How to Calculate Macros for Fat Loss

How to Calculate Macros for Fat Loss

If you really want to shred the fat and nothing else has worked, despite continually working out, it’s almost certainly due to your diet and macro-nutrients split.

Unfortunately until recently the majority of diets focused on reduced fat options which can lead to a low-calorie/high sugar diet restricting what your body needs to function. Ultimately leading to your body storing fat, weight fluctuation and a reduction in metabolism.

To strip the body of fat, you need to build muscle. If you are in a calorie deficit and not getting the right macro nutrient split you are at risk of lean muscle mass loss.  Calculating your macros based upon your height/weight and exercise level will ensure your body gets what it needs whilst making small adjustments which can reduce your overall body fat, build lean muscle mass and preserve your metabolic health. If you’re interested in learning how you can do this then keep on reading…

The first thing you need to calculate is how much energy does your body need if you are in a state of rest for the day?  This is called your BMR basal metabolic rate. To calculate you need to know your weight/height and age.

Weight and height are important as these calculate your mass.  Your age is also important as you get older your muscle mass will reduce.


The calculation for this is as follows (Mifflin St Jeor Equation):

Male BMR = 10 x weight + 6.25 x height – 5 x age + 5
Female BMR = 10 x weight + 6.25 x height – 5 x age – 161

This gives us a total amount of calories you will burn at a state of rest. For example:

Weight(KG) – 63.5
Height (CM) – 172
Age – 34

My BMR would be 1379.

Your BMR excludes physical activity.  So to find out how many calories you burn a day based on your activity level, you need to calculate the following.  BMR x activity factor, where – 

1.2 sedentary
1.375 light activity (1-3 30 minute exercise sessions per week)
1.55 – 3-5 a week
1.75 – 6-7 a week
1.9 athlete

For example sake, if my activity level is 1.75, this would give me 2,413 calories that I am burning per day with my current activity level.

Now we need to consider your goal – do you want to lose weight/gain weight.

We know that it takes a deficit of 3500 calories to lose 1 lb of fat, which is 500 calories per day to lose 1 lb per week.  If this is your goal subtract 500 from your 2,413 (in this example) and this gives you your daily goal (1,913). I would advise not to go lower than 800 calorie deficit per day as this could lead to muscle loss.


Now to calculate your macro split.

The calories for macronutrients are as follows:

Protein = 4 kcal /g
Carbs = 4 kcal / g
Fat = 9 kcal/g

For fat loss you need a high protein diet. The range for protein can be from 0.8 – 1.5g per lb of bodyweight.

For this example lets go with 1lb which is recommended for a fat loss goal.

Protein = 1g/lb (bodyweight) = 140g protein/day = 560 cal  (based on 140lb person as per above example)
Fat = 0.4g/lb (bodyweight) = 56g fat/day = 504 cal (based on recommended 0.4g of fat per lb of bodyweight for fat loss)
Carbs = 1913 – 560 – 504 = 849 calories  (divide by 4 = 212g carbs per day)

My target macros would be 140g Protein / 56g Fat / 212g Carbs to lose 1lb of fat per week.

You can tweak slightly if you know how your body responds, for example if you’re looking to define muscles you may want to increase protein to 1.5g per lb.  Once you have your macros split you need to start tracking them to make sure you are hitting your targets. You can use an app like Lifesum, you can track your food intake daily and it will breakdown your macro nutrients for you, you can even set your targets which you have created above.

All new subscribers to my website receive a FREE downloadable BMR & Macro calculator and a FAT LOSS Cheat Sheet.  My Macro calculator shows you how you can tweak your macros to increase or reduce your protein intake based on your goals.  Subscribe to receive yours for free.

Kellie xo


4 thoughts on “How to Calculate Macros for Fat Loss”

  • Is this accurate??? I am 30, weight 150 and height 5’3 and my activoty factor is 1.2 so results to loose weight is to consume 1142 calories…….and protein:150g=600 cal…..fat: 60g=540 cal……now my carbs is wat throws me off…it gives me 5 grams of carbs…is this right?? Plz help me figure this out

    • Hi! Yes its right, your total number of calories you consume at rest is 1369, with your activity level of 1.2 this gives 1643, so if you try to do a calorie deficit of 500 it leaves you with 1142, combined with a high protein diet of 1g per lb it doesnt leave you with much left. There are 2 options you can do which will help you with fat loss.
      Option 1 – Change your calorie deficit to 300 per day and put protein to 0.8g per lb of bodyweight.
      This gives you:
      Total 1344 calories per day split by:

      Protein, 480kcal, 120 grams
      Fat, 540kcal, 60 grams
      Carbs, 324kcal, 81 grams

      Option 2 – Remain with a 500 calorie deficit, but reduce fat intake to 0.3g per lb of bodyweight and protein at 0.8.
      This gives you:
      Protein, 480kcal, 120 grams
      Fat, 405kcal, 45 grams
      Carbs 258kcal, 64 grams

      Both options will help you achieve fat loss with a high protein diet,option 1 will just be a little slower but may be easier to achieve. I would go with what you think could be more realistic for you.

      I hope this helps! 🙂 x

  • I think your calculator it doesn’t work , I’ve calculated your bmr and it say that you should eat 1719 calories not 1379 like you say , sow I wonder if it’s just a mistake ! Tell me please what shold be the bmr for a female 34 years 168 height and 76 weight I’m just curious !! And a 1.375 activity level !!

    • Hi there! Using the example I have given in the post, the calculation is as follows:

      For a female – (10xweight kg) + (6.25xheight cm) – (5xage) – 161

      Which equates to – (635)+(1075)-(5*34)-161 = 1379

      For yourself, your BMR is:

      (760)+(1050)-(170)-161 = 1479

      With your activity level this gives you – 2034 calories you burn each day.

      I hope this is useful, let me know if you have any further questions.

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