What are calories? How to use them to reach your ideal weight

Calories how t o reach your ideal weight: weight loss retreat Spain

This month we are looking at how to reach your ideal weight. Calories are an important part of this discussion. So, in this article we look at what calories actually are, consider how to balance the calories that we eat (put in) with the calories that we use (put out), so that you can reach and maintain your ideal weight.

What is a calorie?

A calorie is a unit of energy. Most of us are used to seeing calories in relation to food – in simple terms, the amount of energy in an item of food or drink is measured in Calories.

Technically, there are two broad categories of calorie:

  1. The small calorie, or gram calorie (symbol: cal). This is defined as the approximate amount of energy needed to raise the temperature of one gram of water by one degree Celsius at a pressure of one atmosphere.
  2. The large calorie or kilogram calorie (symbol: Cal), also known as the food calorie and similar names, is defined in terms of the kilogram rather than the gram. It is equal to 1000 small calories or 1 kilocalorie (symbol: kcal).

In scientific terms, calories are a measure of the amount of energy it takes to raise the temperature of water by a specific amount. (This is calculated in a laboratory, when a specific portion of food is burned. Burning food releases energy, which raises temperature. This rise in temperature is measured using a thermometer). The unit of energy in the International System of Units is the joule. One small calorie (cal) is approximately 4.2 joules (so one large calorie, Cal, is about 4.2 kilojoules). In a nutritional context, the kilojoule (kJ) is the standard unit of food energy, although the kilocalorie is still in common use. The word calorie is popularly used with the number of kilocalories of nutritional energy measured.

This can get a little confusing as the words are often used interchangeably!

How many calories should we eat per day?

As a guide, to maintain a healthy body weight,

  • an average MAN needs around 2,500kcal (10,500kJ) a day
  • an average WOMAN, that figure is around 2,000kcal (8,400kJ) a day.

However, these values can vary depending on age, size and levels of physical activity, among other factors. See the section below on Basal Metabolic Rate (BMR).

How do I know how many calories are in food items?

By law in the UK and Europe, all packaged food should publish the contents of the food, in addition to the calories that the food item contains, plus other food values (including fat, salt and sugars). To allow you, the consumer, to compare different products, manufacturers should display the contents, per 100 grams. You will usually find the energy value listed in both joules and Calories (Cal or kCal)

Weight management and calories

Essentially to maintain an ideal healthy weight, the number of calories that you consume (IN) will balance the number of calories your body uses on a daily basis (OUT).

  • To gain weight, you need to eat MORE calories than you use.
  • To lose weight, you need to eat LESS calories than you use. (Note, this does NOT mean that you starve yourself. It is important to maintain a healthy diet to ensure you get all the nutrients that your body requires to function).

When thinking about weight management:

  • When we eat and drink MORE calories than we use up, our bodies store the excess as body fat. If this continues over time we may put on weight.
  • When we consistently eat and drink LESS calories than we use, our bodies start to weaken, hair loss might occur, anaemia can develop and so on.

There’s a psychological aspect to calorie-counting to discuss. If you look at your diet as a number of calories that you shouldn’t go over, then you tend to think of all foods as fine so long as they don’t push you over the limit. Eating only one 2,000-calorie meal (like a large portion of fish and chips) each day may mean you are meeting your calorie intake, however, this is not a healthy diet in terms of nutrition (vitamins, minerals, fat content etc).

Two foods might have an equal amount of calories, however they are often NOT equally healthy. When it comes to sugar, for example, we ingest either fructose or glucose. They’re both sugars, but our bodies react to them in very different ways, and the more sustainable source is glucose.

Eating healthy isn’t about maintaining a very strict calorie controlled diet, where you feel hungry all the time. It’s about eating healthy. At La Crisalida Retreats we believe that you don’t need a calculator to eat well so much as an awareness of the ratio you should eat, i.e. mindful eating.


We will look first at the calories that we put into our body. This is the starting point for many diets. As noted above, the number of calories that we require depends upon our age, gender and lifestyle.

Calories in typical foods

There is lots of information on the web about the food in each food item. Below I have picked out a few popular items from a plant-based diet as a rough guide to understanding calories in foods. To make food items comparable we show the average calories per 100 gram (unless otherwise stated):

  • Apple: 47 kcal
  • Banana (1/2 large): 95 kcal
  • Berries: 25-30 kcal
  • Dates (6): 203 kcal
  • Broccoli: 34 kcal
  • Carrot: 35 kcal
  • Kale: 33 kcal
  • Potato (small/ medium baked): 235 kcal
  • Avocado (1/2): 276 kcal
  • Celery (3 sticks): 7 kcal
  • Lettuce: 10 kcal
  • Sweet potato (small/ baked): 150 kcal
  • Lentils: 105 kcal
  • Beans (kidney, pinto etc): 100 – 130 kcal
  • Tofu: 73 kcal
  • Oil (olive, sunflower, sesame): around 135 kcal
  • Nuts (50g): 306 – 344 kcal (varies depending upon the nut)
  • Seeds (50g, pumpkin, sesame, sunflower): 288 kcal
  • Buckwheat, bulgar wheat, millet: 350 kcal
  • Brown rice: 282 kcal

You can see that the amounts vary quite dramatically. However, please remember, it’s not just about calories. What is not shown in the simplistic look at calories per food item is the nutritional value of the foods.

The Calorie Density Scale:

Calorie density (also known as calories per kilo), is how much energy, i.e. calories, is provided per unit measure of food.

Calorie-dense foods, such as fat and refined sugars, provide many calories in a small amount of food. Low calorie density foods, like fruits and veggies, provide only a small amount of calorie in a larger volume of food.

As a rough guide 1 gram of:

  • fat contains 9 kilocalories
  • alcohol contains 7 kilocalories
  • carbohydrate contains approximately 4 kilocalories
  • protein contains approximately 4 kilocalories

Thinking about calories and density, you can imagine the amount of food needed to provide the same amount of calories and how it would fill your stomach.

500 calories of oil will fill the stomach by only a fraction, whereas 500 calories of fruits and veggies will fill the stomach, meaning you feel fuller for longer.


There are two main elements to the body using up energy. i.e. calories

  1. Basal metabolic rate
  2. Exercise and other daily activities

Basal metabolic rate (BMR)

The basal metabolic rate is the number of calories that our body needs to function whilst at rest. When we are resting, our heart is beating, we breathe, our mind is working, liver functioning and so on – all of this requires energy (calories).

Everyone’s BMR can differ. You can find out your BMR using a BioImpedance Analysis machine (BIA). We can influence our BMR through lifestyle choices, e.g. taking regular exercise will help to raise our BMR. Muscles take more energy than fat, so have greater muscle mass in your body will mean you have a higher BMR.

Calories burned – typical values per exercise

Each time we exercise, it takes calories (energy) to make that exercise happen. The amount of calories burned for each type of exercise will vary depending upon the weight of the person – larger people tend to burn more calories.

As an idea, here are some of the calories used in one hour of exercise (by someone weighing 73kg / 11 stone 7):

  • Aerobics: 365 kcal
  • Leisure cycling (<10 mph): 292 kcal
  • Dancing (ballroom): 219 kcal
  • Hatha yoga: 183 kcal
  • Running (5 mph): 606 kcal
  • Swimming (laps): 423 kcal

How to eat sensibly – plating up food

Rather than continually counting calories, you can take a simpler approach to thinking about what you put on your plate. Forks over Knives give a great suggestion based on a traffic light system.Traffic light system for what plantbased foods to eat for weightloss

For more information see (external link Forks Over Knives).

How can I find and maintain an ideal healthy weight?

In this section we give you some suggested actions going forward to help to achieve and maintain a healthy weight:

  • Always eat breakfast: Skipping breakfast won’t help you lose weight. You could miss out on essential nutrients and you may end up snacking more throughout the day because you feel hungry.
  • Eat regular meals: Eating at regular times during the day helps burn calories at a faster rate. It also reduces the temptation to snack on foods high in fat and sugar.
  • Eat lots of vegetables and fruit: Fruit and veg are low in calories and fat, and high in fibre – three essential ingredients for successful weight loss. They also contain plenty of vitamins and minerals. Be aware of too much fruit though as it contains fructose, which is still sugar.
  • Get active: Being active is key to losing weight and keeping it off. As well as providing numerous health benefits, exercise can help burn off the excess calories you can’t cut through diet alone.
  • Drink lots of water: People sometimes confuse thirst with hunger. You can end up consuming extra calories when a glass of water is really what you need.
  • Eat high-fibre foods: Foods containing lots of fibre can help keep you to feel full, which is perfect for losing weight. Fibre is only found in food from plants
  • Read food labels: Knowing how to read food labels can help you choose healthier options. Use the calorie information to work out how a particular food fits into your daily calorie allowance on the weight loss plan. The fewer the ingredients the better, and if you can´t pronounce it, it probably shouldn´t be in your body!
  • Don´t stock junk food/drinks at home: To avoid temptation, try to not stock junk food at home, such as chocolate, biscuits, crisps and sweet fizzy drinks (remember, you can still drink calories!). Instead, opt for healthy snacks, such as fruit, unsalted rice cakes, oat cakes, unsalted or unsweetened popcorn, and real fruit juice.
  • Cut down on alcohol: A standard glass of wine can contain as many calories as a piece of chocolate. Over time, drinking too much can easily contribute to weight gain.
  • Plan your meals: Try to plan your breakfast, lunch, dinner and snacks for the week, making sure you stick to your calorie allowance. You may find it helpful to make a weekly shopping list. Drinks or snacks you have count towards your daily energy total. If you eat more for your breakfast, lunch or evening meal, you may need to drop a snack later in the day to stay on track.

Weight loss retreats

La Crisalida offer weight loss retreats that run all year around. By combining juicing or eating healthy plant-based food, with daily walks, yoga and other exercise classes you can start to see changes not only in your weight, but also in your body shape. Contact us for availability. More articles are available on the blog and you can also read about our activities here.

To your health and wellbeing.

About the author

Lisa is one of the founders of La Crisalida Retreats. She is an Epidemiologist, therapeutic hatha and yin yoga teacher and also teaches mindfulness meditation. Lisa has studied NLP and hypnosis, as well as nutrition (she designs the menus).