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Metabolic Damage
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Metabolic Damage

Metabolic damage is a topic of discussion that has been gaining widespread attention within the fitness industry of late, particularly among the competition community. This is largely due to the efforts of notable industry leaders such as Dr. Layne Norton and others in bringing the subject into the public awareness.

But what exactly is metabolic damage? Why does it occur and how harmful is it really? Does the average person who’s simply trying to lose some weight or get into reasonable shape need to be concerned about it, or is it only an issue for fitness competitors?

In this article I aim to answer all of these questions about metabolic damage and more, in plain and simple terms.

What is Metabolic Damage?

Well, let me start by saying that although the term “metabolic damage” seems to have taken a foothold in popular usage, it’s in fact somewhat misleading. That’s because there’s no actual damage, or harm, caused to your system, but rather simply a reduction in your body’s metabolic rate. A reversible one, at that.

A much more accurate description of this would actually be metabolic adaptation, since it’s nothing more than your body adapting to certain changes in your lifestyle – namely, a reduction in calorie intake and/or an increase in energy expenditure through low intensity cardio exercise.

This adaptation by your body is in fact part of a very important self-preservation mechanism that’s designed to keep you alive and functioning in periods of crisis where you’re not getting adequate food. It’s sometimes referred to as the starvation response.

You may have heard stories, in the news for example, of people stranded in isolated places surviving for long periods of time without food. This is made possible by their body exhibiting a starvation response. In other words, it adapted to the lack of food by slowing down its metabolic rate, therefore reducing its energy expenditure to allow it to survive as long as possible.

That’s great news if you’re ever lost in the jungle, but when you’re simply trying to lose some body fat it can be quite a hindrance, unless you go about it the right way.

What Does Metabolism Mean?

Going back one step for a moment, let’s look at what exactly your metabolism is. The term metabolism simply refers to your body’s process of converting energy (calories) into work, as it runs all of the processes that keep you functioning and alive.

A person whose body has a low metabolic rate, or a slow metabolism, therefore uses fewer calories each day to perform the same functions as a person whose body has a high metabolic rate, or a fast metabolism.

The higher your metabolic rate therefore, the far easier you will find it to lose body fat and vice versa, since body fat is shed through the burning of calories.

How Does Metabolic Damage Occur?

Metabolic damage occurs when you restrict your dietary calorie intake too aggressively, and/or when you perform excessive amounts of low intensity cardio exercise.

When either of these conditions exists, your body adapts by slowing down its metabolic rate to compensate for the reduced energy intake or the increased energy expenditure, as the case may be.

The degree to which this adaptation occurs depends upon the severity of the condition, as well as the genetics and physiology of the individual. In other words, it’s different for everyone.

Once your metabolic rate has slowed to a certain level, you experience a situation known as plateauing, where your fat loss essentially stalls. At that point, the only way to resume the fat-loss is by eating fewer calories still and/or by burning more calories through additional cardio exercise.

This course of action, however, leads to further metabolic adaptation, which leads to yet another plateau, and the cycle continues, until a point is reached at which further fat loss becomes virtually impossible.

The exact mechanism by which your body changes its metabolic rate and acts to conserve energy is very complex – it’s not simply one single process but rather a combination of many processes.  For example:

  • muscle atrophy (wasting) increases,
  • thyroid hormone decreases,
  • energy burned during exercise decreases,
  • the efficiency of energy production within the cells increases,
  • fat oxidation (burning) decreases,
  • energy burned to process the food you eat decreases,
  • energy is extracted from the food you eat more efficiently,
  • the expression of genes that promote fat storage changes,
  • you experience more hunger signals,

and so on.

Metabolic Damage and Fitness Competitors

There are three major reasons why metabolic damage is so prevalent and such an issue among fitness competitors.

Firstly, as part of their contest preparation process, competitors need to “cut down”, or shed body fat, to achieve a stage-ready physique that most often involves very low body-fat percentage levels.

The lower your body drops in fat percentage, the more reluctant it becomes to shed more body fat. In other words, its metabolic adaptation becomes more and more pronounced the leaner it gets, to conserve energy and therefore inhibit any further fat loss.

Secondly, fitness competitors very often compete over one or two seasons each year, meaning that they continually cycle their weight, from very lean during each competition season to anywhere from say 5lb to 20lb over their contest weight during each off-season.

Your body tends to somehow have a medium-term “memory”, for want of a better term, whereby the metabolic adaptations it makes to dieting become more pronounced each time. Each time a competitor diets therefore, it can become a little more difficult to cut body fat.

The more frequent these weight cycles are, the more pronounced the metabolic adaptations are. This is precisely why rapid yo-yo dieting is so destructive to your metabolism. Even dieting for a contest once a year however, will often lead to increasing metabolic adaptations of some degree each time, depending on the individual.

Thirdly, the sad fact is that a large number of trainers who are involved in preparing men and women for competition are either:

  • simply unaware of the power of metabolic damage,
  • are aware of metabolic damage but don’t know how to avoid it,
  • or they are aware of it but choose to use unhealthy and even dangerous “brute-force” methods to get quick and easy (for them, not their clients) results.

These methods typically include starvation (calorie intakes of less than 1,000 calories a day, sometimes as low as 500 calories a day), several hours of low-intensity cardio exercises a day, and the use of dangerous drugs and hormones.

Metabolic Damage and the Average Person

So what if you’re someone who isn’t a fitness competitor and therefore aren’t dieting once or twice a year to low body fat levels, but rather just trying to lose some weight? Do you still need to worry about metabolic damage?

Well, although metabolic damage may not have as pronounced an effect in your case, especially if you’re restricting your calories for the first time in a long period of time, you still need to be aware of its effects.

Because your body tends to adapt to any reduction in calorie intake to some degree, encountering plateaus at one time or another during your fat loss process is not at all uncommon.

By recognizing and understanding the effects of metabolic damage however, you’ll be able to both avoid plateauing as far as possible, and also work through any plateaus if and when they do occur.

How to Avoid Metabolic Damage

Whether you’re a fitness competitor or someone simply trying to lose some body fat and get into shape, there are measures that you can and should take to avoid succumbing to the effects metabolic damage.

Some of the more important ones include:

  1. Go slow. The less body fat you lose each week, the less of an adaptation you’ll encounter. Most people aiming to lose weight should be targeting about 1lb to 2lb of fat loss per week. As your body fat percentage gets lower (competitors take note), your body will be less reluctant to shed fat, so you should only aim for about 100g to 250g of fat loss per week.
  2. Don’t drop your calorie intake suddenly, slowly ramp your intake down over time.
  3. When you encounter a plateau, back off what you’re doing. If you’re in the process of ramping down your calorie intake each week, hold it steady or increase it slightly for a while (up to a few weeks), then resume the steady calorie reduction once more. If you’re at a fixed calorie deficit on the other hand, increase your calorie intake slightly for a while.
  4. Remember that consuming fewer calories doesn’t always equate to more fat loss. When you’re experiencing metabolic adaptation, consuming fewer calories leads to more adaptation, which actually means less fat loss. In this case you need to “re-feed” your body to allow the adaptation to reverse.
  5. Don’t rely solely on low-intensity cardio exercise to burn calories. This form of exercise has been shown to lead to the most adaptation, where your body becomes accustomed to the exercise so that it becomes less and less effective at burning calories. Combine high intensity interval and circuit training into your exercise routine.
  6. Include resistance training in your exercise routine to prevent loss of muscle mass.

What To Do if You’re Affected by Metabolic Damage

As I mentioned earlier, metabolic damage occurs when you restrict your dietary calorie intake too aggressively.

And just as decreasing your calorie intake leads to metabolic damage in the first place, increasing your calorie intake causes a reverse adaptation, or a reversal of the metabolic damage.

The only problem is that in the “damaged” state, where your metabolic rate is extremely low, an increase in calorie intake will very likely lead to instant weight gain. This is precisely why so many fitness competitors experience so-called “rebound” following a competition season, and why so many dieters gain back their lost weight and more once they revert to their original eating habits.

For this reason the process of increasing your calorie intake to repair metabolic damage needs to be carried very slowly and patiently, so that your metabolic rate can be nursed back to health with a minimum of unwanted weight gain.

Depending upon the individual and the severity of the adaptation, this process can take anywhere from several months to up to two years in extreme cases.


The three golden rules that you should always keep in mind then, to help you avoid metabolic damage while losing weight are:

  1. Be patient – always give yourself plenty of time to lose the required body fat.
  2. Always make small, gradual changes to your calorie intake, whether increasing or decreasing it.
  3. Always eat as much as possible while losing the weight you require.


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Fabian Colussi is a women's Bikini and Figure competition coach for natural athletes, certified personal trainer and gym instructor, and women's fitness consultant. He also has a background in martial arts, is an NLP Master Practitioner, and has a certification in Hypnotherapy. Fabian is a co-owner and co-founder of Million Dollar Baby Fitness.

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