length of time are given phosphorus supplements and fed higher volumes of food very gradually. Avoiding foods high in sugar can also help.

Starvation on a global scale

A teenager sitting on the floor of her bathroom looking at the scale

Millions deal with eating disorders in the U.S. | iStock.com/Highwaystarz-Photography

You’re probably lucky enough to live in a country where starvation isn’t super prevalent. But globally, it’s still a huge concern. World Hunger Education Service reports wars in Yemen, Nigeria, and Sudan as well as droughts in East Africa have caused huge agricultural issues, resulting in millions starving. Back in 2011, Somalia’s famine killed 260,000 people. And many people living in war-torn areas are dependent on emergency aid for their next meal, which certainly isn’t enough.

The U.S. doesn’t face these same issues, but another battle ensues — eating disorders. U.S. News and World Report says there are about 10 million Americans who have potentially life-threatening eating disorders. Scarily enough, these conditions are one of the leading killers of young women. Remember: Whether you’re dealing with one of these disorders yourself or you know someone who is, you can always reach out to the NEDA Helpline for support.