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  • Writer's pictureHolly Mills

Unlocking Weight Loss Success: The Ultimate Guide to a Healthy Calorie Deficit for Women

Everywhere you turn there’s another video spouting about how you need to be in a calorie deficit if you want to lose weight...

But what the heck even is a calorie deficit?

And how do you create a healthy calorie deficit?

Well - don’t worry, I’ve got you covered.

Over the next few minutes, I’m going to teach you everything you need to know about creating a calorie deficit.

Why you need to create a calorie deficit

If you want to lose weight, the fundamental thing you need to do is create a calorie deficit.

That’s where calories in are lower than calories out.

That leaves an energy imbalance (or a deficit) and that energy has to come from somewhere.

So your body goes to its stored energy (fat cells) and uses that instead.

So the only time you need to be in a calorie deficit is if you want to lose weight and reduce your body fat levels.

Calories in

Calories in just means anything you eat.

Wine, chocolate, crisps, lettuce, fish cakes - you name it.

If you eat it, it’s classed under calories in.

Calories out

Calories out is a little bit more complicated.

There are 4 things we need to consider.

BMR - This is your Basal Metabolic Rate

Now this is how many calories you burn by existing. I like to think of these as your Nothing But Netflix calories.

If you did nothing but sit and watch Netflix all day - you’d burn this number of calories.

We can’t really change this number long-term other than when you’re bodyweight changes.

The heavier you are, the more calories it takes to exist. The lighter - well the fewer calories you need to exist.

Thermic effect of food - how many calories you burn by eating

Eating food causes you to burn calories.

Your body needs to digest what you’ve eaten - and that ‘costs’ calories.

Thermic effect of activity - how many calories you burn by doing purposeful exercise.

Think gym, HIIT class, going for a run - any purposeful exercise you do - that’s what’s included in your Thermic Effect of Activity.

This number is always lower than you’d expect. A 30 minute strength training gym session only burning around 100-200 calories (Harvard Health Publishing)

Non-Exercise Activity Thermogenesis - NEAT - how many calories you burn doing everything else

Your NEAT calories are the calories you burn by moving your body.

Walking, fiddling, doing the washing up, talking with your hands - all these ‘cost’ calories.

This is the easiest thing to influence - that’s why walking daily is so highly encouraged.

Calculating your calorie deficit

With all that in mind, to create a calorie deficit you need to know two things -

Your calories out

Your calories in

To work out your calorie output, take your current bodyweight and do the following calculation

Lbs x 10 = BMR (your Nothing but Netflix number)


KG x 22 = BMR (your Nothing but Netflix number)

Then multiply that number by your current activity:

  • Minimal Activity - under 3k steps per day x 1.2

  • Moderate Activity - 1-3 workouts per week, 7k steps per day x 1.5

  • Very activity - 10k steps+ and 3+ workouts per week x 1.7

This will give you your maintenance number.

From here - take away a set number of calories per day and aim to be consistent with it. This will give you your calories in goal.

Small deficit = -300 calories

Medium deficit = -500 calories

Large deficit = -700+ calories

NOTE: These numbers will get you started. The best feedback is from your body. If you’re not losing weight after 2 weeks of hitting these calories - you’re not in a calorie deficit.

Adjust your numbers until you are losing weight.

Which deficit is right for you?

The bigger the deficit - the harder it’ll be to maintain.


The faster you’ll lose weight.

Balance speed and sustainability for the best results.

The key thing to note is that if you want to lose weight for health reasons, it’s not about how fast you can lose weight. It’s about whether you keep it off.

So focusing on making long-term lifestyle and habit change is the KEY to success.

How do I track my calories in?

There are a few different ways to track your calorie intake.

Apps like My Fitness Pal or Nutracheck are useful tools.

But - you don’t HAVE to track calories.

There are other methods you can use - but tracking your calories is one of the easiest and most effective ways to track calorie intake.

Even if you don’t track your calories - your body still does.

Holly’s Take on a Healthy Deficit

My argument would be that a healthy calorie deficit is one that you can sustain.

There is no point going for a massive calorie deficit if you can’t sustain it for longer than a few days or if it promotes a cycle of undereating to overeating.

Does the quality of food matter - or just calories?

When it comes to creating a calorie deficit, what you eat doesn’t matter.

Your calories could be exclusively Jammy Dodgers and if you’re in a calorie deficit, you’d lose weight.


This would leave you very hungry and make it very hard to sustain.

So thinking about the quality of food does matter if you want to maintain your calorie deficit with ease.


That’s everything you need to know about calorie deficits.

Ultimately, a calorie deficit is when calories out are higher than calories in.

The size of the deficit will determine how likely you are to stick to it.

And if you want to make a long-term change, focusing on your habits is the easiest place to start.

Check out this podcast episode

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