Prevent A Slowing Metabolism: Understanding Metabolic Slowdown And Adaptation

Cliff Wilson
Written By: Cliff Wilson
July 30th, 2012
Updated: June 13th, 2020
Categories: Articles Nutrition
141.8K Reads
How and why does your metabolism slow while losing fat? Bodybuilding coach Cliff Wilson provides 6 tips on how to maximize your fat loss efforts.

Slowing MetabolismI see it ALL…THE…TIME! Metabolic damage and serious metabolic issues are rampant in the sport of bodybuilding. Metabolic damage is essentially a drastic slowing of the metabolism that is caused by excessive calorie restriction, excessive cardio, and stress on the body.

I think I can speak for all good prep coaches out there when I say that there is probably not much that is more frustrating than starting with a new client only to find that they have a completely crashed metabolism. To make matters worse I usually learn that they have been coached to that point by a previous trainer.

The reason this is so frustrating to me as a coach is because before this new client and I can even begin thinking about losing fat, we first must "fix" their metabolism. This is no easy task and can take months or even up to a year. So I am here to officially say, hours of cardio and cutting calories to ultra-low levels is not the way to get lean.

Female competitors are particularly plagued by this issue. Fat loss does not come as easily for the majority of women as it does for many men. As a result many will resort to drastic measures in an effort to get shredded.

Male or female, only the most motivated competitors are affected by this problem. The unmotivated competitor will give up long before things get to this level while those that are truly motivated will push through and do whatever it takes to get lean. The attitude of “whatever it takes” is common in this sport. Anyone that will do “whatever it takes” to win will not rule out starving themselves or doing several hours of cardio per day.

How A Slowing Metabolism Happens

Let me run you though a scenario with which I am sure many people are familiar. Let's say we have a competitor that is prepping for an upcoming bodybuilding show. Our competitor has put on a bit too much fat in the offseason, so being ready on time is going to be difficult. Since time is of the essence our competitor begins with aggressive cuts to his diet.

He was maintaining his body weight with about 3000 calories per day in the offseason, so he begins by cutting to 1600 calories and starts by doing an hour of cardio a day. This really gets things moving as he loses several pounds in the first few weeks. Eventually things begin to slow down though.

After a few more weeks fat loss has pretty much stalled, so our competitor, who is already eating very little, decides to cut out all carbs and lower his fat intake down to 20-30 grams per day. This gets things moving again but not nearly as fast as in the beginning. After another few weeks fat loss stops again. Since he really can't eat much less than he is currently eating, our competitor has no choice but to add another hour of cardio per day.

Fat loss barely crawls along for the next few weeks before it inevitably stops altogether. Our competitor is exhausted, has no energy to train, is eating no carbs, very little fat, and doing 2-3 hours of cardio per day, but the scale does not budge. There is still more fat he needs to lose, but our competitor is out of luck. His metabolism has stalled and it is not going to give up any more fat.

This is exactly the type of situation that leads to a huge metabolic slowdown and makes it nearly impossible to lose any fat. Now that we have identified how this situation occurs the big questions that remain are, why does it happen, and what can you do to prevent it?

Cardio Running

Why A Slowing Metabolism Happens

Let’s clear one thing up right now. It is normal for the metabolism to slow down on any diet or calorie restriction. This is all due to metabolic adaptation. For a successful prep you need to understand how the body adapts to survive. The human body is an amazing adaptive machine that will always strive for homeostasis. Whatever conditions the body is put in, it will strive to survive within that new norm.

If you remember our bodybuilder in the previous example, he was eating 3000 calories a day to maintain his weight but he cut to 1600 to lose fat. As soon as he cuts calories his metabolism will begin to slow. Many people do not realize that the body uses calories just digesting and processing food. This is described as the thermic effect of food. So the simple act of eating less causes less energy output.

Once the body senses that fat loss is occurring it will begin to lower thyroid levels and diminish nervous system output in an effort to stop the weight loss. Once further calorie cuts are made and cardio is increased fat loss will resume again, but the body will further lower thyroid levels and nervous system output. It will also lower testosterone levels and raise cortisol levels, which will eventually lead to muscle loss. Since muscle is metabolically active tissue, meaning it requires calories simply to exist, the metabolism will drop even further.

So why does the body sabotage our effort like this? It is simple…survival. If the body did not make these changes it would be in serious trouble. If our bodybuilder eating 3000 calories a day cut his calories to 2500 per day and his body did not have these adaptive abilities, he would lose weight continually without stopping until he would eventually die. Luckily nobody is starving to death on 2500 calories per day (even though it may feel like it sometimes). So you see,these are normal adaptations that are necessary for survival.

Always remember that as soon as you make a change that will affect calorie intake or expenditure your body will immediately begin taking measures to reach homeostasis.

Metabolic Slowdown As A Cycle

From my experience, metabolism crashing is a cycle. People drive their metabolisms into the ground for their contest prep leading to a seriously slowed metabolism. Someone with a tanked metabolism cannot handle many calories at all. Yet after the show is over, most will tend to binge excessively as the months of restriction have now caught up with them mentally. Their metabolism is not equipped to handle this level of calorie intake and the fat gain is fast and furious. This leads to getting extremely heavy, yet the metabolism will remain depressed.

I have also found that most competitors that have prepped incorrectly to the point of having serious metabolic issues do not get lean enough. As a result many are not particularly pleased with their placing and are eager to get back on stage and redeem themselves. These competitors typically take little to no time off before prepping for another show. So they begin their prep with an already lowered metabolic rate, too much fat lose, and not enough time to lose it. The cycle begins all over again.

How To Prevent A Slowing Metabolism

Luckily there are several ways to prevent these serious metabolic issues from occurring. While the metabolism will slow a bit on any diet it does not and should not have to lead to extreme calorie deprivation and hours of cardio. Not only is this not healthy but in the end it will not get you lean enough. So here are the rules to follow for a better prep.

Tip #1 - Be Patient

Fat loss should not be rushed. You need to allow plenty of time to diet. You should aim to lose no more than 2 lbs. of fat per week and preferably keep a rate of 1-1.5 lbs. lost per week. This will ensure that muscle loss is minimized. Remember that muscle tissue is metabolically active meaning it uses calories just existing. This goes a long way toward keeping a healthy metabolism.

Another part of being patient is learning to make minor changes to the diet rather than massive cuts. Keep in mind that as soon as you make a change, whether it be cutting carbs or increasing cardio, your body will begin adapting to the change. Every change you are able to make to increase fat loss is a tool in your tool bag.

Do not use all of your tools in the first few weeks. If fat loss stalls and you cannot cut calories any lower and are already doing hours of cardio per day there are no more moves to be made. You need to save something up your sleeve for the end of the prep when you will need it.

Tip #2 - Keep The Carbohydrates

There is no denying that if you want to get lean you sometimes have to drop carbs to low levels. This does not mean that you should cut them out altogether though. Carbs increase cellular osmotic pressure (cellular hydration) and therefore cell volume.

When muscle cells are hydrated and have greater volume this sends signals to the body that it is in a fed state. The body, sensing it is in a fed state, then keeps the metabolic rate raised. Obviously if carbs are too high then fat loss cannot occur, but for continued fat loss carbs must remain in the diet.

Tip #3 - Utilize High Carb Days

Carbohydrates are essential to keeping an elevated metabolism and leptin is a primary reason for this. Leptin is a fat burning hormone that is directly related to carbohydrate intake and body fat levels (Romon et al, 1999). Leptin is a fat burning hormone that serves many functions, including the control of energy expenditure.

While we have already noted that to get truly lean carbs will eventually have to be lowered. As carbs get low and body fat levels dwindle the body will inevitably lower leptin levels. This can be combated to an extent by adding in high carb days. A high carb day once every 4-8 days can boost leptin levels since leptin is highly responsive to glucose metabolism.

Adding high carb days will not only boost leptin but it will lead to a more positive hormonal profile in general. Higher carb days can lead to higher levels of the thyroid hormone t3 as well as even keep testosterone levels elevated, which will further fat loss efforts.

Tip #4 - Don’t Cut Fat Too Low

Fatty acids are substrate for cholesterol, meaning that fatty acids must be available to create cholesterol which is eventually converted to testosterone. If fat intake is too low there will not be enough fatty acids available for optimal testosterone production. This will lead to lower testosterone levels. Low testosterone leads to greater muscle loss during prep, meaning a lower metabolic rate.

The body also has a built in adaptive response to chronically low dietary fat intake. When the body senses an extremely low intake of fat it will naturally try to hold on to body fat stores and fats are now at a premium. Taking in moderate amounts of fat will ensure that calories are low enough for fat loss, but the body does not perceive it as starvation.

Tip #5 - Reverse Diet

Reverse dieting is essential to prevent the cycle of metabolic slowdown or stop it if you are already in the situation. Just because the show is over it does not mean that it is time to begin eating anything and everything. After the show is over a proper reverse diet must be employed.

A reverse diet is where you essentially add calories back into your diet slowly much the same way you cut them slowly in order to get lean. This will prevent copious amounts of adipose tissue from collecting within the first month or two after a show.

Even the best contest prep in the world will lead to a significantly slowed metabolism. Similarly, the human metabolism can be raised by systematically, but slowly, adding protein, carbs, and fat. If you already find yourself with a crashed metabolism then a good long reverse diet is the best prescription to help get back on track.

Tip #6 - Don’t Get Too Heavy In The Offseason

Getting too heavy in the offseason is often how metabolic issues get started. I’ve already discussed how metabolic adaptations to excessive measures for fat loss can cause serious metabolic slowdown. Newer research is showing that losing massive amounts of fat will cause dramatic slowing of resting metabolism out of proportion to weight loss, even when fat free mass is maintained. This metabolic adaptation may even persist during weight maintenance (Johannsen et al., 2012). Starting your prep at too high of a weight sets the stage for drastic measures that invite excessive metabolic slowdown.

So while all the other factors are still very important it all begins in the offseason. The days of gaining 60 lbs. in the offseason and trying to lose it all in a single prep are over. Those that are willing to do what it takes even in the offseason will be rewarded on show day.

What It Takes

Doing “what is takes” to win is not a bad thing. The problem is that too few identify what it actually takes to win. When dieting for a show, blind hard work is not the answer. Just because you work as hard as, or harder than someone else does not mean it is more effective. It is much like running a marathon. While a marathon is 26.2 miles some people in bodybuilding would run 35 miles just to say they worked the hardest.

To top it all off most of them would be running in the wrong direction! So they worked harder and still placed last. The point is that blindly working hard for the hell of it won't cut it. Get a plan and THEN bust your ass! Your metabolism will thank you.

Posted on: Fri, 08/24/2018 - 14:12

Thank you. I really respect this article.

Posted on: Thu, 01/18/2018 - 17:08

Cliff's writing is so easy to understand and read! Great article.

John Thomson
Posted on: Tue, 07/08/2014 - 13:24

Good article. Yes fat loss is always slow at 3,500cals per lb. if you are loing WEIGHT fast it's not fat. Contest prep should be about 1lb or thereabouts a week. Cardio is not a fat loss prescription and is only for those who have little nutrition knowledge and burns valuable carbs and may cause catabolism of muscle, certainly in natural bodybuilders. Zig zagging your cals and carb depleteing and loading in balance with your training keeps muscle mass and fat loss.
Diet is the key, never compromise your recovery by trying to burn fat with exercise. Sleep is your fat burning friend. Kind regards John Thomson

Posted on: Sun, 06/16/2013 - 14:46

Really informative article - thanks Cliff.

I'm not a BB but have a very slow metabolism, coupled with hypothyroidism and masses of weight loss (126lb to 91lbs, 5'7" female) Finding information on people having a slow metabolism AND losing lots of weight is impossible online. My autonomic NS is out of control, hypothyroid, hypo-adrenals, and i'm consuming loads of calories, BB formulas aswell as reducing cardio but i've only gained 7lb in 9 months.
It's possibly more of a medical condition, but haven't yet found a doctor who will help, but wondered if you could shed some light from a metabolism angle. It sounds like my body has gone into starvation mode and is stuck in it despite my calorie increases. What else could help me pile on weight?

Posted on: Wed, 03/27/2013 - 04:40

Hi, stumbled across your page. Although I am not nor ever have been in any comps, I have been a yoyo dieter for years and think my metabolism is destroyed from this. Would I still use tip 5 even to I have a drastic amount of weight to try to lose in a healthy way. Thanks in advance,

Posted on: Wed, 03/27/2013 - 04:40

Hi, stumbled across your page. Although I am not nor ever have been in any comps, I have been a yoyo dieter for years and think my metabolism is destroyed from this. Would I still use tip 5 even to I have a drastic amount of weight to try to lose in a healthy way. Thanks in advance,

Rob Marcelletti
Posted on: Sat, 03/16/2013 - 17:32

I've been a national level "natural"competitive bodybuilder for 14 years , I've learned that you must utilize a periodazation program that takes advantage of the post competition glycogen super compensation. This is the only way I have been able to gain almost 70 lbs of muscle mass in 11 years. I'm almost 50 now and maintain 200 lbs at 5' 8" & 12% body fat year round with no anabolics, my high LBM makes my metobolism extremely high and very easy to drop body fat come contest time.

Thasegan Pather
Posted on: Thu, 02/28/2013 - 08:50

within 6 weeks of a combined cardio and resistence workout, i get the common flu pretty bad. The diet changes to reduce carbo and sugar, but no supplements. What am I doing wrong?

Posted on: Sun, 02/24/2013 - 17:02

What about dieting for non professionals, does that formula still apply?

Posted on: Wed, 01/30/2013 - 22:58

Really excellent article. Nice work.

Posted on: Sun, 01/13/2013 - 16:24


I just found this article and it's like a revelation. This describes me to a tee. I know the precise answer probably depends on a lot of factors but say I've been dieting pretty hard for 6 mos, how long would you think one would need to reverse diet before attempting to cut again?

Thanks so much, FANTASTIC article!!!

Posted on: Thu, 09/13/2012 - 08:18

Thank you for enlightening. Quite insightful and written in simple words.

Stephanie Barker
Posted on: Wed, 08/01/2012 - 05:56

Love it Cliff!

Andrew Pardue
Posted on: Tue, 07/31/2012 - 12:47

Great article, always enjoy reading new articles from you!

Posted on: Tue, 07/31/2012 - 03:47

Great article!
How can we fix a metabolism?

Cliff Wilson
Posted on: Fri, 08/03/2012 - 04:41

Hey Andrea,

Glad you liked the article. If you find yourself with an already damaged metabolism then Tip #5 is you answer. A good long reverse diet is the only answer. Slowly adding in food over a long period of time will help get things back on track by returning hormonal balance and CNS output. You will have to put on a bit of fat but it is a small price to pay. The goal is to put on minimal fat but always aiming to eat more. I hope that helps.

Posted on: Fri, 08/03/2012 - 12:11

Thanks Cliff, i have another question for you....
How long should last that period?Do you think that 6 week eating at maintenance level and then making a small deficit by 10-15% (decreasing carbs by 25%) is a good plan?

Posted on: Thu, 03/28/2013 - 06:20

Hi, would I do the same thing if my metabolism has slowed not due to comps, but due to many many years of yoyo dieting, thanks

Kerri Bolen
Posted on: Mon, 07/30/2012 - 19:06

Great article, Cliff!

Posted on: Mon, 07/30/2012 - 17:17

i couldnt agree more with you.. 100% true... this is why a cheat meal is advised every week to let your body know that there is nothing going wrong and it can start burning again.

another way us to do Carb cycling like high carb days every week like u mentioned and low carbs for like 4 or 5 days... and also Fish oilllllllllllll is a must so it burns fats and keep lean muscles and keep ur insulin level normal...

Schae Zarew
Posted on: Sun, 04/14/2013 - 19:09

Not even really a cheat meal as it is basically "binging", simply increasing calories by 200 or so can be classified as a refeed day and will trick the body. Unless cheat meals are counted and arent that dense in calories, most people go way over the top.

sohee lee rever...
Posted on: Wed, 06/24/2015 - 07:52

This is a really inspiring article. I find it highly informative. Am pretty sure lots of people would find great value in this write-up. Keep up the good work

Rob Johnson
Posted on: Sun, 04/02/2017 - 01:52

Great article. Are references available?