Metabolic adaptation explained

Metabolic adaptation explained

Online calculators don’t work – they just provide a starting point from which to work from.

So you’ve gone to an online calculator, plugged your all your relevant information, out pops a couple of sets of macros for your rest and training days and you proceed happily on your diet. Then, some weeks later you stop seeing any changes and appear to have stalled. Why could this be the case?

Well, there are multiple reasons. Now, before we get into them I don’t want to come across as critical of the people who have spent great time and effort to create these calculators to help people. They are good tools to get people going but they are not going to get you all the way. The problem comes when people start thinking that such calculators can predict a diet’s progress accurately. – It says you should be losing 1lb of fat per week because you have calculated a perfect x000 kCal deficit, and so when that doesn’t happen people start to freak out. – How can it be? Did I not calculate accurately?

This is what we will get into in this article.

Assumptions we’re making:
  • You have stalled and need to make a change. So that you know how to identify this situation you need to have read the two posts on tracking, “How to Track your Progress When Dieting,” and “Patience, a Key Tool for Diet Success.” Please. .
  • There is no muscle growth happening while being in a deficit. – Lean body-mass remains constant. (Yes, growth while in a deficit can happen in a deficit under certain circumstances but that’s out of the scope of this article.)
 

1. You Might Not Be in A Calorie Deficit Despite Dropping Weight Initially

This change is due to water weight and it happens for a couple of reasons.

Firstly, because overall carb intake for the week usually goes down due to the lower carb intake on rest days. As carbs suck in 3-4x their weight in water it’s easy to see how big this can be. (and also why you get the scale weight discrepancy between your training and rest days.)

Secondly, and this is less obvious, is the decreased salt intake that occurs when many people decide to go into “cutting mode” and they naturally tend to eat “cleaner foods”. (JCDeen has a great video which sums up why I think the clean eating thing is a bit of a misnomer, but doesn’t change the fact that people have a tendency to eat less-salty, perceived healthier foods when they start their diets.) This causes an initial drop, which rights itself to previous levels in about a week (see FAQ).

I’d say that putting these two factors together you pretty much have the biggest reason that many non-experienced dieters have for failing in the initial stages of their diet. Either the inflated expectations that these weight changes bring lead to subsequent disappointment with progress, or the fear of dropping weight too quick leads people to prematurely change their calorie intake upwards, removing what was a functional calorie deficit.

2. Our Energy Needs Change As We Diet

The Lighter We Get the Fewer Calories We Burn

There are three reasons for this: The energy required to be you is less, so your base metabolic rate (BMR) drops. You’re eating less food, so the calories required to consume that food (TEF) are fewer. And  because you are lighter your exercise program (TEE) burns fewer calories. BMR – Base Metabolic Rate drops TEF – Thermic Effect of Food drops TEE – Thermic Effect of Exercise drops Because of these changes a single calculation made initially will not continue to work in the vast majority of cases.

NEAT Variance

This is your spontaneous physical activity, known as NEAT in geek-speak (Non-Exercise Activity Thermogenesis). We all feel more lethargic on diets right? Fidgeting, moving around, propensity to take stairs vs elevator etc., decreases. The problem with NEAT (and why I have given it a separate sub-heading) is that there are vast individual variances. Some people seem to respond minimally in this regard, some a great deal. (In one study, when subjects were put on a diet 1000kCal above calculated maintenance, the range of increase in NEAT was from -98 to +692 kcal/day.) It’s not unreasonable to assume that people are affected differently when considering the opposite: a deficit. No calculation can take into account these individual NEAT differences.

Metabolic Adaptation

This is the adaptive component of your BMR that is not predicted by weight loss. Basically it is caused by hormonal changes that happen when your body senses a calorie deficit, and so starts doing what it can to decrease your daily energy needs to stop you starving to death in certain survival situations. Modern dieting clearly isn’t a survival situation, but unfortunately our bodies can’t tell the difference between prolonged calorie restriction and starvation, so it’s something we have to deal with. This adaptive component is very real, but smaller than many people think. The largest decrease in BMR due to this adaptive component observed was in that Minnesota Semi-Starvation study and was measured to be about 15%, once the change in total daily energy expenditure, (TDEE) due to weight loss was taken into account.

3. Sub-optimal Macro-Ratio Setting

Referring here to the three macronutrients: protein, carbs and fats.

Fatter folks tend to do better on more fats relative to carbs; leaner folks can get away with more carbs. On top of this, some folks simply seem to do better with relatively more of one than the other. This is exactly why I’m not a fan of online calculators and prefer people to put a little thought into their macros. Which is why I wrote my own guide on how to calculate them.

Now I should be clear, suboptimal macro setting can in the long-term is not going to affect a person’s fat loss efforts (assuming adequate protein intake and a resistance training program). It will still be a calorie deficit after all. However I have definitely seen less stalls, less hunger, and improvements in mood and performance when details are catered to the individual. These side-effects affect long-term compliance and ultimately then, results. I’ll touch more on this in the next post but it’s often a case of try it and see.


Summary

While we can predict somewhat the decreases in energy needs (TDEE) that happen as we get smaller, we can’t predict spontaneous physical activity (NEAT) changes, or metabolic slow-down (without getting thermometers out). So the only practical way to proceed with your diet is to adjust things relative to your current intake – a fresh macro calculation is unlikely to work. Are all macro calculations initially a guess then? Well yes, to an extent I would say so, but we all need a place to start. From there it’s essential to make adjustments based on your tracking data as you progress. So how should one adjust as they go? That’s for the next post, “How to Manipulate your Macros”

Addendum: What about ‘Metabolic Damage’ then?

People are quick to latch onto something to explain their lack of progress. This happens in all areas but especially dieting, where people can become neurotic. – Look at the boom in the supposed food intolerances that we have had in the last 20 years (just check out how many more special meals are being passed around the aircraft next time you are on a long-haul flight). Assuming the worst for ourselves, as we all like to think of ourselves as unique and special, is why I think the idea of Metabolic Damage as a concept has received a lot of attention. Exaggerate a problem, call it a scary name and people will flock to it. And while I have no doubt there are many well-meaning bloggers out there wanting to warn people of the pitfalls (post-diet rebounds, etc.) of setting their calorie intake too low for too long, there are an equal number trying to take advantage of people’s fears.

So what is the truth behind Metabolic Damage? – It’s just your body’s adaptation to dieting.

The popularity of the concept comes in part from people thinking that a single calculation at the start of a diet can predict progress through to the desired result. Then when it doesn’t, they post on a forum with their macro numbers, and voracious fitness reader number 1 does a calculation and concludes that the person has metabolic damage (because that’s what they just read about), to then be backed up by well-meaning forum bunnies 2-9.

As you now know, they are likely underestimating, or not taking into account:

  • Changes in TDEE due to weight loss
  • NEAT variance
  • Individual macro setting

Remember that starvation study? There was a 40% drop in the TDEE of those poor, emaciated fellas by the end of it, just 15% due to metabolic slowdown.

Now, add to this the tendency for 1. Under-reporting of calorie intake, 2. Binges that tend to be forgotten (more under-reporting) and 3. Water-weight games (retention and sudden whooshes – especially common in women, and during periods of high stress), and it’s easy to see how this issue has been blown up. Especially as there will be people with legitimate hormonal issues (that they don’t know about) jumping in and fueling the fire.

Now, I was going to write an entire post on the subject of metabolic adaptation but Lyle McDonald completely nailed it in an issue of the AARR which has just been published online for free, ‘Another look at metabolic damage‘. If you’ve still got questions then ask away there. – Lyle knows way more than I.

Practical tips on adjusting macros after long periods of dieting or low-carbing in the next post.

*******

Thanks for reading.

Browse the other diet adjustment guides using the menu at the top, or get access to my full book on the topic of how I adjust the diets of my clients to take them to shreds and how you can do that too, here.

Questions welcomed in the comments as always. – Andy. 

About the Author

Andy Morgan

I'm an online nutritional coach and trainer. After seeing one too many people get ripped off by supplement and training industry lies I decided to try and do something about it. The site you see here is the result of a lot of Starbucks-fuelled, two-fingered typing. It's had a lot of love poured into it, and I hope you find the guides to the diet and training methods I use on this site useful. When I'm not helping clients you'll likely find me crashing down a mountain on a snowboard, riding a motorbike, or staring at watches I can't afford.

129 Comments on “Why You Need To Make Adjustments as You Diet”

  1. Andy,

    This article was really informative and your website has been absolutely amazing.

    It’s helped me so much and I’ve been making some really good progress on my fat loss journey because of it.

    Thank you.

    Sincerely,

    Mahendra

  2. Mr. Morgan,

    I have been trying to do my due diligence before asking this question, but I cannot find a reference in the material provided.

    Why do you choose not to train people who do not eat meat?

    I am not asking to be critical, I am merely curious if you feel a vegan or vegetarian diet would be a limiting factor and why.

    1. Hi Josh, thanks for the question. Please call me Andy, Mr. Morgan is my dad.

      Why do you choose not to train people who do not eat meat?
      First and foremost, it’s because these people tend to be a pain in the arse personality wise. As a second but still important consideration, it’s because the way I work (letting clients choose their own foods within a rule framework for meeting macro requirements, not monitoring specific foods) could be insufficient when it comes to ensuring that certain types of vegetarian diet aren’t deficient in their protein requirements (in terms of protein completeness). Such things should be handled by a Registered Dietician.

      I am merely curious if you feel a vegan or vegetarian diet would be a limiting factor and why.
      If protein requirements are met with a varied diet, then it (protein completeness) won’t be an issue and the diet shouldn’t be a limiting factor. That’s not going to be possible with a vegan diet to my knowledge (which admittedly is limited as I lack interest due to not having any skin in the game so to speak).

  3. Hi Andy. I know you recommend slowing the rate of fat loss as clients get leaner–but are there specific How To’s for this process? That is, if a client is about to cross the threshold into single digit BF% and has been losing 1-1.5 lbs per week at X calories, would you suggest bumping calories to X + 200 or something of the like in order to slow weight loss down a bit?

    Thank you sir,
    -Ian

  4. Hello Andy,

    I just read your E-Book ‘The Last Shred’ and was curious why you do not use any ‘ReFeed’ Days on your diets as described in the Eric Helms nutrition book.

    Thanks

    -Andre

  5. Hi Andy,

    I would like to get your thoughts on the following idea:

    Is it possible to be too low on a calorie-deficit (from lack of eating and not purposefully through dieting) and then embark on a cutting program (training/calorie deficit) where the calculated calorie deficit is higher than the intake the body was used to having before training?

    I’m thinking this is may be my situation but I’m not entirely sure since I don’t keep track of calories/macros when I’ve fallen “off the wagon”. However, I feels as if I used to eat much less calories during those break times than when I started training. Mainly due to not making meals a priority. Several times I have started a program, gained weight despite crossing all my T’s and dotting the I’s – then stopped

    I’ve wondered if the sudden increase in calories on a new program, even though I’m in a deficit, could be causing that weight gain or no movement at all?

    I don’t really see anyone talking about this so wondered if you had a take on the matter. Thanks, Jon

    1. First and foremost, you need to start tracking your intake, cause unless you do you’ll be forever stuck second guessing yourself.

      Here’s what generally happens:
      1. Someone could have been dieting without counting (thus lowering their metabolism a little). In the majority of cases people successfully diet (for a time) without counting by lowering carb intake, which lowers their water and muscle glycogen balance in the body considerably. This is often confused with fat loss.
      2. Weight loss stalls and they decide to start counting, which inevitably involves a calorie intake calculation.
      3. The calorie calculation will not take into account for the slightly lower metabolism, so it will be slightly too high.
      4. Furthermore, calorie requirements may be set a little higher than they should if they used a calculation technique such as the Katch-McArdle formula, because people underestimate how much body fat they carry.
      5. If people calculate their macros also, they’ll be reintroducing carbs into their diets, which will bring about an increase in water balance and glycogen balance. People confuse this with fat gain.

      The sum of it is that people often set their calorie intake a little high (minor issue which can be corrected after tracking for a few weeks with an adjustment), but they get confused/panic when they gain weight initially, not realizing that it’s water. They quit, thinking they have screwed up, or they simply don’t have the patience to wait for a few weeks till they have established a baseline from which to adjust.

      Boom.

  6. Andy,

    Quick question for you…so I’m on day 5 of Week 1, and I set up my macros and everything according to your guide. The only thing that I didn’t do was this:

    “There is a school of thought that it can be beneficial for nutrient partitioning (and therefore body composition changes) to have more calories on the days you work out, and less on the days you don’t. Martin took this a step further by experimenting with higher carb/lower fat intake training days, and higher fat/lower carb intake rest days, while combining it with morning fasts.”

    So far I’ve been eating the same exact overall amount of calories and macros for each day, so my question is at what point should I make the transition to that^^? Is it important enough that I should even be worrying about it?

    1. Hi Holden. Any point you feel comfortable doing it. If you’re entirely new to this then I’d leave things as you are for now while you get used to it all.

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  8. I feel very frustrated by the nutritinal indurstry. Well i have been trying for the longest to lose here and there and i finally came to the conclusion that my way of cutting corners was horrible by over exercising and not eating enough. I did interment fasting for almost 2 years everyday until i stopped losing. Its been such a roller coaster of staying away from so many foods and killing my body with No results. Its been 11 years since i lost the major weight. Now im wanting to do macroa because i see so many people having good results. I feel lost!!! Im 5″10 female 32, 164. What do you think im doing wrong.
    I want to do iifym and was told to cut and tone i needed to be at 1500 calories. It was a killer yesterday and all week trying to stay that low as i was very hungry..

  9. Hi Andy, in your experience have you learned any special insight into issues with mood and general energy levels when cutting? I ask because my mood quickly deteriorates when cutting, with depression and general lack of motivation setting in, and I’m wondering what might be the cause – or rather, if there’s a cause besides the obvious calorie deficit and if there’s something I ought to tweak.

    More specific details of my situation: I’m approx 10% bf right now, trying to lose a few more lbs before a long, slow bulk. I took a diet break about three weeks ago. Since the break I’ve been losing approx .75 – 1.0 lb per week. Hunger typically isn’t an issue but I do get cravings, especially at night. My macros are on the lower fat side (~25%) because I tend to hate life even more without carbs; I don’t know if that’s a factor.

    So when it comes to dieting and mood, any thoughts on where to adjust to seek improvements? Is it indicative of overtraining? Wrong macro setup? Too severe calorie deficit? Or just the price that must be paid to reach my goals?

    1. Hi Matt, sure, a deficit affects some people harder than others and we’re limited as to what we can do about that in honesty.
      – You’ve had a diet break.
      – Hunger isn’t the issue. (So we don’t need to look to switch to more filling foods.)
      – You’ve already played around with your carb/fat intake and determined you feel better with relatively higher carb/lower fat intake.
      – So the only logical next thing is to simply take the fat loss slower/reduce the calorie deficit.

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  14. Hello Andy. I simply love this page.
    I have a question for you. I know it is recommended by cutting to do calories +10% / – 30%.
    The problem is that when I do -30 it is hard for me to keep diet. But 0% / – 20 % is easier for me. The same with recomposition I feel a bit better when I do +10% / -10% instead of +20% / -20%.
    The Question is: can I do it in this way, I mean does it have any negative influence on my results in comparition to +10 / – 30% for cutting and +20 / -20% for recomposition. Besides I’ve noticed that some IF calculator propose also 0 / -20% for cutting.
    The most important for me is what do you think about it.

  15. Hi! I just found your site since starting IF and IIFYM so I’m not sure if these questions are already answered so I do apologize. I started about 2 months ago. I am a mother of 3(had my last child 18 months ago) Because of my busy schedule with kids and work I usually break my fast between 2:30 and 3:30pm and sometimes eat my last meal/snack between 7:30-9:30pm.
    I am already at my goal weight so that’s not the issue, just trying to look my best and get rid of the baby flab I have around my mid section and legs. I am just wondering since this isn’t the 16/8 time frame how much is this affecting my results? I do HIIT 3 days a week and lift, somewhat, heavy weights 2 days a week(squats, lunges) I occasionally run/walk with my kids throughout the week and I have a pretty physical job as well, so I am pretty much on the move all day long. I am on a 1406 calorie a day.
    Thank you for any help!
    Best, Jenna

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