How many calories should I eat a day?

Keep reading to find out why numbers aren’t everything and how to build a balanced diet in line with the recommended calorie intake advice.

Key takeaways

• The calorie content of a food isn’t a sole indication of how healthy it is
• Looking at the nutrient content of a food is far more reliable
• How many calories you need will depend on your size, weight, and exercise volume
• Foods that contain an equal amount of calories are not necessarily equal
• Our bodies all react differently to different foods, regardless of their calorie content
• Counting calories is not always a sustainable way to lose weight

What are calories?

Calories are the measuring unit we use to quantify energy. When we talk about calories in the context of food, we are talking about how much energy is in a specific type of food.

There is a clear definition distinction between two types of calories that you need to know about:

• A ‘calorie’ or ‘cal’ (with a lower case ‘c’) is the amount of energy required to raise the temperature of 1 gram of water by 1°C
• A ‘kcal’ (kilocalorie) or ‘Cal’ (with an upper case ‘c’) is the amount of energy required to raise the temperature of one kilogram of water by 1°C.

When we talk about food…

When we talk about food, we use ‘kcal’ as our unit of measurement. This will tell you how much energy is in a specific type of food.

Proteins and carbohydrates both contain 4 kcal/g, whereas fats contain 9 kcal/g.

How many calories should I eat in a day?

Calorie requirements for adults are based on gender, age, weight, and activity level. It is not recommended to make calory-specific recommendations to children and teenagers as these variables vary greatly.

Adults

You may see the suggestion that females should consume no more than 2,000 kcals/day and males should consume no more than 2,500 kcals/day. 

Due to differences in height and weight, it’s more accurate to calculate calorific intake based on a person’s height and weight (using BMR).

If you’re looking for a rough estimate based on the average height and weight of both sexes, you can use the broader recommendations below:

• 1950-2250 kcal/day for adult females
• 2400-2700 kcal/day for adult males

Are all calories the same?

If you take 1000 calories of broccoli and 1000 calories of cake and water and heat them in a lab, they will appear equal. When you consume them however, they are not equal at all.

In practice, this means a person may feel more hungry and less satisfied by one food in comparison to another, even if the calorific content is the same.

This is because the two foods react very differently inside our bodies. For example, the ingredients in a cake communicate with our fat cells and disrupt hormone levels (the satiety hormone leptin and the hunger hormone ghrelin in particular) in a way that broccoli doesn’t.

Are calories everything?

No, they aren’t. Calories are an indication of the amount of energy in a food. As we’ve discussed, they are not a reliable way of gauging the nutritional value or ‘health profile’ of a food.

Counting calories and solely relying on them to plan what you eat could mean managing your diet too strictly. This can be unhealthy and lead to a calorie deficit where you actually eat more unhealthy and processed foods.

There are numerous different factors to weight loss and purely focusing on calories and being in a deficit isn’t a guarantee that you’ll lose weight or feel ‘healthy’.

Changing your perception of calories and looking at the content and nutritional profile of what you eat is a healthier way to make sustainable, long-term changes to your diet.

How do we burn calories?

We burn calories just by being alive.

Our body uses the energy we get from food to execute both the simple and complex processes that allow us to move, think, and breathe.

When we engage and push our mind and body further, we burn even more calories. If we’re exercising or exerting ourselves, we’ll need more calories because our muscles need additional fuel to facilitate this extra level of movement.

The science behind it all

Food molecules contain energy/calories that are stored in chemical bonds. When we digest, process, and metabolise these bonds, our body can then use the energy for anything and everything we do. This includes sitting still, resting, working, thinking, or exercising.

Does it matter when I eat my calories?

Eating little and often doesn’t give our digestive system rest. When we snack every few hours, we put extra demand on our internal systems and increase our risk of inflammation (an immune response to what the body believes to be ‘foreign bodies’ in our system) after we eat.

This practice of regular snacking also indicates to our body that it doesn’t need to burn any fat or use internal energy resources because it has fuel coming in regularly.

If we’re looking to lose weight, we’re better positioned getting our body to burn what it has. 

We can do this by eating regular meals with sensibly timed non-eating windows in between. For some people, placing a greater emphasis on protein, fibre, and carbohydrate consumption also helps.

Eating less calories to lose weight

To lose weight, we need to be in a calorie deficit. This means our body needs to burn more calories than it consumes.

Whilst this sounds simple in theory, the weight loss equation becomes more complicated in practice.

Some people may be eating less food to the point where the body’s biological mechanisms kick in and adapt so it doesn’t use our energy reserves because there is a scarcity of food.

It’s important we don’t starve ourselves of energy if we’re trying to lose weight. Eating balanced meals regularly that are moderately sized (focusing on protein and fibre rather than carbohydrates) can help the body to shed some of the extra weight it’s carrying.

Do I need to count calories to lose weight?

No, you don’t.

There are several factors that affect whether the body will start to lose weight. It simply isn’t as simple as less calories in and more calories out.

The main considerations are:

• Stress levels
• Sleep
• Inflammation levels
• Nutrition
• Activity

We naturally need to consume more food when we exercise. If we increase exercise and reduce our food intake, we aren’t going to be able to sustain our ability to burn calories in the long-term.

We will have more successful results by looking at what we are eating and when. Timing our meals so we remain fuller for longer and adjusting the content of our food is a more reliable way of sustaining long-term weight loss progress than simply looking at calories alone.

Eating more calories to gain weight

As previously mentioned, it’s important to remember that not all calories are equal.

It’s almost always going to be more beneficial to put muscle mass on rather than fat (although we do need a certain level of fat in our diet) when talking about weight gain.

If you’re looking to lose weight, the common advice is to ensure you maintain a good level of protein intake. If you’re looking to increase your weight by putting muscle on, this becomes even more important.

When calculating a good level of protein intake, you should consider how much exercise you’re doing and how often you’re doing it. If you’re training regularly and looking to put weight on, consider enlisting the advice of a nutritionist to ensure you’re maintaining a healthy calorie surplus.

Calories and macronutrients

Macronutrients are the nutrients we eat in large quantities to source energy and make sure our body is functioning correctly and efficiently.

The main macronutrients are:

• Carbohydrates
• Fats
• Proteins

Different macronutrients have different amounts of calories. The calorie content of a macronutrient is measured in kcals.

Proteins and carbohydrates both contain 4 Kcal/g whereas fats provide 9 kcal/g. Just because fats provide us more calories, it doesn’t necessarily mean we need to avoid them if we are trying to maintain or lose weight.

We need to eat healthy fats (from oily fish, seeds, nuts, avocado, olives, and olive oil) as they provide the essential fatty acids that we need to consume for many functions in the body.

A balanced diet should contain a diverse source of macronutrients to make sure our body is getting all the amino acids, vitamins, and nutrients it needs.

What are empty calories?

Empty calories are calories that provide us with little to no nutrients.

These are usually found in refined carbohydrates such as sweets, fizzy drinks and other processed treats and crisps.

Consuming too many empty calories can lead to weight gain, nutrient deficiencies, and other serious health problems like obesity, type 2 diabetes, cardiovascular disease, and dental problems.

We recommend limiting your consumption of foods and drinks that are high in empty calories and focusing on nutrient-dense foods that contain essential vitamins, minerals, and nutrients instead.

The bottom line

Whilst calories are beneficial for giving us a rough idea of how much energy we’ll get from a good, they should never be relied on as a sole indicator for how healthy a certain food is.

When thinking about what a healthy diet looks like, we should use calories alongside the nutritional profile of a food to determine how beneficial it is going to be for our body.

If you’re still unsure what a healthy diet looks like, speaking with a nutritionist can help give you the tools and information you need to get started with a new, healthy diet that works for you and your lifestyle.

Last updated Monday 4 March 2024

First published on Monday 4 March 2024