It’s all Greek (yoghurt) to me- Understanding Energy

Flip over most food products and you’ll find the, sometimes intimidating, nutritional table. And at the top of that table we have an energy value- either displayed as calories (kcal) or kilojoules (kJ). These 2 words send a good proportion of us into a panic but few of us truly understand what these values are trying to tell us.

This is the second post in a blog series aimed at educating consumers on how to read, understand and utilise the information we find on our food labels. Next up- figuring out calories and kilojoules.

The idea of measuring energy in food is based on the concept that your body needs a certain amount of energy a day to get through the day. The energy content on the label tells you how much of this energy this particular food will provide. This value will either be measured in kcal (calories) or kJ (kilojoules). They both measure energy. Essentially it’s the like deciding to measure distance in kilometers or miles- same distance, different ways to measure it. South African labels will usually work with kilojoules.

It isn’t necessary to work with both of these values but it is essential to always make sure you’re comparing kcal with kcal and kJ’s with kJ’s. If you do need to change calories to kilojoules; it’s easy enough, simply multiply by a factor of 4.2. So 50 kcal is equal to 210Kj’s (50 x 4.2).

An important consideration when it comes to energy is portion size. Energy values should be given per 100g and then per portion size; which will vary according to the product. Simply comparing the energy value of 100g of the foods in question may be misleading because it doesn’t take into consideration the amount of food you’re likely to consume.

For example; 100gs of Bar One contains 415kcals and 100gs of almonds contains 575kcal. Based on the 100g energy value you’d think we’ve found a great motivation to include that Bar One.

Here’s where considering serving size is valuable. The chances of you eating 100g of almonds is very slim considering that that amounts to roughly 75 almonds. You’re more likely to eat around 15 almonds- which is about 100kcal. Compare that to a medium Bar One with a 55g serving size with an energy content of 228kcals; and your decision looks much different. Now your energy intake if you chose the almonds is 128kcal less- roughly the same amount of energy you’d find in a slice of whole wheat bread.

Another reason to pay attention to portion size is that what’s in the packet is not necessarily the portion size listed on the label. This often happens with biscuits.Although there may be 4 biscuits in the packet; the portion size on the label is a mere 2 biscuits. If you don’t pay attention to portion size -and realise that you need to double the kilojoule content listed per portion size on the back- you’ll miss the fact that you’re not eating a low energy snack but rather one packed with kilojoules.

Food decisions shouldn’t be solely based on energy content. Even without comparing the energy content of almonds and Bar Ones; we all know which one is the healthier choice. But understanding how to compare the energy content in foods still aids us in understanding what’s in the food we eat and how choice from what’s on our supermarket shelves.

Some food labels go one step further and tell you what percentage of your daily energy intake this food will provide you. This is known as the DRI (Daily Recommended Intake) or NRV (Nutritional reference Value). It’s important to remember that this recommended intake is an estimated value for any individual above the age of 4. It doesn’t take into account your weight, height, gender, age or level of activity. Rather use this value to identify high energy foods than should rather be avoided such as that large Bar One which is 21% of your DRI! Or a can of Coco Cola which is roughly 7% of the total amount of energy that your body needs in one day.

For more information regarding food labels and food choices; schedule a Supermarket session. Booking can be made online or by giving me call; contact details can be found on my website.