Should You Trust That Calorie Calculator?

“So I went to this website to calculate my calories/macros and it gave me this much to eat. Is that right?”  - Concerned individual sliding into my DM’s (maybe you).

Here’s the short answer: maybe.

If you were expecting, a yes or no answer, I’m sorry. That answer is accurate. That calculator could be right or it could be completely wrong. That’s just how it is.

I’m glad I get asked about the accuracy of calorie calculators so often. I guess that means people are starting to understand again that how much you eat matters. The whole “calories don’t matter” thing was getting pretty annoying and is pretty much on par with the Flat Earth movement when you consider all the scientific evidence and you know...that whole energy balance and the laws of physics thing.

crowder calories.jpg

But I’m not here to present on whether you should or shouldn’t count calories to help you lose fat and weight. Calorie/macro counting works for fat loss but so do other methods and diets as long as they help you maintain an energy deficit. You can decide if counting works for you by how consistent you are at doing it. After all, that’s ultimately what matters in the long run.

I am here to clear the air about what a calorie/macro calculator is and is not as well as how you can use what a calculator tells you to reach your nutrition goals. Here’s the long answer to that original and seemingly straightforward question.


Is that calculator right? The Answer is still maybe.

All calculators are estimates and attempts to PREDICT energy needs. They cannot determine the exact calorie/macronutrient intake needs for an individual with 100% accuracy. There are simply too many factors at play like:

  • Gender

  • Age

  • Height

  • Activity

  • Lean body mass or body fat levels

  • Current diet composition

  • Diet history

  • Current health status

  • Medications taken

  • Genetics

  • Even climate!

They’re based on data collected during experiments from general populations of people to form an average and reasonable prediction for caloric needs, but there are always exceptions and outliers to these predictions. Individuals vary and it's impossible to know everyone's exact needs.

They're also entirely based on the truthfulness of the info you feed into the calculator.

Some formulas require certain parameters like body fat percentage which most people don’t know to any degree of certainty and most body fat measurements tools (calipers, InBody machines, bathroom scales) aren’t all that accurate to begin with.

Many require you to personally assess your activity level or how much you move throughout the day. This generally tends to get grossly overestimated. A 2014 study found that a large proportion of individuals, overestimated their physical activity. The people who overestimated tend to already be healthy and had lower BMI so those individuals perceived they were more active than they actually were (Source). 

For all of the reasons I mentioned, no calorie calculator can ever be 100% correct.


Are Calorie Calculations still useful? Absolutely.

All initial calculations of calories or macros are starting points to help you eat a consistent amount food for a period of time. By eating a consistent amount, you can determine if that was not enough or too much energy intake depending on what happens to your body as a result of following the recommendations. From there, you can make changes by tweaking the caloric intake either up or down to help keep you on track with reaching your goal.

For example, if I ate 2900 calories for several weeks and my weight stayed roughly the same over a long period of time, I could say that 2900 calories may be enough to maintain my current weight. From there, I could experiment and give myself more or less food to see if there was a change.

True story: that’s dieting and nutrition in an overly-simplified nutshell—make a small change and see what happens.  


A calorie estimate isn’t Captain Save-a-Diet.

A calorie count isn’t going to provide everything you need to be successful. Calories matter but there’s more to nutrition than just that.  It’s very likely you’ll need to adjust multiple aspects of your eating habits, lifestyle and environment for best results and create long-lasting change.

A calculator definitely isn’t going to help you if you don’t follow what it suggests. Yes, that calculator could be totally wrong, but you won’t know that for sure if you’re only semi-following it. The #1 rule for using calorie calculators or dieting in general is to be honest with yourself about your adherence to the plan. If you’re not consistently sticking to the numbers, you can’t blame the calculator.

Let’s say a calculator told you to eat 2000 calories to lose weight. You were tracking your food and logging 2000 calories Monday through Friday and then on the weekends you completely stop tracking and go H.A.M. on some food. You know damn well you can’t say with any honesty you were sticking very closely on those days. So if you’re not seeing results, it’s not the calculator's fault at that point.

If you’re counting calories/macros and aren’t seeing progress, the first place you need to look is your adherence. Measure and log everything you eat just to make sure you’re sticking to the plan. If it turns out you weren’t staying very close, then clearly your first item of business is to get back on track (yes even on the weekends). If you still can’t figure out why you’re not seeing results and can’t manage to break through the plateau, then get some help from a good nutrition coach

Things don't have to be perfect to work...just consistent

Knowing that calorie calculators aren’t 100% accurate, your intake doesn’t have to be perfect to still work.

If a calculator tells you to eat 2000 calories, you don’t necessarily have to be perfect and eat 2000 calories on the dot every single day. If you try to do that, you’ll just drive yourself crazy. Give yourself some (keyword SOME) wiggle room and most of the time get pretty close.

Consistency is going to be the most determining factor for success or failure. Understand consistency works both ways. If you consistently deviate from the plan, i.e. eat tons more food on the weekends, that’s likely going to work against you.



A good rule of thumb is to adhere 80-95% of the time. Just make sure it’s really 80-95% :) Higher adherence will give you better a indication that things are working or not but don’t stress out with the occasional, once-in-a-while slip-ups.


But what if I don’t FEEL like the numbers are working?

It’s not wise to rely on feeling like things are working. KNOW if that shit is working or not!

Most people mess up their nutrition by relying on their current emotional status to make a decision. That usually never works out well. Make your decisions based on the outcomes and data instead.

Provided that you are eating consistently, in order to truly determine if the amount of calories or set of macros is right for you and your goals, you must observe, record and track the changes that are happening to your body. Record all relevant and useful data and use the data as evidence to make a decision on what to change about your intake.

Check out this article I wrote on all the metrics other bodyweightyou can observe and record to know if your nutrition plan is working.

Use that data to make an informed decision on whether you should make an adjustment to what the calculator told you.

For example, if you’re following the calculator and losing weight quickly, but feel like shit and have no energy, maybe you should add some more calories back to see if your energy improves and you can still lose weight. Or just keep starving yourself, because that's really cool 😒

Or what if you’re trying to lose weight but struggling. In fact, you’re getting bigger in the mirror, the scale is going up, and your belly is spilling over your clothes now when that wasn’t the case before. If you’re truly and honestly following what the calculator is telling you to do, then it's time to switch gears. You’re likely taking in too many calories and you should try to lower the amount to see what happens.

Use data and common sense to make your decisions!


Changes don’t happen overnight. Be patient.

By far the biggest mistake people make with nutrition is not giving things enough time to work. Regardless of where you get an initial prescription for calories, macros, or eating habits, you have to give the plan enough time.


Your body changes slowly and it doesn't like to change. So just following a calorie count for a few days isn't going to give you the results you're wanting. Stop looking for the quick and easy way. Whatever comes out of it usually isn't worth a damn. Substantial body composition changes and actual fat/weight loss takes on the order of weeks not days.

So if you decide to use a calculator to figure out how much you need to eat, don’t even consider saying it doesn’t work unless you’ve been consistently sticking to it and recording results for at least two or three weeks.

Two to three weeks is generally enough time to observe changes or trends in the data you're tracking. You can see if things are moving in the direction you want. If things aren't moving in the right direction, then you know you need to change something about what you’re doing.


And now my favorite internet calorie calculator...

There are some pretty useful nutrition calculators out there on the interwebs but I like this calorie calculator the most for several reasons:

  1. It’s easy to use. It walks you through the process of inputting what the calculator needs. In my opinion, it helps you estimate your activity level better than other calculators out there.

  2. It allows you to set a goal weight and goal date which is very useful for planning and seeing how long it may take you to reach your body goals

  3. It helps you plan how to increase your daily activity to help you lose.

  4. It graphs your estimated progress! The inner nerd in me loves this feature and it’s helpful to see how your results compare to the estimates. If you’re way off base from the estimates, then have an honest look at your adherence. Note: Switch to expert mode to see the graphs

  5. It accounts for metabolic adaptation. The more we restrict calories and the more body fat/weight we lose, the more our bodies adjust internally to compensate (Source). The body doesn’t like change and this calculator takes that into consideration. I don’t know of any calorie calculators that take that into account.

  6. It was developed by some smart folks at the National Institute of Health. Nuff said. 

The only downside I can think of is that it doesn’t automatically calculate your macronutrient (protein, carb, fat) intake but you'll still need your estimated calories even if you're wanting to track macros. 

Here’s a link to the calculator

And a video tutorial on how to use it:



  • All calorie calculators provide only estimates of your intake. They give you a starting point and it may not be “right”.

  • The only way you know if these numbers are right for you is if you adhere to the guidelines for a few weeks and see what happens.

  • Don’t drive yourself nuts trying to be perfect with your adherence, just do your best to get close most of the time and continuously work on improving your habits and lifestyle to support your nutrition.

  • Track all relevant data on what’s happening to your body.

  • Use that data to adjust your intake as you continue to work towards your goals.




G Godino, Job & Watkinson, Clare & Corder, Kirsten & Sutton, Stephen & J Griffin, Simon & Mf van Sluijs, Esther. (2014). Awareness of physical activity in healthy middle-aged adults: A cross-sectional study of associations with sociodemographic, biological, behavioural, and psychological factors. BMC public health. 14. 421. 10.1186/1471-2458-14-421.

Hall KD, Sacks G, Chandramohan D, Chow CC, Wang YC, Gortmaker SL, Swinburn BA. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011 Aug 27;378(9793):826-37.

Rosenbaum, Michael, and Rudolph L. Leibel. “Adaptive Thermogenesis in Humans.” International journal of obesity (2005) 34.0 1 (2010): S47–S55. PMC. Web. 17 May 2018.

Stefan GJA Camps, Sanne PM Verhoef, Klaas R Westerterp; Weight loss, weight maintenance, and adaptive thermogenesis, The American Journal of Clinical Nutrition, Volume 97, Issue 5, 1 May 2013, Pages 990–994,

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