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“Metabolic Damage” and “Starvation Mode,” Debunked by Science

“Metabolic Damage” and “Starvation Mode,” Debunked by Science

If you want to know what science really says about “starvation mode” and “metabolic damage,” then you need to read this article.

Key Takeaways

  1. “Metabolic damage” isn’t real, has never stopped someone from losing weight, and doesn’t need to be “fixed” with complex and meticulous diet voodoo.
  2. “Starvation mode” is sort of real, but isn’t nearly as dramatic as many people think.
  3. There are three reasons why you can stop losing weight “for no good reason”: You’re retaining water, you’re gaining muscle, or you’re eating too much (and, most often, more than you think).

If you’re reading this article, there’s a good chance you’re either experiencing or have experienced the following scenario:

You’re dieting to lose weight and are doing everything right. You’re…

And at first, everything more or less went as planned. Your weight and waist went down and muscle definition went up like clockwork.

And then, the gears inexplicably ground to a halt.

For no apparent reason, the scale stopped moving and your reflection in the mirror stopped changing. You understand energy balance and so, determined to get the ball rolling again, you further cut your calories and increased your cardio.

It worked, of course…to a point. And then you got stuck again, and this time you felt even more haggard than before.

What to do? Is this as far as your body will go? Have you reached its set point”? Is a lower body fat percentage just not in the cards for you?

And then you hear about “starvation mode” and “metabolic damage.”

You find stories about people, typically women, who say they aren’t losing weight with extremely low-calorie dieting and hours of exercise every week, and the culprit is (supposedly) metabolic abnormalities caused by calorie restriction.

Essentially, the story goes like this:

Dieting dramatically and incrementally decreases your basal metabolic rate, which eventually halts fat loss, and which requires a lengthy and involved “recovery” protocol to fix the “damage” should you ever want a healthy metabolism again.

Hence, the term “metabolic damage.”

When your body is experiencing the complex set of physiological adaptations that apparently cause metabolic damage, it’s said to be in “starvation mode.” This apparently kicks in the first day of your diet and gets progressively worse and worse as time goes on.

How true are these claims, though? Well, the short story is this:

  • “Metabolic damage” isn’t real, has never stopped someone from losing weight, and doesn’t need to be “fixed” with complex and meticulous diet voodoo.
  • “Starvation mode” is sort of real, but isn’t nearly as dramatic as many people think.

And in this article, you’ll learn why.

Furthermore, you’ll also learn the real reasons why weight loss stalls and what you can do to easily break through weight loss plateaus.

Let’s dig in.

What Is “Metabolic Damage”?

metabolic damage

According to most theories, “metabolic damage” refers to a condition where various physiological systems have been disrupted and, as a result, your metabolism burns less energy than it should.

In other words, it’s a hypothetical state wherein you burn far fewer calories than you should based on your body weight and activity levels. Furthermore, once you’ve “damaged” your metabolism, it apparently remains hamstrung even when you’ve finished dieting and want to just maintain a steady body weight.

It’s called “metabolic damage” because the theory is your metabolism is quite literally “broken” to one degree or another and requires “fixing.”

(And in case you’re not familiar with the term, your body’s metabolism is the collection of physical and chemical processes that it uses to produce, maintain, and destroy material substances, and to make energy available.)

The causes of metabolic damage are allegedly remaining in a calorie deficit for too long and/or starvation dieting, and doing too much cardio is often fingered as well.

Therefore, when you stop losing weight for no good reason or struggle to prevent weight gain after a period of dieting, some people will claim that you probably have metabolic damage that needs repairing.

The evidence to support all of this is almost always stories. Stories of people failing to lose weight on a measly few hundred calories per day, and even worse, stories of people gaining weight on very low-calorie diets and intense exercise routines.

And so people everywhere have become convinced that dieting has screwed up their bodies–maybe even irreversibly–and that their only hope for returning to normalcy is special dietary measures.

Use this workout and flexible dieting program to lose up to 10 pounds of fat and build muscle in just 30 days…without starving yourself or living in the gym.

How Are You Supposed to Fix Metabolic Damage?

The most typical protocol for fixing metabolic damage is simple: you’re supposed to increase your daily calorie intake by small amounts every week, usually 50 to 100 calories, until you’ve reached your predicted daily energy expenditure.

In some cases, very precise instructions are given regarding macronutrient breakdowns as well.

The rationale for this approach is that by slowly eating more calories (instead of drastically increasing intake, which is what many people do after dieting), you allow your “injured” metabolism to “keep up” and process the food efficiently, resulting in a gradual increase in metabolic rate without unwanted fat gain.

This is generally referred to as “reverse dieting,” and while it actually is a good idea to gradually increase food intake after a prolonged period of calorie restriction, you don’t need to do it for the reasons commonly claimed (more on this soon).

What Is “Starvation Mode”?

The idea behind “starvation mode” is similar to metabolic damage.

It goes like this: If you’re too aggressive with your caloric restriction, your metabolism will slow to a crawl, making it more or less impossible to continue losing weight without eating less than your average runway model.

According to many fitness gurus, if you remain in starvation mode for too long, then the next phase of punishment will begin: muscle loss and fat gain.

The only way to avoid all of this, we’re told, is losing weight slowly through a small (10 to 15%) calorie deficit. If we get greedy, they say, we’ll pay for it later.

The way most people describe it, metabolic damage and starvation mode work together to stymie your progress in a process that looks like this:

  1. You eat too little and lose weight too fast.
  2. You plunge your body into starvation mode, and weight loss stops.
  3. You eat even less and move even more, which supercharges the response and causes metabolic damage.
  4. The longer you remain in this state, the less and less weight you’ll lose regardless of what you do, and the more and more damage you’ll accrue that will require fixing.

Well, as you’ll soon see, there’s a shade of truth here, but like many of the things that “everybody knows” in the fitness space, it’s more wrong than right.

Does Weight Loss Actually “Damage” Your Metabolism?

how to reverse metabolic damage


*drops mic*

*shuffles around awkwardly, picks mic back up*

Okay, I’ll explain.

To understand the real science of fat loss, you must start with the principles of energy balance and how your energy intake and expenditure alone dictates weight gain and loss.

Once you understand that, you realize that meaningful weight loss requires that you eat fewer calories (less energy) than you burn for an extended period of time.

For most people, the learning stops here. They wanted the “one weird trick” that would melt away belly fat and love handles, and they got it: eat less and move more.

What they don’t know, however, can come back and haunt them because restricting your calories does more than just reduce your total fat mass–it also affects your metabolism in various ways that make getting leaner increasingly difficult as time goes on.

In short, when you restrict your calories to lose fat, your body sets out to decrease energy expenditure and increase intake. That is, it wants to erase the energy deficit to balance intake with output and thereby halt fat loss.

The reality is losing fat requires that you force your body to do something it doesn’t want to do (mild and prolonged starvation), and in the spirit of self-preservation, it has “defense mechanisms” it employs to fight back.

Let’s look at the major ones.

Your basal metabolic rate slows down.

Basal means “forming a base; fundamental,” and your basal metabolic rate is the amount of energy your body burns while at rest. The biggest energy hogs in your body are your organs and muscles (these are the prime determinants of your basal metabolic rate).

Now, when you place your body in a calorie deficit, hormonal adaptations occur that cause your body to burn less energy while at rest.

The major hormones involved in these adaptations include leptin, ghrelin, thyroid hormones, and testosterone, which are all unfavorably affected by calorie restriction and weight loss.

The “thermic effect of food” decreases.

The thermic effect of food, or TEF, is the amount of energy required to eat, digest, absorb, and store food.

Research shows that TEF accounts for about 10% of total daily energy expenditure, with amounts varying based on the macronutrient composition of the diet.

While restricting calories doesn’t appear to directly reduce TEF, the reduction in overall food intake naturally results in a reduction of total energy expenditure.

You burn less energy through “spontaneous” physical activity.

Every day you engage in varying amounts of spontaneous activity like walking around while on the phone, hopping to the bathroom, drumming your fingers when you read, or bobbing your legs when you think.

The energy burned by these activities is known as non-exercise activity thermogenesis, or NEAT, and it plays a much larger role in total daily energy expenditure than most people realize.

Research shows that NEAT can vary by up to 2,000 calories per day among individuals, and the same research indicates that people could burn an additional 350 calories per day by taking simple actions to increase general activity levels, like taking the stairs when possible, walking relatively short distances instead of driving, doing chores instead of watching TV, etc.

Now, when you’re in a calorie deficit, your body naturally decreases its spontaneous activity levels, thereby (often significantly) reducing its average daily energy expenditure.

Furthermore, research shows that this adaptation can remain for quite some time after regular eating has resumed (which is one of the reasons why weight gain after dieting is so common).

You burn less energy during exercise.

As you reduce your body weight, you also reduce the amount of energy expended during exercise (it costs more energy to move a heavier body).

There’s more to this than meets the eye, however, because studies have shown that even when body weight is artificially increased during weight loss, energy expenditure during exercise remains lower than normal.

Putting It All Together

As you can see, your total daily energy expenditure is a moving target and one of the challenges of dieting is adapting your exercise routine and meal plan as needed to ensure you remain in a large enough energy deficit to continue losing weight.

These changes in your basal metabolic rate, NEAT, TEF, and so forth are collectively known as “adaptive thermogenesis,” and they constitute your body’s primary weight loss “countermeasures.”

They can be very effective, too. If you don’t know how to deal with them properly, they can significantly slow your rate of weight loss or even stop it altogether.

What they can’t do, however, is “break” your metabolism, even when you heavily restrict your calories, eat too little protein, and do little or no strength training.

You can expect a larger reduction in your basal metabolic rate if you do these things, but the effects are far smaller than many people would have you believe.

Several studies have shown that the metabolic decline associated with dieting, including long periods of very low-calorie dieting, ranges from less than 5 to about 15%.

Furthermore, it took about a 10% reduction in body weight to produce the larger, double-digit drops, and most of the research on the matter was conducted with people who made every mistake in the book–they ate too few calories and too little protein and did no resistance training.

We also know that while these effects can persist long after weight loss has stopped, they can also be easily reversed by raising your calories, lifting weights, and eating a high protein diet.

Now, what happens when you do things correctly, you’re wondering? When you use a moderately aggressive but not reckless calorie deficit, eat around 1 gram of protein per pound of body weight per day, and do a few hours of heavy resistance training every week?

Well, studies show that this approach to fat loss can actually increase your metabolic rate and muscle mass.

Thus, metabolic “damage” is a misnomer. The more accurate term is metabolic adaptation, which can work for or against you, depending on your goals and actions.

Is “Starvation Mode” Real?

No, not in the strict sense of how most people understand the term.

As you now know, your body responds to calorie restriction with crosscurrents meant to stall weight loss (adaptive thermogenesis), but there is no “mode” it enters or physiological switch that flips that makes any further weight loss impossible.

The best example of all of this that I know of is one of the most extreme studies on human metabolism ever conducted: The Minnesota Starvation Experiment.

This experiment started in 1944 as the end of World War 2 was approaching, and its purpose was to discover the healthiest way to help the millions of starving people in Europe return to a normal body weight.

As you can guess, this study involved starving people. And by “starving,” I truly mean starving.

Scientists took 36 volunteers (they had the choice of shipping off to the front lines or doing this, and they chose this) and, to replicate the conditions of your average POW camp, had them do several hours of manual labor every day and march 22 miles per week on a diet that provided about 50% of their average daily energy expenditure. For six freaking months.

As you can imagine, things got pretty grim. By the end of the study, the men looked like this…

metabolic damage study

…and some had almost starved to death, and one even cut off several of his fingers to finish early.

What about their metabolisms, though? Were they as devastated as proponents of metabolic damage and starvation mode would predict?


After losing about 25% of their body weight on average, their basal metabolic rates were, on average, about 20% lower than scientists predicted based on their body weights.

In other words, their metabolisms were “under-performing” by about 20% on average after enduring six months of the most extreme weight loss regimen you could ever devise.

Then, in the next phase of the study, subjects were put on a “recovery diet” to allow them to regain most of the weight they lost, and after 12 weeks of this, their metabolic rates were assessed again.

This time, average metabolic rates were only about 10% lower than where they should have been, and in some cases, everything was back to normal, as if nothing had ever happened.

Not great news, of course, but not too bad considering what they had put their bodies through.

For example, if you started your weight loss journey with a BMR of about 1,800 calories per day, played Auschwitz for six months, and then regained the weight lost, you could expect a BMR of about 1,600 calories per day. Again, not ideal, but not enough to make you incapable of losing weight again.

It’s also worth noting that, according to a new study (largely compiled by a member of my scientific advisory board, Menno Henselmans), when you look at the data over the long-term (instead of just the first 12 weeks of recovery), there’s no evidence any of the people in the experiment suffered from lingering “metabolic damage.”

That is, everything went back to normal, but in some people, it just took longer than 12 weeks.

This groundbreaking experiment provided another nail to drive into the coffin of starvation mode, as well:

Every participant continued to lose weight up until the very end. The rate of weight loss slowed down, of course (for the reasons given earlier), but never came to a complete standstill.

It’s safe to assume, then, that if people can eat about 1,500 calories per day and do many hours of moderately intense exercise every week and still lose weight steadily…for six months…then we have nothing to worry about.

So, if metabolic damage and starvation mode can’t cause you to stop losing weight, what can?

The Real Reasons You Stop Losing Weight

There are three reasons why you can stop losing weight “for no good reason”:

  1. You’re retaining water.
  2. You’re gaining muscle.
  3. You’re eating too much (and, most often, more than you think).

That’s it.

Trust me.

Your metabolism isn’t a unique snowflake. Your body runs on the same type of machinery as mine and everyone else’s. You just have to learn how yours is tuned and make sure you’re not making some weight loss common mistakes.

Check out this article to learn more:

The Definitive Guide to Why You’re Not Losing Weight

The Bottom Line on Metabolic Damage and Starvation Mode

metabolic damage repair

Metabolic damage and starvation mode are mostly bogeymen.

Your metabolism might decline as you lose weight (but might not), but if you know what you’re doing, the effects will be negligible and quickly reversed with a short period of “reverse dieting” once you’ve reached your target body fat percentage.

Even if you’ve already done everything wrong to drop pounds–starved yourself, ate very little protein, did way too much cardio–you still don’t have anything to worry about. Even the most extreme circumstances can only produce a small decline in metabolic rate, and it disappears naturally with normal eating.

Lastly, if you’re currently stuck in a weight loss rut or have been in the past and want to know why, it almost always comes down to one or more of three things:

  1. Water retention.
  2. Muscle gain.
  3. Overeateing.

And to learn why (and what to do about it), read this article.

If you liked this article, please share it on Facebook, Twitter, or wherever you like to hang out online! 🙂

What’s your take on metabolic damage? Have anything else to share? Let me know in the comments below!

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I'm Mike and I'm the creator of Muscle for Life and Legion Athletics, and I believe that EVERYONE can achieve the body of their dreams.

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  • Karen Tozzi

    What are your thoughts on the results of the Biggest Loser contestants? in some cases, I seem to recall they said some people’s BMR was 800 calories less than the average person of their body weight/etc. and this is years after the weight loss and regain [in some cases].

  • less-a-moron

    Played Auschwitz sure gets the point across. Yet someone as talented and knowledgeable as you might have chosen a better collocation.

  • Artar1

    Hi, Mike, thanks for another great article.

    I read your book, “Bigger, Leaner, Stronger,” and followed many of your recommendations regarding protein intake, weight lifting, supplements (especially creatine), and dieting in order to lose weight.

    Specifically, I cut my food allowance by only a modest four to five hundred calories per day while lifting weights twice a week, using a complete body workout each session, and a higher rep count than what you suggested in your book. I also did three hours of moderate-intensity cardio per week as well.

    From experience, I knew that any dieting would cause a metabolic slowdown of about twenty percent. To compensate, I increased my non-exercise activity dramatically by performing five to eight hours of manual labor per day.

    I dropped weight quickly, sometimes two to three pounds a week.

    After seven months of dieting, I’ve lost thirty-seven pounds while gaining some muscle mass. I’ve gone from about thirty percent body fat, at 183 pounds, down to about ten percent, at 145 pounds. In no way do I look like the men pictured in your article.

    Yes, my weight loss has slowed to a crawl, but that’s to be expected. Going forward, if I only lose one or two pounds per month, that will be great. I’m in no hurry now.

    Thanks for all your help.

    • Artar1

      That’s 38 pounds and not 37.

    • Wow, congrats on your success! That’s great to hear!

      LMK if you have any “Before” pictures and we can get you up on the site as a Success Story! Shoot me an email 🙂

  • cmacri

    Thanks for the explanation of NEAT. Now that I’m aware of it (and I think I did know on a subconscious level), on those days when afternoon energy seems to be flagging, I need to get outside and do some gardening or activities with the kids. Good for the body and the mind (and the garden and the kids).

  • Sandra Marr

    Your program worked for me a few years ago, then it stopped working. I think I had an issue way before I started your program (which I think is excellent). I went from losing weight at 1300 kcal to having to eat less than 1000 and gaining at 1400+ which is not sustainable. Some weeks I would gain at an average of 1300. It has taken me ages to find out why. My Doctor said my Thyroid was fine, but eventually I had a full Thyroid Medichecks blood test done, found my Reverse T3 was out of line. There are some doctors in the USA (Dr Holtorf, Haylie Pomroy) who explain how this effects weight gain. My Vit D was low, as was iron, selenium, B12. It is more common than you think. Through supplementation I am having some slight improvement, although it will take months to heal this way as doctors here not great at prescribing T3.

    • Sorry to hear about that Sandra. If you do have some sort of metabolic or hormonal disorder, that could have an effect. Hopefully you can get it remedied and get back on track soon.

      And I’m glad you liked the program, too! Let me know if you ever have any questions about it.

  • Stephen Desjardins

    After finishing reading BLS on July 2nd this year, I bought a Fitbit and started jogging every morning for 45 minutes and adjusting my diet to a 25% deficit. I began at 234 lbs with 31% BF. Today I am 173 lbs at 16.5% BF. All this just jogging for an hour a day – wait until I start weight training… 😉 Your writing makes a lot of sense to me and I love your healthy skepticism, and evidence based methodology. Thank you for the elaboration and explanation made in this article on ‘Starvation Mode’ and ‘Metabolic Damage’. Your article helped clarify some concerns I’ve had over the last four months. My deficit has been… challenging, but I would not call it damging or abusive (though sometimes I do push the envelope). It works well for me and I’m fascinated by the minor adjustments I can make to my daily macro intake, and in turn how that translates to my weigh scale the next morning. Every day is a fascinating experiment. I’m beginning to manipulate my results subtley so that I can now maintain my lean mass while simultaneously decreasing my fat mass – tricky sometimes, but doable. In time I will consider a gym membership (when I can afford it). Thanks for sharing your knowledge and experience, Mike; your words gave me the “Aha” moment I needed earlier this year to realize where I was going wrong in the past, and how I could methodically correct my approach and understanding with the right tools. Much obliged.

    • That’s awesome Stephen! Congrats on the fat loss, and keep up the good work!

      Let me know if you ever need any help 🙂

  • Excellent article Mike! You very clearly and accurately wrote; “when you restrict calories, your body sets out to decrease energy expenditure and increase intake.” This is why losing weight long-term is such a struggle and it has nothing to do with having a “set-weight” as many experts want us to believe.
    Also on reverse dieting, I never understood the purpose of slowly increasing calories back up balance. Energy homeostasis is acutely responsive to daily changes so I’ve found that a cheat day is all I need to keep the key hormones where I want them to be. It’s how I’ve maintained 130 pounds of weight loss for 13 years now.

    • I’m glad you liked the article! Slowly increasing your calories back up is a good way to avoid “letting loose” once you reach your goal on a cut and packing on the fat by no longer paying attention to your intake. Your metabolism does take a bit of time to ramp back up, as well.

      I think there is good evidence for a “set point,” but it’s not set in stone as some say. You can definitely change it. Check this out:


      Regardless, great job on your weight loss and maintaining it for so long. Keep it up!

  • Steve Kirsch

    The study on the Biggest Loser contestants says you can permanently damage your metabolism. “Six years later, calorie burning had slowed further to 1,900 per day, as reported in the journal Obesity.” So the never recovered. How do you explain that? see http://uk.reuters.com/article/us-health-biggestloser/six-years-after-the-biggest-loser-metabolism-is-slower-but-weight-is-back-up-idUKKCN0Y12E9

    • When a study’s findings are at odds with the weight of the evidence on the matter, that’s an indication that something might be awry. In this case, I’d need to read the paper to assess the methodology and findings.

      • Steve Kirsch

        Mike, They averaged 328 lbs at the start, so their BMR calculates (assuming they are 5’7″ male) out at 2620 (which is close to the 2607 measured). They ended at 290. Using the same calculator, they should be burning 2,383 which would be “normal” for their new weight six years later, but instead were burning only 1,900. So they are 483 calories per day “slower” than they should be for a 290 lb weight. I used the calculator at http://www.bmi-calculator.net/bmr-calculator/, but other calculators will yield similar results. This is why the article concluded “Their metabolisms didn’t speed up again when they regained the weight.”

        • Hey Steve, in that particular case, there didn’t seem to be as much of a rebound on average. That said, when you compare it to the vast majority of the evidence, that doesn’t seem to be the case. Something else to keep in mind is that weight regain wasn’t correlated with the degree of metabolic adaptation, so it’s not likely that was the cause. Here’s a pretty good article that goes over some of the best research on the topic: http://carbsanity.blogspot.com/2016/11/is-metabolic-adaptation-real-study-1-of.html

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