Fact Checked

What is Starvation Ketosis?

Amanda Piontek
Amanda Piontek

Starvation ketosis is a metabolic state in humans and many animals in which the body breaks down fat and produces acids known as ketones, then uses these as a primary energy source. The “starvation” part of the name owes to the fact that, in most cases, people only use ketones for energy when they aren’t getting adequate glucose from food. The body typically converts carbohydrates to glucose as a main source of energy, but once the liver has used all of its stored glucose it begins to metabolize fatty acids, forming ketone bodies. Malnutrition and fasting are two of the most common causes, but it can also be the result of conditions like diabetes, alcoholism, and a low carbohydrate diet. People sometimes intentionally trigger this state as a means of burning fat to lose weight, but whether this practice is safe or even advisable is widely disputed in the medical community. Ketones are capable of supplying energy to the body, but an abnormally high level can cause a number of problems, including organ damage, coma, and even death.

Understanding Ketones

The conversion of fat into ketones occurs in the liver.
The conversion of fat into ketones occurs in the liver.

The liver typically makes ketones in response to some sort of energy crisis in the body. People generally get the majority of their energy by synthesizing glucose, which is a sugar molecule found in carbohydrates like bread and grain products. When people aren’t getting enough glucose, the liver begins creating ketones that the body uses in combination with any fat stores it has on hand. Ketones in many ways prevent the body from robbing muscles of their core proteins. Starvation ketosis happens when these become the body’s primary source of energy.

Diabetes can interfere with the liver's metabolic process causing ketosis.
Diabetes can interfere with the liver's metabolic process causing ketosis.

The condition can usually be identified by looking for excesses. The body gets rid of unneeded supplies by spilling them out through exhalations, urine, and sweat. When this happens people often get sweet smelling, fruity breath that could be mistaken for the smell of alcohol. The odor might also be noticed in perspiration that is sometimes said to smell like ammonia, and urine tests can usually detect it, too.

What Causes Starvation

Alcoholism can cause starvation ketosis.
Alcoholism can cause starvation ketosis.

There are a few conditions and situations that can result in this state. Prolonged fasting, a severely calorie-restricted diet, and eating disorders can all deplete stored glucose. Diseases such as alcoholism and diabetes can also interfere with normal metabolism and can in some cases prevent the body from properly breaking down sugar even if it’s present. In addition, many low-carbohydrate diets are specifically designed to use ketosis to metabolize fat and cause the dieter to shed excess or unwanted weight.

Impacts and Effects

When fatty acids are broken down in the body, ketones are formed.
When fatty acids are broken down in the body, ketones are formed.

Short periods of starvation ketosis are usually fine from a health perspective, and in fact the mechanism is one that the body uses as a sort of temporary stop-gap. It’s not usually a good idea for people to rely on ketone energy for the long term, though. When the condition is extreme or unmonitored it can result in ketoacidosis, a disorder in which ketones can reach abnormally high levels that are dangerous or life threatening. People suffering from this often experience organ damage and brain swelling, which in some cases can lead to coma and eventual death.

Dispute About Safety

Ketones are capable of supplying energy to the body, but an abnormally high level can cause a number of problems, including organ damage, coma, and even death.
Ketones are capable of supplying energy to the body, but an abnormally high level can cause a number of problems, including organ damage, coma, and even death.

A number of nutritional experts and health practitioners recommend extreme “low-carb” diets that essentially force the body into a state of starvation ketosis as a means of losing weight. This strategy is very controversial in the medical community. Some experts say that limiting or eliminating carbohydrates, one of the body’s primary sources of glucose energy, forces better efficiency, while others counter that this is an abuse of the body’s “emergency” plans that can lead to bigger health complications later on. Anyone considering a low-carb plan for weight loss is generally advised to talk with a medical provider first to discuss the risks and benefits.

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Discussion Comments


Explain exactly what those essential carbs are? Our bodies need glucose, but the body can produce what it needs. I have never seed the essential carb list. Carbs > glucose > increase insulin > turns on fat storage.

No carbs can turn off fat storage causing weight loss without a reduction in food. I found the more fat I eat the more satiated I am, causing less food intake. I just eat until I am full. One gram of fat has nine calories, where carbs and protein only have four. Ketoacidosis is a concern for poorly maintained diabetics. In ketosis, your body takes weeks to convert to burning fat instead of glucose. Most people quit before this stage is over -- sad. It's worth the wait while your body gets off carbs and starts burning fat for primary fuel (three weeks on average). Most people store a maximum of only ~200 grams of glucose and an almost unlimited amount of fat. Which seems to be the primary source of energy? I think we have it backward.

This is why athletes eating carbs bonk after a few hours and people not eating carbs can keep going. 200 carbs just doesn't last long. It's like a car using a tank of unleaded (fat) but having nitrous (carbs) for a quick boost. Too much nitrous (carbs) will burn out the engine parts. Much like carbs do in humans (think diabetes). Carbohydrate is 100 percent anti-ketogenic due to its effects on blood glucose and insulin (raising both). Protein is approximately 46 percent ketogenic and 58 percent anti-ketogenic, due to the fact that over half of ingested protein is converted to glucose, raising insulin. Fat is 90 percent ketogenic and ten percent anti-ketogenic, representing the small conversion of the glycerol portion of triglycerides to glucose.

Even if you don't eat carbs you are still getting glucose whether you need it or not. A low carb, high protein diet is not ketosis. Saturated fat has been blamed for everything bad for too many years. I use ~75 percent fat, ~20 percent protein and ~5 percent carbs (or less). In the end, just avoiding carbs as often as possible will show results in weight and blood work. It's sad we are so hooked on carbs.


If someone is starving, with no food, how long will they live with ketosis?


My boyfriend is a diabetic, and sometimes I notice he has really bad or strong smelling breath. Could that be ketosis at work? If it is, isn't that a really bad thing to be happening?

He takes care of his shots well enough, but he eats in a very uneven fashion. Pretty much he'll not eat all day, then eat once, then not eat for a long time again. I know for a diabetic that's not healthy, and now after reading this article, I'm kind of concerned that he might be in ketosis a lot and not know it.

Since too much ketosis can be damaging, I really want to know if the breath thing and his eating habits and diabetes could be related. Does anybody know?

Are the damaging effects of ketoacidosis, like brain swelling and organ damage, the same dire damaging effects people refer to when they talk about a diabetic maintaining too high or too low levels of blood sugars? Since diabetics are concerned with carbohydrates so much, I could see how the two serious medical problem descriptions might actually be one and the same.


@seHiro - Yep, you've got it right! Low carb diets use ketosis in a controlled way. Think of it kind of like prescription medication: in moderation, it's good for you and can help your body stay healthy, but if you overdose you can hurt yourself or even kill yourself.

If you can be responsible with prescription medication, you're responsible enough to use ketosis the right way. Just make sure you know how it works.

By the way, Somersizing keeps the dieter from staying in ketosis by allowing them to eat carbohydrates in separate meals from the proteins. So long as the foods are eaten a certain amount of hours apart, they don't combine and spike the insulin, so you don't gain weight.

Since extremely low carbohydrates are the main cause of ketosis, you might think this would make the low carb side of Somersizing dangerous.

It isn't. Even somebody who chooses to stick just to the low carb, high protein side of Somersizing -- like I prefer -- won't stay in ketosis or probably even get there in the first place, because unlike Atkins, Somersizing encourages eating a bunch of vegetables that contain natural carbohydrates.

Atkins limits carbs so much that they cut down even which veggies you can have to just a few at first to bring about ketosis. The strictness of Atkins is why I couldn't handle doing it, and chose Somersizing instead.


@popcorn - In my understanding, there is only one kind of ketosis, so yes, low carb diets that promise to get you into ketosis are talking about starvation ketosis. Ketosis plays a big part in the workings of the metabolism and weight loss efforts relating to it.

Diets that involve ketosis, at least the one that I have looked into extensively -- the Atkins diet -- utilize ways to protect the dieter from entering anything near ketoacidosis.

The Atkins diet starts by having an individual enter ketosis by severely limiting their carbohydrates, but it emphasizes that the dieter should only stay in the ketosis stage for a very limited about of time before starting to slowly add in more and more carbohydrates per day until they reach their optimal level for weight loss.

The Atkins diet is centered around the concept that everyone has a certain level of carbohydrates they can consume while still losing weight, and that if you go over that amount, you will gain instead. The diet does not and has never advocated staying in ketosis indefinitely.

Hope that sheds some light on how low carb diets do use the same kind of starvation ketosis as is discussed here, but in a safe and controlled way.


@Hawthorne - Low calorie eating is my preferred food lifestyle. During my teens I practiced the Somersizing way of eating, which is a low-carb diet developed by Suzanne Somers and based on the French traditions of eating carbohydrates and fats separately.

Somersizing is based around the fact that without something that spikes your insulin levels, your body cannot turn the food it just ate into fat. Mixing carbs with protein spikes the insulin, and the whole meal goes to fat stores instead of being burnt -- kind of the anti version of ketosis weight loss.

If you keep your different food types separate, though, the insulin won't spike, and you will burn the food as energy instead of storing it as fat.

With Somersizing, you can choose to eat a mostly carb diet -- if you cut out all fat, including even butter on the bread, and have only carbs and vegetables. Vegetables you can eat with anything, because they don't really have any fat in them to store.

Instead of the high carb, low calorie diet, I prefer the other way around: eat a high protein, low carb diet, with all carbs being natural ones from vegetables. No refined carbs and no sugar whatsoever. Because there are no insulin spikes, I can eat things with tons of calories and plenty of fat and not worry about gaining weight. It's good to avoid saturated fats, of course, since they are unhealthy.

When I practiced this way of eating in high school, not only did I feel like I had tons of energy, but I lost weight without even exercising. I'm looking to get back into Somersizing, because it worked for me and now that I'm eating carbs and sugar again, I'm once again gaining weight.


@oasis11 - Thank you for that explanation! I've already thought of low calorie diets as unhealthy, and low carb diets as the way to go. As with anything, either one can be taken too far, though. It's just as unhealthy to eat an absolutely no carbohydrate diet with too much saturated fats as it is to starve yourself on an extremely low calorie diet.

There are a few reasons that I personally believe low carb eating is better than low calorie eating...

First of all, food allergies run in my family. I don't have any outright allergies, but I've noticed that I get an urge to clear my throat constantly for several hours after eating anything containing gluten. That's a food sensitivity -- if I keep eating gluten much, I'll probably develop an actual allergy to it.

Secondly, from personal experience I can tell you that the moment I start eating carbohydrates regularly, even when I cut out most or all sugar from my diet, I start putting on the pounds. Not only that, but after any carbohydrate meal, I feel fuzzy in the head and I can't focus.

It is my belief that some people are carb sensitive, and need to avoid refined carbs as much as possible.


@SurfNTurf- I agree and I wanted to say that a weight loss plan that forces you to eat less 1500 calories is probably one that is going to cause you to lose muscle and a lot of water weight.

This will have a negative impact on your metabolism and cause you to gain weight over time even though you haven’t changed your diet.

This is what happened to Oprah years ago when she publicly announced that she was following a liquid diet. She lost a lot of weight but only maintained her weight for a day and then dramatically gained all of her weight back and then some.

The diet really damaged her metabolism and she had to work hard to repair it.


@Popcorn- I think that if you eat lean protein and limit the carbohydrates and sugar that you intake you could really put together a ketosis diet that offers weight loss at healthy levels. When you cut out sugar and processed foods, you will probably get a headache but it should go away after a few days and then you will probably have a lot of energy.

I think that importance is to eat a variety of healthy foods and exercise that can change your lifestyle for the better. The people that see a weight loss plan as a lifestyle change are more successful than people that want weight loss for very short term goals like they are getting married or going to a reunion.

People that make a lifelong commitment to lose weight realize that progress is all that matters not perfection. Small positive changes make a big difference over the long haul.


Does anyone know if low carbohydrate diets that promise you will go into ketosis is the same as starvation ketosis?

I have been reading a lot about high protein, fat diets and there are people who have seemed to have a lot of success with them. I tried the diet for a week and felt terrible. I was weak and nauseated by the change in diet. I did lose weight, all while consuming a lot of calories, but I didn't feel good about it.

Do you think there is a safe way to bring on ketosis without feeling ill? Or is that part and partial to this technique?


Starvation ketosis is one of the things you rarely hear about when people try extreme dieting and do there best to just not eat. Our body needs a certain amount of carbohydrates. While it may sound great to have your body doing its best to use your fat, it is actually a survival tactic.

For those of you who want to lose a few pounds, the damage done by short-term starvation is not worth it. You should consult your doctor before trying large dietary change. You don't want to end up shocking your system and making yourself gravely ill.

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    • The conversion of fat into ketones occurs in the liver.
      By: kaianni
      The conversion of fat into ketones occurs in the liver.
    • Diabetes can interfere with the liver's metabolic process causing ketosis.
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      Diabetes can interfere with the liver's metabolic process causing ketosis.
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      Alcoholism can cause starvation ketosis.
    • When fatty acids are broken down in the body, ketones are formed.
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