How Many Calories Should I Eat? A Dietitian Weighs In

While I do not believe everyone needs to count calories, I do think it can be helpful to have a rough idea of your calorie needs, especially at the beginning of a health journey.

The key word here is rough.

Your calorie needs are not a perfect number. They are an estimate. But a good estimate can give you a helpful starting point.

In this post, I am going to show you how to calculate your daily calorie needs using a simple equation, how to estimate your maintenance calories, and how to adjust that number if your goal is weight loss or weight gain.

Before You Calculate Anything

Calorie counting is not for everyone.

If you have a history of disordered eating, obsessive tracking, or a difficult relationship with food and body image, please be careful with calorie tracking.

• You do not need to count calories to eat well.
• You do not need to count calories to improve your health.
• And you do not need to count calories to lose weight.

I have a full post on whether calorie counting is right for you here: Should You Count Calories?

But if you have decided that you would like to calculate your calorie needs, this guide will walk you through it step by step.

What Are Calories?

Calories are a measure of energy.

Your body uses energy every single day to:

• Keep your heart beating
• Keep your brain working
• Breathe
• Digest food
• Move around
• Exercise
• Maintain body temperature
• Repair and build tissue

Even if you stayed in bed all day, your body would still need energy to keep you alive.

That baseline amount of energy is called your basal metabolic rate, or BMR.

What Is BMR?

BMR stands for basal metabolic rate.

This is the estimated number of calories your body would use at complete rest.

In simple terms, it is the energy your body needs just to keep you alive.

Your BMR does not include exercise, walking, cleaning, working, cooking, or any other daily movement.

That is why your BMR is not the same as your total daily calorie needs.

What Is TDEE?

TDEE stands for total daily energy expenditure.

This is the estimated number of calories your body uses in a full day.

Your TDEE includes:

• Your BMR
• Daily movement
• Exercise
• Digestion
• General activity

This is also often called your maintenance calories.

Your maintenance calories are the approximate number of calories you would need to eat each day to maintain your current weight.

Average Calorie Requirements

You will often see 2,000 calories per day used as a general guide.

In the US, 2,000 calories per day is used as a general reference on nutrition labels.

In the UK and Ireland, average guidance is often around:

• 2,000 calories per day for women
• 2,500 calories per day for men

But these are only averages.

Your actual calorie needs may be higher or lower depending on your:

• Height
• Weight
• Age
• Sex
• Muscle mass
• Activity level
• Health status
• Goals

This is why a generic 1,200 calorie meal plan or a random calorie target from the internet is usually not the best place to start.

How To Calculate Your Calorie Needs

The simplest way to estimate your calorie needs is:

1. Calculate your BMR
2. Multiply it by your activity level
3. Adjust based on your goal

Let’s go through each step.

Step 1: Calculate Your BMR

One commonly used equation is the Mifflin-St Jeor equation.

For women:

BMR = 10 x weight in kg + 6.25 x height in cm - 5 x age in years - 161

For men:

BMR = 10 x weight in kg + 6.25 x height in cm - 5 x age in years + 5

This gives you an estimate of your resting calorie needs.

Step 2: Choose Your Activity Level

Once you have your BMR, multiply it by an activity factor.

This gives you your estimated maintenance calories.

Sedentary: Little exercise, desk job, low daily movement

BMR x 1.2

Lightly active: Light exercise 1 to 3 days per week or some regular walking

BMR x 1.375

Moderately active: Exercise 3 to 5 days per week and a reasonably active lifestyle

BMR x 1.55

Very active: Hard exercise 6 to 7 days per week or a physically active job

BMR x 1.725

Extra active: Very hard training, physical job, or training twice per day

BMR x 1.9

This final number is your estimated maintenance calorie intake.

Example Calorie Calculation

Let’s use an example.

A woman is:

• 35 years old
• 165cm tall
• 70kg
• Lightly active

First, we calculate her BMR:

10 x 70 + 6.25 x 165 - 5 x 35 - 161

That gives an estimated BMR of around:

1,395 calories per day

Now we multiply this by her activity factor.

Because she is lightly active:

1,395 x 1.375 = 1,918

So her estimated maintenance calories are around:

1,900 calories per day

This means she would likely maintain her weight around 1,900 calories per day.

But somewhere around that number.

How To Calculate Calories For Weight Loss

If your goal is weight loss, you generally need to create a calorie deficit.

That means eating slightly fewer calories than your body uses.

But the key word is slightly.

I usually recommend starting with a small deficit of around:

200 to 400 calories per day

or roughly:

10 to 15% below maintenance

So if your estimated maintenance calories are 1,900 per day, a reasonable weight loss range might be:

1,615 to 1,700 calories per day

For most people, this is much more sustainable than cutting calories aggressively.

You do not need to eat the exact same number every day either.

Think of your calorie target as a range.

Some days you may eat at the lower end.

Some days you may feel hungrier and eat at the higher end.

That is completely normal.

How To Calculate Calories For Weight Gain

If your goal is weight gain, you need to do the opposite.

Instead of eating below maintenance, you eat slightly above maintenance.

A good starting point is usually:

200 to 400 calories above maintenance

So if your maintenance calories are around 1,900 per day, a weight gain range might be:

2,100 to 2,300 calories per day

If your goal is to gain muscle, I would also focus on:

• Eating enough protein
• Strength training consistently
• Getting enough sleep
• Increasing calories gradually
• Monitoring progress over time

The goal is not just to gain weight quickly. The goal is to support muscle gain as much as possible.

How To Choose The Right Activity Level

This is where many people accidentally overestimate their calorie needs.

Most of us like to think we are more active than we are.

A good rule of thumb:

If you work at a desk, drive most places, and exercise a few times per week, you are probably lightly active or moderately active.

If you have a very physical job, walk a lot, and train most days, you may be very active.

If you are unsure, choose the lower activity level first.

Then track what happens over the next few weeks.

Your body will give you better feedback than any equation.

How To Know If Your Calorie Target Is Right

Once you calculate your calorie target, use it for 2 to 4 weeks and monitor what happens.

Look at:

• Your weight trend
• Your hunger
• Your energy
• Your sleep
• Your cravings
• Your digestion
• Your training performance
• How realistic it feels

Do not judge your progress based on one day.

Your weight can fluctuate because of:

• Salt intake
• Carbohydrate intake
• Menstrual cycle changes
• Stress
• Poor sleep
• Constipation
• Exercise soreness

So instead of obsessing over daily changes, look at your average trend over a few weeks.

When To Adjust Your Calories

If your goal is weight loss and your weight is not changing after 3 to 4 weeks, you may need to adjust.

Before reducing calories further, ask yourself:

• Am I being consistent most days?
• Am I tracking accurately enough?
• Am I having more extras than I realize?
• Has my activity level changed?
• Am I retaining water from my cycle, stress, or exercise?

If you are being consistent and your weight trend is still not moving, you could reduce calories slightly or increase daily movement.

A small adjustment is enough.

You do not need to slash another 500 calories overnight.

If you are losing weight too quickly, feeling exhausted, or constantly hungry, your calories may be too low.

In that case, I would increase calories slightly.

Do You Need To Eat Less On Rest Days?

Not necessarily.

Some people like to eat more on training days and slightly less on rest days.

That can work.

But many people find it easier to keep calories fairly consistent across the week.

Your weekly average matters more than hitting the perfect number every single day.

If you are very hungry after a hard workout, eat a little more.

If you are less hungry on a rest day, you may naturally eat a little less.

You do not need to micromanage everything.

How Accurate Are Calorie Calculations?

Calorie calculations are not perfectly accurate.

They are estimates.

The equation gives you a starting point, but it cannot fully account for your genetics, hormones, metabolism, muscle mass, daily movement, or lifestyle.

Even when a dietitian calculates calorie needs, we are still using equations and clinical judgment.

The most accurate methods of measuring energy expenditure are done in specialist settings, and they are not something most people can access in normal life.

So please do not treat your calorie target like a magic number.

Treat it like a starting estimate.

Then adjust based on real-life feedback.

The Biggest Mistake People Make

The biggest mistake I see is choosing a calorie target that is far too low.

For many women, this looks like jumping straight to 1,200 calories because that is what an app suggested.

But eating too little often leads to:

• Constant hunger
• Low energy
• Cravings
• Poor training
• Feeling irritable
• Thinking about food all day
• Overeating later

A calorie deficit should not feel like a punishment.

You should still be able to eat proper meals.

You should still have energy.

You should still be able to concentrate.

You should still be able to enjoy your life.

My Dietitian Advice

If you want to calculate your calories, calculate your maintenance first.

Then make a small adjustment based on your goal.

• Do not guess.
• Do not jump to the lowest number possible.
• Do not copy someone else’s target from TikTok.

Use your own body, your own lifestyle, and your own data.

And remember that calories are only one part of the picture.

For weight loss, I would still focus on:

• Protein at each meal
• Plenty of fiber
• Lots of fruit and vegetables
• Balanced meals
• Strength training
• Daily movement
• Sleep
• Stress management
• Consistency

Calories can give you the framework.

Your habits are what make it work.