If eating food is what makes people gain weight, can you lose weight by not eating? This is a question a lot of people who are desperately trying to lose weight ask probably because it makes sense.
The short answer is, yes. Losing weight by not eating at all is a sure way to lose weight quickly, at least for the short term. If you’re planning on not eating to lose weight, you should first understand the basics of what will happen to you once you stop eating.
What Happens When You Starve Yourself?
Up to about 6 hours of not eating, it’ll be business as usual for most people. The body will have enough energy to do what it needs to do to keep you alive, alert, and functioning properly. During this time, your body’s main source of energy will be glucose. Your body does this by breaking down glycogen into glucose and then uses glucose as fuel to keep your body running.
From about 6 hours to around 72 hours, your body will go into a state of ketosis. When you body runs out of glucose from carbs for your cells to burn for energy, it goes after your fat. Your fat is broken down for energy and as a byproduct, ketones are produced. High levels of ketones aren’t good for you but since your body is in need of energy, it does what it has to do to survive.
This isn’t to say that being in this state is bad. Many people go into this state frequently especially those who workout for long periods of time. It’s when you stay in that state for way too long that issues start to occur.
At 72 hours, your body starts to break down protein by breaking down amino acids to turn into glucose to use as energy. This is when your body starts to go into cannibalism mode to survive. Your muscles start to break down making you lose some muscle mass.
At this stage, your metabolism decreases, your heart rate can decrease, your breathing might slow down, and even your temperature can drop. This is your body’s way of staying alive. It does this by conserving energy.
Mentally, you may start feeling irritable, have depressive symptoms, and experience a reduction in cognitive functions. These things can happen well before the 72 hour mark. Many people feel them within 8-16 hours.
If you’re not eating for a week or more, more serious problems can include permanent organ damage since your body starts to eat up 25-50% of your organ tissues. After your muscles are depleted for energy, your immune system will start breaking down.
Many people who starve themselves for way too long die of cardiac arrest since their heart doesn’t have the tissue or energy to function correctly. So rather than dying of starvation, they die of complications caused by starvation. Death can occur anytime from about 3 weeks to 70 days. It can happen sooner as well depending on the person’s weight, genetics, and other factors.
Here’s an infographic showing the different stages of starvation.
How Fast Can You Lose Weight By Not Eating
My guess is you only plan to not eat for a day or so and not go to the extremes and kill yourself. If that’s the case, the question then is how much weight can you lose by not eating? In the time frame of 1-3 days, you can lose anywhere from 1 to 5 pounds.
Now, much of this weight loss will be water loss. Some will be fat loss and some will be muscle loss. How much you lose will depend on a lot of things like how much you’ve been eating, how much you weigh, your metabolism, your level of activity and so on.
If you know what amount of calories you need to maintain your current weight, you can get a rough estimate of how much weight you will lose if you stop eating by knowing that 1 pound is roughly equal to 3,500 calories. So if you burn 1,800 calories a day, you need at least that much to keep your current weight. If you don’t eat, you’ll be at a 1,800 calorie deficit each day and after 3 days, you’ll be at -5400 calories which means you’ll lose about 1.5 pounds.
You’re likely to lose more since water isn’t factored in. By the way, you need to drink water. You can survive over 2 months without food but without water, you’ll be history in about 3 days.
At the end of day 3, you’ll be a few pounds lighter, weaker, probably moody, starving, and likely feeling sick. So now what? What most people do is they start to eat, a lot. This is what happens when you starve yourself. The result is you will likely gain all that weight back and even put on a few extra pounds since your metabolism is now a bit lower as well and you’re probably won’t be doing any exercises during this nutrient replenishing stage.
If you’re going to starve yourself, at least do it correctly.
How to Starve Yourself
Don’t eat, duh! But there’s more to that. You’ve already seen the negative effects not eating can do to your body and overall goal of losing weight in the long run so you should know that not eating for 3 days or 7 days is just a bad idea. But you also know that going a certain amount of time without eating food can force your body to start burning away your fat reserves.
Let me introduce you to Intermittent Fasting.
Fasting basically means you go a certain amount of time without eating. Extreme diets usually involve starving yourself. Intermittent fasting is NOT a diet. It’s basically a controlled way of getting your body to reach that stage where it goes after your fat.
The basic way it works is you limit the amount of hours to consume a whole day’s worth of food down to 4-8 hours. Most people sleep 8 hours and then have 16 hours to eat their daily meals. With intermittent fasting, you still eat the same amount of food but you eat all of it in a 4-8 hour window. The rest of the time is your fasting period where you don’t eat but still drink water of course.
Since sleeping counts are part of your fasting period, a typical schedule would be something like this:
10pm – 6am: Sleep
2pm – 10pm: Eat your meals
This means once you wake up, you can’t eat anything until 8 hours later. This assumes you choose the 8 hour eating window. Some fast an extra 4 hours and cram all their food within a 4 hour feeding window.
We all fast while we sleep but 8 hours is usually not enough time for your body to start hacking away at your fat. For most people, you’d have to go beyond 12 hours without food for that to happen which is why with Intermittent Fasting, you basically starve yourself for 16 hours before eating.
Notice the difference between this and just starving yourself. With intermittent fasting, you’re actually eating food.
To lose weight using this method of eating, figure out how many calories you burn each day by using this calculator, then reduce that number by about 500 calories and make that your daily calorie limit. From there, consume those calories within an 8 hour window while not eating anything during the rest of the time but still drink water, lots of it.
I personally did intermittent fasting for a couple of years and what I can say is it will be hard at first. You’ll be starving but you’ll get used to it to the point where it won’t be a big deal. You’ll have a hard time eating all that food. You might think eating isn’t a problem for you since you’re trying to lose weight but try cramming all that food down in half the time you usually do, it’s not easy. However, your body will adjust and you’ll be able to do it more easily as time goes on.
This type of eating may or may not work for you. Some people find it hard due to work and family. Although it’s effective, it’s not for everyone.
Here’s a short video talking about the benefits of intermittent fasting and a couple of different types of IF:
Don’t Lose Weight By Not Eating
Even if you’re just trying to lose weight in 3 days for some social event coming up, it’s just not worth it. Whatever you lose, you’ll likely end up gaining it all back since you can’t starve yourself forever. If you don’t eat, will you lose weight? As you’ve already seen, yes, but there’s a better way than just straight up starving yourself.
Say to yourself, “Starving myself isn’t worth it.”
You can lose weight by not eating but to keep it off, you need a much better, healthier plan. It takes discipline and consistency but the long term benefit is that once you reach your desired weight goal and maintain it, you won’t have to worry about dieting again.
But what if you need to lose weight right away and need something fast for now and promise to do it the right way afterward?
Fast Diet Recommendation
There are a lot of diets out there, some good, most of them bad. The key to successfully losing weight is to follow a diet you can stick with for more than just a few days or weeks. The best diets are ones that use a solid method based on science and aren’t too extreme.
A popular diet that many people have had good results with is the 3 Week Diet. You want to lose weight semi-fast and have the discipline to stick with the plan, then give that diet a try.