How to Calculate Your Calorie Deficit

Posted on 06. Apr, 2009 by in Nutrition

When I had my measurements taken last week, I also had to re-adjust my calorie intake because it changes with my body composition. Because of this, I also had to re-calculate my calorie deficit. If you’ve been trying to lose weight for awhile, you’re probably familiar with this concept. But, a lot of people are either doing it wrong (eating too much or too little calories) or just don’t know how to calculate their calorie deficit at all.

The concept behind the calorie deficit is simple. You figure out how much you need in order to maintain your current weight (this is your maintenance level) then, you reduce the amount of calories that you eat in order to lose weight. In his book, Burn the Fat, Feed the Muscle,” Tom Venuto says that you should have, at most, a calorie deficit of 30% under maintenance level. This would mean that if your maintenance level is 2,000 calories then, you can eat 1,600 calories to lose weight but not less than that because it slows down your metabolic rate if you reduce your calorie intake even further. Take note, that Tom also mentioned 7 reasons to not undereat when you’re dieting and this is only one of them.

Ok, if I haven’t confused you already, let me give you an example of how to calculate your calorie deficit. Keep in mind that a lot of factors affect your maintenance calorie levels but, to simplify the discussion, I will just focus on the formulas.

The first, simple formula is by using multipliers of Total Daily Energy Expenditure (TDEE also known as maintenance level):

  • For Fat loss: multiply by 12 to 13 calories per lb. of bodyweight
  • Maintenance (TDEE) = 15-16 calories per lb. of bodyweight
  • Weight gain = 18 to 20+ calories per lb. of bodyweight

So, if I wanted to lose weight, I would multiply my weight by 12. Let’s say my weight is 117 lbs. My TDEE would be 1,755 calories (117 lbs x 15) so I’d want to eat 1,404 calories (117 lbs x 12) in order to have a calorie deficit. Take note that this formula is suitable only for people who are “average” which means that they are not grossly overweight or thin. Also, it doesn’t take into account the Basal Metabolic Rate (BMR) which can vary greatly among the general population depending on your body composition, height, age, etc.

This leads me to the next discussion: the Harris-Benedict formula. This takes into account the BMR which means that it will apply to the general population and a lot of people can calculate their calorie deficits this way.

Before I proceed, you can download the calculator that I use here:
Calorie Deficit Calculator

Back to the calculation…

Men: BMR = 66 + (13.7 X wt in kg) + (5 X ht in cm) – (6.8 X age in years)
Women: BMR = 655 + (9.6 X wt in kg) + (1.8 X ht in cm) – (4.7 X age in years)

So, if I have the following statistics:

  • Weight: 117 lbs = 53.18 kg
  • Height: 5’4″ = 162.56 cm
  • Age: 27 yrs old

My calculation would look like this:

BMR = 655 + (9.6 X 53.18 kg) + (1.8 X 162.56 cm) – (4.7 X 27) = ~ 1,331 calories

Because my BMR is my calorie expenditure if I didn’t perform any exercise, I have to multiply it to an activity factor depending on how active my lifestyle is or how much exercise I perform in a week.

Based on the following activity factors:

  • Sedentary = BMR X 1.2 (no exercise)
  • Lightly active = BMR X 1.375 (light exercise 2-3 times a week)
  • Mod. active = BMR X 1.55 (moderate exercise 3-5 days a week)
  • Very active = BMR X 1.725 (rigorous exercise/sports 6-7 days a week)
  • Extr. Active = BMR X 1.9 (rigorous daily exercise/sports & physical job)

So, if I just go to the gym 3 times a week with strength training and intervals, I would multiply my BMR by 1.55 which will give me about 2,063 calories (1,331 calories x 1.55). Now, I just have to figure out what is 30% of 2,063 which is about 619 calories. I would then subtract 619 from 2,063 in order to give me my calorie deficit of 1,444 calories. If I don’t want to lose that much weight, I would reduce the 30% to 20% and so on.

Again, this formula will not apply to people who have extremely low body fat or extremely high body fat (overly obese) but it will be fine for the general population. For the purpose of this post, this should help a lot of people figure out their calorie requirements in order to know their calorie deficit. There is another more specific formula that takes into account the lean body mass when calculating caloric needs but that one deserves a post all by itself.

Here is the file again. I created this for myself and I’m making it available to you in order to make the process a lot easier. Enjoy!

Calorie Deficit Calculator

To dowload the file, right click and save as.

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  • http://www.getfitwithkelley.blogspot.com Kelley

    This is a very good post and you do a great job explaining what a calorie deficit should look like and how to calculate it. It is timely for me because I find that as much as I would like to just eat clean at 90% or higher compliance and not count calories, it’s not that easy for me. I find I do much better when I am tracking calories, and this is a good reminder of how to stay on course with that.

  • admin

    Hi Kelley, this is definitely what I started doing again – count calories and really focus on the macronutrient ratios. I find that I get better results by doing this too instead of just winging it. I’m glad you found the post helpful.

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  • james

    Hi,

    your excel sheet is impressive but the male calculation is wrong! the formula for men does not take the age into consideration and over estates the final figure

    regards,

  • admin

    Thank you for catching that, James. I already fixed it.

    Anna

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  • anthony

    what is the password to use the spread sheet? i keep clicking on it and it tells me i need a password to un protect it

  • admin

    Hi Anthony, there’s no password. You just need to type in your information in the red boxes. The yellow boxes are protected to protect the formula.

    Please let me know if this works for you.

    Anna

  • http://pathtofatloss.com annadornier

    Problems fixed, guys. Thanks for the input!

  • Brittany

    Thanks for the information, I used the Harris-Benedict equation listed above but then after a brief search I found and calculated my BMR using the Mifflen- St Jour equation and there's a three hundred calorie deviation between the two after the additional calculations of activity level and weight management. Which would you reccommend using or would you suggest splitting the difference??

  • http://pathtofatloss.com annadornier

    Hi Brittany, you know since I wrote this article. I've learned so much and

    from my experience, I say treat these as estimates as they will always be

    estimates. They will always have about a 10-15% error.

    So, I suggest to adjust for those errors and eat about 15% below the average

    of what each number tells you. For example, if one tells you 1,200 calories

    and the other says 1,500, take the middle of them which is about 1,350 then

    subtract 15% for errors which comes out to about 1,150.

    One thing to remember on a daily basis is you will always make errors in

    calculations. So, it's safer to eat much less calories than what the

    nutrition labels tell you.

    I hope this helps!

    Anna

  • Ben

    Here is a scientific comparison of the Harris-Benedict v/ Mifflen-St. Jour http://www.indianjmedsci.org/article.asp?issn=0019-5359;year=2008;volume=62;issue=7;spage=283;epage=290;aulast=Amirkalali   I hope the link works for you. But in summary the Harris-Benedict is much more accurate.

  • http://pathtofatloss.com annadornier

    I think you missed the point of the study you linked to. I am basically saying the same thing about the Harris-Benedict formula as what the study found. They are saying both formulas have clinical significance at the individual level. This means they both have their importance when it comes to calculating ouwr energy needs.

  • Nina fray

    Hi, I’ve downloaded your Calorie Deficit Calculator, but it says the cells in the excel file are protected. 

  • http://pathtofatloss.com annadornier

    Hi Nina, make sure you are only edit the numbers and not the formula. If it still doesn’t work, I can e-mail you a working version. Just let me know!

  • JulieAnn

    I just want to thank you for explaining all this bc it makes more sense to me now!

  • Guest

    Hello,
    Im a bit confused. The article states:

    So, if I just go to the gym 3 times a week with strength training and intervals, I would multiply my BMR by 1.55 which will give me about 2,063 calories (1,331 calories x 1.55). Now, I just have to figure out what is 30% of 2,063 which is about 619 calories. I would then subtract 619 from 2,063 in order to give me my calorie deficit of 1,444 calories. If I don’t want to lose that much weight, I would reduce the 30% to 20% and so on.

    When 30% is calculated, is that not the calorie deficit? 

    So 30% of 2,063 which is about 619 calories is the calorie deficit each day, eating  1,444 calories (2,063-619) daily gives a calorie deficit of 4,333 calories a week, which is very little over 1 lb lost per week.

    I am confused as to why/how the calorie deficit is calculated to be 1,444 calories?  and if that is correct, then is the suggestion to consume 619 to create a deficit of 1,444 calories?  Just seems like to little calories consumed and too much of a deficit.

  • http://pathtofatloss.com annadornier

     Hi, keep in mind that 30% is the most you can have as a deficit. You can adjust this deficit to be lower than that based on how fast or how slow you want to lose fat. I hope that makes it clear.

  • http://pathtofatloss.com annadornier

     You’re welcome! Glad this helps.

  • Earon

    It still doesn’t work

  • http://pathtofatloss.com annadornier

    I just sent you an e-mail with the file attached.