How many calories are needed to lose weight? This is a question that many people ask when they are trying to lose weight.


The answer is that it depends on a number of factors, including your current weight, your activity level, and your goals. If you are relatively inactive and want to lose a few pounds, you may only need to reduce your calorie intake by a small amount.


However, if you are overweight and want to lose a significant amount of weight, you will need to create a larger calorie deficit. The best way to determine how many calories you need to lose weight is to speak with a registered dietitian or other health professional. They can help you to develop a realistic and safe weight loss plan that meets your individual needs.


Click below to book in for a free consultation with one of our health professionals and we’ll help you understand how many calories are needed to lose weight specifically for you.


Whenever the discussion of weight loss comes up, one particular subject always follows…calories. The fact is, managing calories is difficult for most people. In the UK, ⅔ of the population is overweight or obese (ref).


So if you want to lose weight, transform your body, and improve your health and confidence, then calories are king.

But what exactly is a calorie? How many calories can you eat to lose weight? Where should your calories come from? How accurate are calorie calculators? What are the best ways for counting calories, and ultimately get results? We’ll answer these questions and more in this article. Keep reading to learn everything you need to know about how to count calories for weight loss.


What is a calorie?

A calorie (also known as a kilocalorie, or kcal), is not a ‘thing’, but rather it’s a measurement. To be more specific, a calorie is a measure of the energy needed to increase the temperature of 1kg of water by 1°C. Which is where we get the phrase ‘burning calories’ from.


The energy from calories is released when we eat through digestion. The energy gets stored in our body until we need it.


There are 3 main reasons we use energy:


  • Digestion: This accounts for 10% of the total energy we use
  • Physical activity: This uses up around 20% of our total energy
  • Basic functions: This takes up most of our energy, accounting for 70%. This includes everyday tasks, that you won’t even think about such as, well, thinking! Other functions include growing and breathing.


How do calories affect your weight loss?

When you don’t use the energy that gets stored in our bodies from the food and drinks you consume, a buildup of excess energy can happen, leading to weight gain.

How many calories can you eat to lose weight

In order to lose weight, we need to reduce the amount of energy that is stored in our bodies as fat. We can do this by either using more energy through physical activity or by consuming fewer high-calorie, poor quality foods and drinks. Eating more lower-calorie, high-quality foods and drinks will also help us to reduce the amount of energy we consume.


The number of calories we need to lose weight will vary depending on how much weight we want to lose. However, most experts agree that a safe and sustainable rate of weight loss is 1-2 pounds per week. So, if we want to lose 1 pound per week, we need to create a calorie deficit of 500 calories per day.


This can be done by reducing our calorie intake by 250 calories per day and/or increasing our physical activity levels so that we burn an extra 250 calories per day. Creating a healthy balance of diet and exercise is the best way to lose weight safely and effectively.

How many calories can you eat to lose weight

As well as asking how many calories are needed to lose weight, once you’ve lost weight you’ll need to know how many calories are needed to sustain your new weight which we’ll cover in the calorie calculator below.


To maintain our weight we need to find the right balance between consuming and using enough energy. But obviously, this is not always straightforward.

How many calories can you eat to lose weight

How many calories are needed to lose weight and where should your calories come from?

The calories we eat, digest and absorb come from one of three different macronutrients:


  • Carbohydrates
  • Proteins
  • Fats


A diet without a balance of these nutrients will lead to detrimental health effects, no matter what the number of calories is. How much you need of each one depends on your current weight and activity levels.


Macronutrient Calculator

Our free macronutrient calculator can help you figure out how much protein you should be aiming for each day. Just enter your weight, height, and activity level, and we’ll give you a personalized recommendation.


Remember, though, that everyone’s needs are different, so it’s always best to talk to your doctor or a registered dietitian before making any changes to your diet.


How accurate is calorie counting?

Unfortunately, Kcals on food labels can be misleading.


The calorie numbers are based on averages, for example, an apple can have a variance as much as 29%.

how many calories are needed to lose weight

So that can mean the 150kcal sandwich you had was actually 193kcals!


We know! Sorry…


Even when the calories we eat are accurate, we don’t absorb all of the calories we consume. For example, only 68% of the calories from almond nuts are absorbed (2). The rest go through our body system (as fibre) which is great for digestion but isn’t actually absorbed for energy.

how many calories are needed to lose weight

How we cook food can also affect the accuracy of calorie counting. Certain foods can increase the number of calories that can be absorbed, like potatoes which can have a difference of up to 100kcals (3-4).

how many calories are needed to lose weight

So is calorie counting a waste of time?

Absolutely not.


When setting out on a journey it’s useful to have some sort of map rather than no map at all, even if it isn’t 100% accurate it will help you set out in the right direction.

how many calories are needed to lose weight

Although calorie counting is not completely reliable, it can still be useful.


The key is therefore to be outcome-based and understand how to adjust your course if you aren’t heading in the direction you want.


Despite its limitations, knowing how much energy you need and how much energy is in certain foods is absolutely key, even if they aren’t perfect, they are a great start for helping you head in the right direction.


But it also exemplifies why it’s so important to stay consistent with your nutrition. Because when you are consistent you can be outcome-based.


For example, if you think you should be eating about 2500 calories a day to lose weight, but you aren’t, then you can try reducing your calorie intake by another 500 calories and then see what happens.


If you begin losing weight, then great!


If not, then you can try reducing your calories again by 500 calories until the weight slowly and sustainable starts to fall off.


We say only reduce by 500 calories because the body doesn’t like rapid change.


If you go from 2500kcals to 1000kcals in a week, your body will react by desperately trying to hold on to fat and increasing your hunger.


Changing calories has to be a gradual change like we’re trying to sneak our calories intake without the body knowing…


Just like our clients who use this approach have been able to lose weight sustainably, despite life getting in the way occasionally.


This is what science-based sustainable nutrition is all about.


“I’ve been working with Jamie since Feb 2019 and moved to Health by Science with him. I love working out at their gym, everyone’s super friendly.”


Over a 12 month period, David managed to lose over 10kg and record his lowest and healthiest weight in the last 25 years.


Lucy used to think that people like her were not meant to exercise. Lucy has now achieved results she never thought were possible.