How To Calculate Macros For Fat Loss


What are macros and how do you calculate macros for fat loss and cutting? Learn how to work out your own calorie and macronutrient targets.

If you’re trying to lose weight, then there’s a good chance that you’ve heard the term ‘macros’ being used.

‘How can I calculate my macros for flexible dieting?’

‘What are your macros?’

‘Does this fit my macros?’

Common questions that we get asked all the time.

In this article we’ll cover exactly what are macros and then how to calculate macros for cutting (as they say in the fitness industry). Let’s get to it.

What Are Macros?

calorie counting on a paper with calculator.

Macros is simply short for macronutrients. As the name ‘macro’ suggests, we require these food groups in large amounts in the diet. There are four macronutrients: protein, fat and carbohydrates and the fourth is alcohol, but we’re going to focus on the first three. So far, so good?

How many calories someone consumes per day depends on their macronutrient intake. Protein and carbohydrates have 4 calories per gram whereas fat, which is more energy dense, has 9 calories per gram.

Let’s work through an example. Say you look at a food label that has 10g of protein, 10g of carbohydrates and 5g of fat.

To work out how many calories are in that food we multiply the grams of protein (10g) by 4 + grams of carbohydrates (10g) by 4 + grams of fat (5) by 9 = 125 calories.

Here’s the deal.

There are also ‘micros’, short for micronutrients. Micronutrients include vitamins, several fatty acids and a number of inorganic elements. We need these in smaller quantities but they are essential for growth, repair and maintaining our cells.

How To Calculate Calories For Fat Loss

A portrait of young man have a great desire to eat a burger

Before you can get down to the specifics of working out what macros you need to start flexible dieting (that`s where you pick and track your own foods to hit your macronutrient targets), you need to first calculate your calorie target.

It’s important to remember that regardless of what approach you take, your calorie target is an estimation, not an exact number.

Even if you follow all our advice to the letter, it’s still an estimation and some tweaking may be necessary (that’s one of the advantages of having a nutrition coach, we can do the tweaking for you. Find out more here)

Anyway, there are several ways you can estimate how many calories you need to lose fat. We’re going to do it using a slightly more advanced way rather than simply multiplying your body weight by a number like some people may do.

Before We Can Start, I’d like You To Meet Jimmy

Jimmy is going to be our guinea pig, he wants us to be his flexible dieting coach so we’re going to work out his macros.

He’s a 30 year old male, weighing 80kg at 180cm and he hits the gym a couple of times per week. He has a desk job and he wants to know his macros for fat loss.

First off, we need to work our Jimmy’s calorie requirements.

We’ll use the Mifflin-St Jeor formula to estimate his Basal Metabolic Rate (BMR). This is essentially the amount of energy expended per day before we add in his activity levels.

There are several equations we can use but a study by the ADA (American Dietetic Association) found the Mifflin-St Jeor method to be pretty accurate. Here it is:

Men: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) + 5

Women: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) – 161.

So for Jimmy, our 30 year old male, weighing 80kg at 180cm. His BMR would roughly be: (10 x 80)+(6.25 x 180) – (5 x 30) + 5 = 1780.

Now Add Your Physical Activity Ratio

Now that we’ve worked out his BMR, we need to multiply it by a Physical Activity Ratio (the estimated cost of activity he does per day).

If you were working this out, you would need to multiply your BMR by:

1.2 if you do little or no exercise

1.4 if you do exercise a couple of times per week

1.5 to 1.7 if you exercise several times per week

1.9+ if you exercise every day or have a hard, physical job

Back to our example.

Jimmy trains a couple of times per week so we’ll multiply his BMR (1780) by 1.4. This gives us his estimated TDEE (Total Daily Energy Expenditure): 2492.

In order to lose fat, Jimmy needs to create a calorie deficit.

This means he needs to consume less calories than he needs per day in order to lose fat.

A 15% deficit is often a good place to start. With our clients, we may go higher or lower depending on their starting body fat levels, their goals and energy requirements.

Anyway, Jimmy’s calorie target to lose fat would be: 2118 calories.

All cool?

Now we know how many calories to aim for, let’s calculate some macros for cutting.

Calculating Your Protein Target

We’ll start with protein. A higher protein diet can be a great tool for fat loss. It helps preserve muscle tissue and it helps to keep you feeling full.

A good figure to aim for – when flexible dieting – is often around 2g per kg of bodyweight.

For 80 kg Jimmy, that would be around 160g of protein.

Struggling to hit your protein target? This is our favourite whey protein shake (apple cinnamon swirl flavour, soooo good!)

Calculating Your Fat Target

How much fat should you eat to lose fat largely depends on preference.

While the name “fat” might strike fear into the hearts of dieters across the land, you need a certain amount of fat in your diet to stay healthy.

Fat has a host of important functions in the body. Fats are essential for cell growth, repair, brain function and a host of other essential bodily functions!

Aiming for a fat intake between 0.7g – 1.2g per kg of bodyweight might be a good start.

On Jimmy’s flexible dieting plan, he is going to aim for around 1g per kg so that would be 80 g of fat for him.

Calculating Your Carbohydrate Target

So far we’ve worked out Jimmy’s total calorie target: 2118 calories.

His protein target is 160g

And his fat target is 80g

That means we now need to calculate his carbohydrate requirements.

To do this, we’ll first work out how many calories we’ve assigned already. Remember how to do this?

4 calories per gram of protein and 9 calories per gram of fat, right?

That means Jimmy has been assigned 1360 kcal so far (160×4)+(80×9).

If we subtract 1360 from his calorie target (2118) he is left with 758 kcal remaining for carbohydrates.

Divide this number by 4 (because there are 4 kcal per g of carbohydrate) then his carb target is 190g.

If this method was too complicated, listen to this: Lean Habits For Lifelong Weight Loss with Georgie Fear 

There you have it. Jimmy’s daily macros to lose fat would be:

2118 kcal = 160g protein, 80g fat and 190g carbohydrate.

What Now?


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We’ve shown you how to calculate macros, to start flexible dieting you need to go and start tracking your intake and aim to hit those targets! A good tool to track your macros would be My Fitness Pal.

What foods you eat are largely down to you. It would be a smart move to think of food quality first and foremost. Embrace those micronutrients!

Aim for nutrient dense, fresh, tasty foods that you love that are packed full of vitamins, minerals and fibre.

Flexible dieting or IIFYM (If It Fits Your Macros) isn’t about how much junk you can stuff into a meal plan. It’s about eating a range of nutritious foods (for the majority) that you love, that allow you to hit your macro targets, whist maintaining an element of flexibility.

Follow our guides above to estimate your macros, adjust as needed and start to make some fantastic fat loss progress.

How To Calculate Macros For Fat Loss, Flexible Dieting & IIFYM

Scott is the owner and founder of Food For Fitness. He is a fat loss coach, speaker and fitness writer with a masters (MSc) degree in Applied Sports Nutrition.