The calorie content of many supermarket-bought foods is stated on the packaging as part of the nutrition label. This information will appear under the “Energy” heading in kcal.

Every living organisms requires energy to grow and to function; without energy, living organisms would not be able to live. A Calorie is a measure of energy for both food and physical activity.

There are two types of calories: 

● A small calorie or cal is the amount of energy required to heat of 1 gram (g) of water by 1º Celsius (º C).

● A large Calorie (kcal) is the amount of energy required to raise 1 kilogram (kg) of water by 1º C. It is also known as a kilocalorie.

When we talk about eating and exercise, we often refer to the word “calories”. Menus at restaurants chain quote the number of calories in every dish. Treadmills tell you the number of calories burned. When we use the words “calorie or Calories” on nutrition labels, in supermarket food labels, during physical activity, on menus and calorie counters, we are actually quoting kilocalories. Calories in foods represents how much energy is contained in the food.

This article will use “calories” to refer to “kilocalories”.

Calories are units for energy. The body needs a certain number of calories to maintain its vital functions and provide energy for the body either at rest or during physical activity. When we eat foods, they are broken down to release energy (calories) which is either used by the body immediately or stored for later use, depending on the body’s needs at the time. When you eat more calories than you need, the body starts converting that unused energy into muscle (short-term storage) or fat tissues (long-term storage). But when you aren’t able to eat enough, your body will tap into these stores to fuel itself.

How Do We Get the Energy

Food (and drink) is the only source of chemical energy for humans. Foods deliver energy (calories) in the form of proteins, carbohydrates, fats and alcohol (where present). Carbohydrates, which include sugars, often come from fruits, vegetables and grain products. Protein can be found in nuts, beans, legumes, fishes (including shellfish) and meats. And healthy fats often come from plant-based oils, nuts and seeds, some fruits and vegetables (avocados, olives…) and fatty fish. Not all energy from these nutrients is of the same quality. Below are the calorific values of main components of food:

● 1 g of carbohydrates contains 4 kcal

● 1 g of protein contains 4 kcal

● 1 g of fat contains 9 kcal.

Food often also contains two additional elements that affect their total calorie density, water and alcohol. They, too, have specific calories:

● 1g of water contains 0 kcal

● 1g of alcohol contains 7 kcal.

To create energy, our bodies convert these nutrients into glucose which then fuels all processes within the body. Carbohydrates (carbs) consist of hundreds of glucose molecules linked together, which our bodies can break down into individual units of energy. Proteins and fats, on the other hand, have to be converted into glucose. Proteins and fats have other uses in the body beyond providing energy. As facts, proteins are great for building muscle or antibodies to prevent sickness. Healthy fats (such as omega-3 fatty acids and monounsaturated fatty acids) help the body absorb vitamins and reduce the risk of heart disease and type 2 diabetes.

Ultimately, calories aren’t an enemy. Making the most of the energy we consume should be the key; this goes by incorporating some type of exercise (walking, gardening, running, strength training, etc…) into our daily life. Many people hoping to lose weight get obsessed with the numbers; but in reality, we should be thinking about calories in terms of our individualised energy needs. Whether you’re counting calories or ignoring them, those numbers are just a measure of energy.

In the UK, the government has introduced a mandatory calorie labelling in food businesses of a certain type, as part of an obesity reduction strategy to helping consumers make healthier decisions and to encourage businesses to reformulate the food and drink they offer and to provide lower calorie options to the consumers. “Calorie information, the reference to portion size, and the statement of daily calorie needs must be displayed clearly and prominently at the ‘point of choice’ for the customer.” Knowing the calorie content of food and drink can help ensure you’re not consuming too much. You can use the calorie information to assess how a particular food fits into your daily calorie intake.

On average, adult women should have around 2,000 calories a day (8,400 kilojoules) and adult men should have around 2,500 calories a day (10,500 kilojoules). We all need different amounts of energy (calories) from food to be a healthy weight. How much you need depends on many factors including how active you are.

The recommended intake of calories per day depends on several factors such as your age and also:

● your overall general health

● your physical activity demands

● your sex

● your weight

● your height

● your body shape.

To achieve or maintain a healthy body weight, balance the number of calories you eat and drink with the number of calories your body uses. If you’re gaining weight, it could mean you have been regularly eating and drinking more calories than you have been using. To lose weight, you need to use more energy than you consume, probably through physical exercise and continue this over a period of time.

However, consuming few calories for a prolonged period of time causes a person to become underweight leading to muscle atrophy, weakened immunity, and eventually, organ failure. Conversely, eating too many calories causes a person to become overweight then obese, increasing their chances of heart disease, type II diabetes, some cancers, other chronic diseases and even fertility issues; (It is good advice to consult a dietitian or nutritionist for weight gain or weight loss and also to know the calories your body needs, should you be worried about your health status).

Same calories but not equal: on the left refined sugar, on the right, unprocessed & natural fibre rich foods, plus vitamins, minerals & antioxidants.
Facts on Calories: 

● Calories are essential for human health. The key is consuming the right amount.

● Everyone requires different amounts of energy each day, depending on age, sex, size, and activity level.

● The time of day at which a person eats can shape how effectively their body uses calories.

Some researchers argue a large breakfast containing approximately 700 kcal combined with a lower calorie dinner is ideal for losing weight; Daniela Jakubowicz et al. (2013) reported that a high-calorie breakfast with a reduced intake at dinner is beneficial and might even be a useful alternative for the management of obesity. Therefore, when people eat could matter as much as what they eat.

● Foods high in energy but low in nutritional value provide “empty calories”; empty calories derive from foods that add little nutrients to the diet. These are generally those that come from added sugars and solid fats, as well as some processed oils and include carbohydrate-based desserts (cakes, cookies, biscuits, ice creams, donuts…), candy bars, sugary drinks (soda, some energy drinks and fruit juices), some meats, including bacon, sausages, and hotdogs. Consuming a lot of foods and drinks with empty calories can lead to weight gain and nutritional deficiencies. This simply means a person eating lots of empty calories may not get enough: vitamins, minerals, protein and essential fatty acids needed by the body to maintain its essential functions.

● Alcohol can also contribute “empty calories” to the diet.

● You want foods that deliver calories as well as other nutrients like vitamins, minerals, proteins and fibre. Foods low in energy but high in nutritional values feed the body. Few examples of such foods could be:

Vegetables, Legumes and Salads.

Vegetables are low-calorie and nutrient-rich foods that are closely associated with a healthy weight. They can form the base of any meal during the day either breakfast, lunch, snack or dinner.


High protein, low-calorie eggs may be the perfect breakfast food. Research has shown that those who eat a higher protein breakfast have reduced hunger throughout the day, increased satiety, and reduced production of the hunger hormone. Additionally, eggs are an excellent source of B vitamins and also provide vitamins A, D, E, and K. Eggs are also one of the best nutritional sources of choline, a key nutrient in cell growth and maintenance and in brain and bone health.

Whole grains

Eating whole grains (oatmeal, 100% whole-grain bread or pasta or brown rice) will keep you feeling full longer. That’s because whole grains have high fibre content and take longer for the body to break down compared to white grains like refined flour.


Berries, such as raspberries, blueberries, blackberries, and strawberries, are excellent options for those looking for low-calorie, filling fruit. With high fibre and water content, berries are also lower in natural sugars than many other fruits. They are packed with vitamins and nutrients, are antioxidant-rich, and even provide anti-inflammatory properties.

Sunflower seeds

Like nuts, seeds are calorie-dense, but super healthy since they’re high in healthy fats, fibre, and nutrients like vitamin E. Seeds are also linked to cardiovascular health and an improved cholesterol profile. Try sprinkling sunflower seeds on top of a low-calorie salad to add a nutritious crunch.

The human body needs calories to survive. Calories in food supply our bodies with the energy needed to sustain life. Without energy, the body’s cells and organs could not carry out any of the basic processes needed for living from protein metabolism to cell functions. We absorb the energy from the foods and drinks we consume.

Please note the information provided here should not take place of medical advice. We encourage you to talk to your healthcare providers (doctor, pharmacist, etc.) about your interest in and questions about what may be best for your overall health.


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Disclaimer: This blog provides information that should not take the place of medical advice. We encourage you to talk to your healthcare providers (doctor, pharmacist, etc.) about your interest in and questions about what may be best for your overall health.

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