Why You Need to Make Adjustments to Your Macros as You Diet

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

So you’ve gone to an online macro 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

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 the 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. Suboptimal macro ratio setting

Referring here to the three macronutrients: protein, carbohydrate, 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, a 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 fewer 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.’


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”

Metabolic Damage: Cause for Concern?

In short, no.

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 is 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. 

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About the Author

Andy Morgan

I am the founder of RippedBody.com, this is my sincere effort to build the best nutrition and training guides on the internet. Some readers hire me to coach them, which I've been doing online, via email, for the last seven years. If you're interested in individualized, one-on-one nutrition and training coaching to help you crush your physique goals, let's start the conversation.