Making Your Calories Work For You

Making Your Calories Work For You

2nd March 2019

What are Calories?

Having discussed calorie and macro nutrient labelling with over 200 people in the last few months, I have heard quite a few interesting comments on calories and what different calories can and cannot do in our bodies. This has motivated me to write a few blogs under the title 'Making your calories work for you.'

A calorie (usually written as kcal on packaging) is a physical unit of thermal energy and is the term used to measure the energy derived from food and drink. The calorie value we see on food labelling or in food trackers such as MYfitnesspal are not derived from burning food and measuring the energy, but from chemical analysis of the protein, fat and carbohydrate in the food. The typical values below are used for conversion from a pure source of the macro nutrients -

  • 1g of protein contains 4 calories
  • 1g of fat contains 9 calories
  • 1g of carbohydrate contains 3.75 calories
  • 1g of alcohol contains 7 calories.

The only food or drink item that contains no calories is water. So, when we eat or drink anything else our body is taking in calories. It then does one of two things, it either burns them up or it stores them for use later. When our body stores calories for later use this is as both body fat and as muscle mass.

Our body burns up or uses energy through a number of functions, firstly through our basal metabolic rate (BMR), this is the energy it takes us to breath, pump our blood around our bodies, work our brain, digest food  and maintaining something called homeostasis. Then the one most of us think of, we burn them through physical activity. We can directly influence the energy used up by our bodies through physical activity by doing more or less exercise.

So how do we make the calories we eat and drink work the best for us?

Let's take an example of an adult who is burning up 2130 calories a day between their BMR and physical activity levels combined. If they eat 2130 calories everyday then their body weight will remain stable.

If they continue to burn of 2130 calories each day and start eating less calories everyday, they will lose weight as their body starts to use the stored energy to make up the energy deficit. On the other hand, if they start eating more calories on a regular basis their body will start storing this unused energy for later use. And if the energy this person is burning up on a regular basis does not later increase then they will permanently keep this excess weight. 

Are there any good or bad calories? No a calorie is a calorie is a calorie. And your body will store any excess calories you take in regardless of if they come from protein, fat or carbohydrate. 100 calories of carrots have the same effect on your weight as 100 calories of chocolate.

Are there good or bad foods then? No, but there are foods that are healthier to eat and more beneficial to our health than others. It is not just energy we get from food and drink, we must also take in other nutrients such as vitamins, minerals, amino acids and essential fatty acids. All of which are necessary to keep our body in good health and help to repair it when we have an injury or are ill. So those 100 calories of carrot will benefit our wider health more than 100 calories of chocolate.

Therefore, to make our calories work for us we need to ensure we have the right balance of calories going in and out. And that the calories we are taking in give us the best possible healthy balance nutrient intake.

The person discussed above could take their 2130 calories everyday as all chocolate or all carrots. In both these cases they would certainly be missing essential nutrients and would eventually become ill. They, and all of us, need to take a balance of foods from the food groups. The Eatwell Guide  is one way nutritionist illustrate to us how to get the right balance in our food and drink intake.

On the other side of the energy balance current recommendations are that adults take at least 90 minutes of moderate to vigorous activity each week. And for those using activity trackers 10,000 steps a day is a really good target.

I am going to return to calories and how to get the best out of them in future blogs and I hope you enjoyed this one.

Dr Laura Stewart

February 2019 

Main photo reproduced from Obesity World image bank.