”How Fast Can You Lose Weight By Not Eating…” (Mind Blowing Details You Didn’t Know)


Have you ever wondered? How fast can you lose weight by not eating for some time? You are in the right place!

We gain weight for many reasons, including genetics, metabolism, hormones, stress, sleep deprivation, etc. But the most crucial reason is our diet. We simply aren’t eating healthy enough nutritious foods, and we’re not exercising enough.

In this article, I’ll explain how fast you can lose fat by reducing your calorie intake. And I’ll also tell you why you shouldn’t try to cut calories as quickly as possible.

If you are overweight? If you struggle with weight loss? Or if you are considering losing weight by not eating? Then you should read this article!

How Fast Can You Lose Weight By Not Eating?

I can answer this in a few sentences. You can lose 6-8 pounds per week if you don’t eat at all, depending on factors like your initial body fat percentage and overall body composition. However, a lot of that weight loss will be the loss of water weight.

Is it healthy to not eat at all for more extended periods than, say, 2-3 days? HELL NO!

I always say that you don’t have to starve yourself if you want to lose weight. At least not longer than a couple of hours or even days. Just like anything in life, fitness or learning a new skill, etc… Think long-term. It will be more maintainable, realistic, and in many cases, more healthy and fun.

A more realistic and healthier objective could be losing 1-2% of your body fat per week. More than 2% per week is excessive and not maintainable for the many reasons I will explain in this article.


What Exactly Happens With Your Body If you don’t Eat?

It’s hard to believe people can survive without eating or drinking for days or weeks. A few days of fasting or even a few hours of not eating and drinking can leave some of us feeling cranky and lacking energy.

If you’re fasting or not eating for long periods, your body will adjust by slowing down its metabolism. It allows people to engage in fasting diets like the eat-and-stop-eat approach (or intermittent fasting) without causing irreversible damage to their bodies.

Your body needs at least eight hours without eating to use fat instead of sugar as its primary energy source. Before that, it works as if you were eating normally.

Typically, your body converts food into glucose. Glucose gives the body energy.

When the body doesn’t have access to food for 8-12 hours, its glucose storage is emptied. As soon as your body begins converting glycogen from your liver into glucose, your blood sugar levels will rise, and you will start to feel tired.

When your glucose and glycogen stores run out, your body will start using amino acids to help supply energy instead. This process will cause your muscles to shrink, and it may take up to three days of fasting before your metabolism shifts into survival mode.

To avoid losing too much muscle mass, the body uses its fat reserves to produce ketones for energy, called ketosis. During this period, you will lose a lot of weight.

The more fat stores a person has, the longer they can survive without eating for an extended period. After the fat has been completely burned off, the body turns to muscle breakdown for energy because no other available fuel sources are left.

During this starvation phase of your body using muscles for energy, you may feel some unpleasant side effects, including headaches, dizziness, irritability, fatigue, etc.

A study in the BMJ (British Medical Journal) found that people without eating for days may suffer from serious health complications if they lose more than 10% of their body weight. It also states that if someone loses 18% of their body weight, they could be at risk for severe health issues.


The Health Benefits of Short-Term Fasting

Fasting isn’t just about losing weight; it’s about being healthier overall. A healthy diet includes plenty of fruits and vegetables, whole grains, nuts, legumes, fish, and lean meat. But what happens when we go without food for days at a time?

Autophagy is a cellular recycling program that allows the body to clean itself out. When we eat, our digestive systems break down the food into smaller bits and send those nutrients to our cells. Our bodies are constantly making energy, repairing tissues, and eliminating waste.

When we don’t eat for extended periods, our bodies use autophagy to help clear away damaged parts of the body. Autophagy is essential in maintaining health. Scientists call it “cellular housekeeping.”

In recent years, researchers have been studying how fasting affects the human body. They’ve found intermittent fasting improves insulin sensitivity, reduces inflammation, increases longevity, and boosts immunity.


How to Fast Safely

I’ve been reading books on fasting lately because I want to start experimenting with it.

There are even books saying that you should avoid taking supplements during fasting. A book called “The Miracle Morning” thinks you shouldn’t eat breakfast. Another says you should drink only distilled water while fasting.

So what am I supposed to do?

To answer this question, we have to understand what happens when you fast. When you skip eating for extended periods, your body goes into survival mode and conserves energy.

This is why fasting is sometimes referred to as “starvation mode.” During starvation mode, your metabolism slows down, and your body becomes more efficient at burning fat. Your brain also shuts off hunger signals, making it easier to resist cravings.

In addition to slowing down your metabolism, fasting causes your liver to release stored glycogen (stored glucose). Glycogen is sugar that your body stores up for times when you need extra fuel.

If you eat carbs after fasting, your body converts them into glucose and uses them as fuel, which makes sense because you just burned all the calories stored inside your liver. 

How Much Weight Will I Lose on a Juice Fast?

The idea behind juice fasting is pretty simple: skip solid foods altogether and drink only juices for some time. It might sound like a great way to go if you want to lose weight fast. However, there are some things you need to know about juice fasting before you decide whether or not it’s worth trying out.

Juice fasting isn’t a diet; it’s simply skipping meals. This doesn’t mean you don’t eat anything else during the day. Instead, you consume water, tea, coffee, broth, fruit drinks, smoothies, sports drinks, soups, broths, and even vegetable juices.

Some people add supplements to help make up for what they aren’t consuming, while others stick to water alone.

While juice fasting does allow you to cut calories, it’s important to note that you still need to eat something every meal.

Otherwise, you could lose muscle mass, making you look thinner but putting you at risk of developing health problems.

Also, if you don’t eat enough throughout the day, you won’t feel full and may overeat later. I might sound like a broken record, but although juice fasting allows you to drop pounds quickly, it can cause weight gain once you start eating again.

How Weight Loss Works

Weight loss is pretty straightforward: Eat less food than you expend, and you’ll lose weight. But there’s a lot more going on behind the scenes of this caloric intake concept.

Your body works hard to maintain homeostasis — balance —and it does so by regulating temperature, breathing, heart rate, blood pressure, hormones, metabolism, fluid levels, and many other functions.

If you eat too little, your body responds by slowing down some processes, such as digestion and respiration, and speeding up others, like hormone production and energy storage.

But what happens if you don’t eat enough? In that case, your body starts shutting down specific systems and prioritizing others. This is called catabolism, and it’s how your body breaks down muscle and organ tissue to release stored energy.

The problem is that your body doesn’t know whether you’ve been eating enough, so it adjusts accordingly.

For example, your body might start breaking down muscles to generate energy when you don’t eat enough.

But if you eat plenty of carbs later, your body will store the extra sugar as glycogen in your liver and muscles, and insulin levels will rise.

So even though you ate fewer calories overall, your body thinks you ate more because you didn’t consume enough carbohydrates.

This is why losing weight requires cutting both calories and carbs. Cutting back on your calorie intake without reducing carb consumption leads to ketosis, a metabolic state where your body burns fat rather than carbs for fuel.

And while a low-carb diet can lead to rapid weight loss, it can also cause fatigue, headaches, constipation, and brain fog. In general, it will have a negative influence on your activity level.

Short-Term Fasting Diet

A crash diet is one where people drastically reduce food intake over a relatively short period.

A typical example is a three-day cleanse, during which you eat nothing but water and broth and drink coffee enemas to flush out toxins. Some people even go as far as drinking salt water.

Celebrities often use crash diets as part of their fitness regimen, though they don’t typically lead to lasting weight loss and will, in most cases, even lead to weight gain.

Crash diets aren’t recommended because they can make losing weight harder. While you might lose some weight initially, you’ll likely regain it later. You could end up fatter than you were before.

You could use a two or 3-day crash diet to transition into your regular diet, like hitting the ground while running.

The reason is simple: while you’re starving yourself, your body starts burning off stored fat for fuel. This process takes a lot of energy, making it difficult to burn enough calories to keep up with your eating. Plus, without the proper nutrients, your body can’t function properly.

Your best bet is to take things slowly. Instead of cutting out entire food groups, try gradually reducing portions. If you want to cut carbs, start by swapping half of your pasta for beans or swapping half of your bread for veggies. Make sure you’re still getting plenty of protein, too.


Longer-Term Fasting Diet (My Recommendation)

Time-restricted fasting (16:8)

This is, for me, the best diet (way of eating) you can follow to feel and look great. I’ve tried plenty of diets throughout my life, and Intermittent Fasting is the diet I love.

It’s easy to implement and maintain. In the 16:8 Intermittent Fasting Plan, you choose a daily eating window, which should leave you with a 16-hour fasting period.

You might consider increasing fat cell metabolism and optimizing blood sugar levels.

You set your eating window from nine a.m. to five p.m., for example.

Fasting is so much of the time spent sleeping anyway. It also depends on how consistent you’re able to be.

Daily periods of fasting may not be ideal for everyone. If your schedule is often shifting or you want the flexibility to eat at various times throughout the day, daily fasts may not suit you.

Symptoms When You Stop Eating Too Long

Your body will burn fat at an increased rate after several days or weeks. You will also lose some muscle mass. When you don’t eat enough, your body enters starvation mode, breaking down muscle tissue for energy.

When you’re low on energy, your body slows down or shuts off certain body parts.

Backed up by researchers at Livestrong, these symptoms may include:

  • Gastrointestinal distress
  • Feeling cold all the time
  • Depression
  • Anxiety
  • Fainting
  • Loss of menstruation
  • Hair loss
  • Dental erosion and dental pain
  • Dry skin
  • Brittle bones
  • Dry, brittle nails
  • Hair thinning and hair loss
  • Swelling around the salivary glands
  • Growth of fine hair on the body
  • Poor wound healing
  • Frequent infections

The Main Problem With Losing Weight Too Fast.

Quick-fix diets aren’t the best way to lose weight sustainably; they usually backfire and will launch your Yo-Yo dieting journey.

You may lose 10 pounds quickly by following, for example, a liquid cleansing or some other fad diet, but drinking beet and lemon juice for an extended period isn’t healthy.

After a week or so, you will return to eating normally again, and your body will return to its original weight. 

Quick diets are tough to maintain. Fortunately, most of us live where food is always available, so we need to learn how to use it properly. It means creating permanent dietary and behavioral changes that fit your life, culture, and food preferences.

You’re designed to go back to your original weight. It will do everything in its power to increase your appetite so that you can gain weight again. If you lose weight too quickly, your body doesn’t have enough time to adapt.

However, slow weight loss allows your body time to reset itself. It’s a sign that you’re making doable changes for yourself to sustain in the long run. Finding a balanced diet that works for you is the key.

Nutrient Deficiencies From Fasting

Many people think fasting is about skipping meals, but it’s much more complicated.

A healthy diet includes adequate protein, carbohydrates, fats, vitamins, and minerals. When you don’t eat for prolonged periods, your body breaks down proteins into amino acids.

These amino acids are used to build new tissue and repair damaged tissue, but they’re also required for energy production. If there aren’t enough amino acids, your body starts breaking down fat stores to generate energy.

Your immune system becomes compromised without sufficient nutrients like zinc, magnesium, copper, and selenium.

You start to feel tired and weak, and you might even develop cold sores. In addition, your skin loses elasticity, and wrinkles begin to form.

Better Way to Weight Loss

Starving yourself to lose weight is detrimental to your physical and mental well-being. While you may lose fat and appear thinner, the rest of your appearance will suffer when you lose muscle tone, and your skin and hair become dry and brittle.

You can achieve the weight-loss results you want and feel and look healthy by eating a balanced, calorie-sufficient diet that provides all the nutrients you need.

Cutting out processed foods that are high in calories and low in nutrients and replacing them with fresh, nutrient-dense foods will help you create enough of a calorie deficit to shed fat.

Eating enough lean protein will help you maintain muscle mass as you lose weight, and complex carbohydrates from fruits, vegetables, and whole grains will give you the energy to boost your physical activity to burn calories and build muscle.


Easy Diet Tips To Eat Healthy Without Starving Yourself

  • Portion Size… First, take a hard look at your portion sizes. Just halving this aspect will already save you calories you might be overindulging.
  • What do you consume? Secondly, take another hard look at what you consume daily. Make a food journal if you need, but start making healthy choices. Avoid junk food, substitute fatty meats for veggies or rice, and create tasty options that won’t make you feel like you’re even on a diet. Remember, healthy foods can taste nice too.
  • Cut Sugar and Soda from your diet. You’ll lose 5 lbs a week just by cutting out sugar drinks/sodas. In a month, that’s 20 lbs. over just stopping soda.
  • Fluids… You need to keep hydrated, but using water as an appetite suppressant helps as well. When you feel the snack urge hit, drink some cold water. It will help at least pass the cravings until your next meal.
  • Exercise. You should start a daily, low-impact exercise regime. This will not only help increase your metabolism but also help with energy, cravings, and even depression and anxiety.
  • I would read up on “Ketosis” and see the options here; they will quickly help you lose 30 or more lbs without starving yourself.
  • 16:8 Intermittent Fasting. My personal favorite. (Did you know that you can combine your Intermittent Fasting with a Keto Diet and a Low-Carb Diet)


Honestly, I would never recommend not eating for more extended periods…

First off, You’ll be setting yourself up for failure. After 2-3 days, you’ll probably be hungry for carbohydrates and protein, which means you’re more likely to eat something unhealthy if you don’t get enough calories from healthy sources.

A side note: Find friends who share your passion for working out and eating well. If you have a supportive network, you’ll be motivated to keep going and get some encouragement from them when you reach your goals. You’ll also find plenty of similar advice from others who share your experiences.

By binging and purging on a calorie-deficit diet, you will not only slow your metabolism, but your stomach will store the food if it’s your last chance to eat for a while.

So not only are your hungry, angry, and frustra­ted, but you’re going to make it harder for yourself to be active, reach your weight loss goals, or maintain a healthy weight, for that matter.

The best advice I can give is to think of it as a lifestyle change and not a diet and that you’ll succeed and achieve long-term weight loss. As soon as you start thinking of something as a limitation, you’re already beginning to set yourself up for failure.

Thanks for reading, and good luck on your journey.

If you have any comments or questions, please leave them in the comment section below.

Stay Healthy and Strong!


Meet Ezra, a former model and actor turned founder of GymTrends365. His no-BS approach to fitness helps men over 40 achieve their best shape. Ezra believes in empowering individuals to take control of their health and fitness through practical, sustainable methods. At GymTrends365, he's committed to providing the resources and support necessary to help everyone achieve their fitness goals.