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What Is A Calorie Deficit?

Calories are confusing, but they don’t have to be.

I find calories very controversial; it can be extremely confusing to know which calorie controlled diet to follow next or if we should actually be watching our calories like they are our favourite TV soaps.

What Are Calories?

For those of you who do calorie count or have calorie counted in the past, are you doing it to follow a diet regime, do you actually know what calories are? Put simply, when you eat or drink calories are the amount of energy that you have just consumed (1). So, when we eat food we are eating energy, or potential energy for the things we do known as physical activity. This energy from food and drink is measured in kilocalories and kilojoules (2). What we see on food labels and refer to as calories are the kilocalories (kcal). A calorie by definition is the equivalent to the amount of energy required to increase the temperature of 1Kg of water by 1℃ (2). Let’s just stick to thinking of calories as energy and what calories we don’t burn have the potential to be stored as energy or fat as we best know it.

Why Do We Need Calories?

We need calories to live, as simple as that; everything we do requires calories from breathing to running marathons. The energy we get from food and drink is used to keep us alive and to keep our organs functioning normally (1), calories sound pretty essential right? I want you to think beyond calories being just having a role in your weight. The energy made available to us from food is used to meet certain needs of the body including the maintenance of body temperature, respiration, muscle function and protein synthesis (2); we need calories!

How Many Calories Do I Need?

Whilst there are suggestions around what both male and females require in terms of the number of calories per day, it is important to understand that our energy requirements vary between individuals: age, gender, physical activity levels and our body composition (3). Males are generally seen to have higher overall intakes of calories and macros in comparison to females (2):

  • 2,500 kcal per day for males (1)

  • 2,000 kcal per day for females (1)

As noted previously, different factors affect each individual and their calorie and macro requirements. Age affects the requirements too with studies showing that energy intake requirements decrease with age due to a reduction in lean muscle mass and being more sedentary (2). Different life events will alter your calorie requirements too. For example for females, it is suggested that during pregnancy more calories should be consumed (2).

What Is A Calorie Deficit?

You may have heard of a “calorie deficit”, especially if you follow Personal Trainer James Smith online. To understand a calorie deficit you need to understand energy balance. So, energy balance is the relationship between energy intake, energy expenditure and energy storage. Simply put, if we eat more than we burn off we gain weight as we will have a positive energy balance and this energy will be mainly stored as fat. In contrast, if we eat less than we burn off we result in a weight loss and we will have a negative energy balance2. If you burn more calories than you consume this is a calorie deficit (4), hence the association between weight loss, fat loss and calorie deficit.

Calorie Deficit and Weight Loss

A calorie deficit can be achieved through reducing the number of calories you eat or increasing the number of calories you burn. It is recommended that a 500 calorie per day calorie deficit is sufficient for weight loss (4). However, it is important to note that any small reduction in what you eat (energy intake) and what you burn off (physical activity) can help you to lose weight and for you to continue to maintain your weight (5) once you have achieved your target. The smaller, more sustainable changes can help you to come away from the yo-yo dieting approach. So often I say to new clients what is it you actually want to achieve, what are your goals, what is the main reason for changing your diet or exercising more? 9/10 this answer comes back as “I want to lose weight” in some fashion or another, there is the old “tone up” or “drop a dress size” but ultimately it comes down to body composition and what we look like.

Recently I have been holding group workshops to delve deeper into the “why” people want to lose weight and how they are actually measuring it. For many weight loss means fat loss yet so many people only measure their weight, what they are on the scales in terms of the whole number. I try and encourage people to either take measurements, photos or measure their body fat and muscle percentages to know exactly what they have lost.

In contrast to the approach of smaller changes, rapidly reducing your calorie intake can cause you to decrease your muscle mass and actually slow your metabolism (6): not the intended goal when you want to lose weight and tone up! In addition to muscle loss, rapid calorie restrictions can cause nutrient deficiencies, fatigue, weaken the immune system and even reduce fertility (7). It is important to note the sensitivities and triggers around restricting calories and the linked onset of eating disorders (8).

Calories and Exercise

After increasing your physical activity or exercise you may experience being more hungry and feel you are in need of more calories! This increase in energy intake after a workout could be down to the increased fat oxidation (fat burn!) and research shows more active people are more likely to eat more following a workout (9). The more active you are you may eat more but the good news is research also shows that you are less likely to eat high calorie foods compared to less active people! (9)

What Are The Health Benefits Of A Calorie Deficit?

As I mentioned earlier, a calorie deficit can lead to a negative energy balance or weight loss. Evidence shows that there are some health benefits to weight loss that include high blood pressure, the risk of heart disease, muscle pain including back pain and even fertility issues (10). Long-term calorie restriction has been shown to reduce the risk for developing type 2 diabetes by improving insulin sensitivity and reducing fasting glucose concentration (11). Whilst calorie restrictions or calorie deficits can lead to weight loss, it is important to maintain a healthy weight and be aware that being underweight too has health problems (9).

How Can We Monitor A Calorie Deficit and Weight Loss?

Sadly we cannot select where we lose fat from13, if we could wave the magic wand and just say I want to lose it from here but not here, trust me I would have created the perfect plan by now! That being said a calorie deficit will help us to lose overall body fat (13). There are many apps that can help us to track our food and help us to create a calorie deficit, the most popular fitness app is MyFitnessPal. Other ways can be to self-monitor by keeping a food diary or an activity diary and research shows that keeping track using these types of diaries can an immediate reduction in your food intake. Being more aware of what you are eating can really help you to create the calorie deficit and lead to weight loss (14). Another approach to tracking your calorie intake or energy intake is using portion sizes: kitchen scales, measuring cups (15) or hand portion size guides.

Further Reading

Struggling to understand what macros are and how you can achieve your daily calorie target? Read all about them in one of my latest blogs “What Are Macros”

Article Written by Jade Mottley – Fitness & Nutrition Coach / Health Writer

Instagram / Twitter: @Jademottley


1 comentário

Membro desconhecido
02 de dez. de 2020

Great Article Jade

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