What Happens When Your Body Goes Into Starvation Mode?

Starvation mode is a term that is used a lot in the fitness space.

The main idea is that going overboard with restricting your calories and possibly combining that with a lot exercise will put your body in a state where it spends significantly less energy.

Most commonly starvation mode is used to explain a complete halt in weight loss or to instill fear of restricting calorie intake too much.


“Those calories are too low man, you will end up in starvation mode and not lose any weight!”

In this article, I will explain what happens when your body goes into starvation mode, why it doesn’t matter and some other reasons why you simply burn fewer calories when in a calorie deficit.

The calorie deficit is as you might know a requirement for weight loss.

Damaged Metabolism

A damaged metabolism or metabolic damage is another term that covers the same idea but arguably in a little bit different way.

Here the idea is that some dietary choices like dropping calories too low or restricting one macronutrient can damage your metabolism resulting in fewer calories burned than normal.

Metabolism is just the physiological process of producing energy for your body.

I will leave metabolic damage for another time, however, I can briefly say that very extreme circumstances like in the old and famous Minnesota Starvation Experiment from 1945 can perhaps lead to something of the sort.

However, it is completely reversible and not as not dramatic as you might think.

pin me to get out of starvation mode 🙂

“Starvation Mode” – A Physiological Adaptation

The first thing you have to understand is that the body is amazing at adapting to whatever stresses it encounters.

It is a primal function of the body to always adapt often using a guiding principle of remaining the same (homeostasis).

How much energy you need to sustain yourself (Basal Metabolic Rate – BMR) and the energy you spend throughout the day is by no means a static thing.

It changes and adapts according to different variables including the energy contents of the food you are eating.

Basically, if there is a deficit in your energy balance your body seeks to reduce or eliminate the deficit by using less energy.

E.g. becoming more efficient and conservative at using energy.

It is a completely normal and inevitable physiological adaptation and makes perfect sense from the standpoint of self-preservation.

But calling it starvation mode is being overdramatic and the effect is really not that big.

The size and duration of the calorie deficit matter, but there seem to be large individual differences of how significant these adaptations are.

In more technical terms this is often referred to as metabolic adaptation and/or adaptive thermogenesis.

Also, your current body fat percentage plays a role and basically the leaner you get the more your body is “fighting against” your weight loss efforts by affecting your energy expenditure and making you more hungry.

Reducing The Effect

Not a lot is known about how to reduce this effect.

But, some research suggests that doing regular weight training can reduce the metabolic slow-down.

I would also highly recommend doing weight training because it will help you against the risk of muscle loss which is otherwise normal when dieting.

Since the size of the calorie deficit seems to matter it is probably better to have a “moderate” calorie deficit somewhere around 20 – 25 %.

This way you will also avoid feeling miserable and risk not getting sufficient vital nutrients.

Something to take note of which is comforting is the fact that an opposite adaptation occurs when you are overeating.

Within limits of course (regretfully).

Why It Doesn’t Matter That Much

When you are on a fat loss diet things do gradually slow down and get harder both mentally and physically.

While this adaptation is a culprit, the truth is that it is not that big of a deal compared to some other reasons for why you are gradually burning fewer calories as you are successfully losing weight.

The Thermic Effect Of Food

Whenever you eat something your body actually have to spend a decent amount of energy to process it and absorb nutrients and energy from it.

In other words, you have to spend energy to get energy. Pretty cool.

Unless you base your weight loss solely on more physical exercise which is not recommendable, then you have to consume less food.

When you consume less food you will consequently also end up spending less energy on absorption etc.

The thermic effect of food is significant. Research suggests it accounts for about 10 % of your total energy expenditure.

Protein especially has a high thermic effect, and carbs have higher than fat.

Bodyweight And Energy Expenditure

Let’s say that you have been on your fat loss diet for some time and your scale weight has dropped a lot.

Getting rid of excess fat and weighing less is a great achievement, but it also means that you now have to spend less energy moving around.

Basically, you are now moving less weight and any activity you are doing now requires less energy.

The Metabolic Activity Of Your Muscle Mass

Using and maintaining muscle mass requires energy.

Actually, both muscle and organ mass are highly metabolic active and there is a strong correlation between lean body mass and energy expenditure.

So if you are losing muscle mass on your diet you end up spending less energy.

Although maintaining muscle mass should be a big priority for anyone wanting to lose weight a lot of people still lose some.

To eliminate or reduce muscle loss you should do weight training and have a proper diet.

Any resistance training will do, but I think weight training is most efficient.

If you want to learn more about what you should eat to lose fat, then you should get my free nutrition guide and email course.

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Weight Loss Stalling

Before your put all the blame for your sudden weight loss halt on the things I mentioned above, there are a few other things that you should consider.

Using the scale weight as your only metric for measuring weight loss is often inaccurate.

You could be holding a lot of excess water or you could be building muscle.

When your fat cells are emptied they fill up with water which can stay there for a long time before flushed out.

Muscle weighs a lot and especially if you are a beginner then muscle growth can happen quickly.

Finally, you could be eating more than you think.

If you don’t track the calories of the food you are eating it is easy to make wrong estimations especially when you are fighting against yourself and hunger.

Avoiding “Yoyo-Dieting”

Some people regain a lot or all of their weight relatively fast.

But it is not because their metabolism is damaged or because they are in “starvation mode”.

It is simply because they overeat.

It is a common mistake (I did this as well) to go crazy with the food once the diet is finished. There is a lot of food you missed and you are super hungry!

To avoid this I would recommend staying strict with the food you are eating especially in the transition phase.

Know that if you have lost a significant amount of weight you can’t go back to eating the same way as before and maintain your new body composition.

The energy you need to sustain your new body composition is less than when you were fatter.

Starvation Mode Real Or Not?

Some people will say that starvation mode is non-existent and that it is just a myth.

Depending on the definition you can be right to say so as well.

However, there is some truth to it so I think it is better to just say that starvation mode is putting it very dramatically and probably misleading.

It is really just a normal adaptation that occurs but it is not something you “turn on or off”.

Besides, there are other factors that also explain why you are burning fewer calories while dieting.

While all this does make weight loss more complicated it definitely does not make it impossible for you to lose weight.



My name is Marcus, I am a lawyer (LL.M.) and the founder of this website. Besides sometimes doing lawyer stuff, I like to write about fitness and health and share what I have found “works” for people like YOU. If you want to know more about me and my vision for this website then you can click here.

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