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counting calories

The three essential nutrients produce different quantities of energy when metabolized by the body:

  • Protein produces 4kcal per gram (17kJ)
  • Carbohydrate produces 4kcal per gram (17kJ)
  • Fat produces 9kcal per gram (38kJ)
  • Alcohol also provides energy when metabolised (7kcal per gram = 29kJ)

A healthy diet should be low in fat. Obvious sources of fat, such as spreads used on bread and oil used in cooking, are easily seen and avoided, but there are many hidden sources of fat in the diet that can only be identified if you read labels carefully. Here’s how you should do this:

  • Read the list of ingredients. If fat appears near the top of the list, then it is present in the food in large amounts. Remember that fat may appear in a number of disguises: read the section on ‘Ingredients’ for a list of the words used to describe it.
  • Look at the nutritional information. International regulations stipulate that in order for a product to be called ‘low fat’ it must have less than 3g fat per 100g product. (‘Fat free’ products must have less than 0.15g fat/100g). If it has more than 3g fat per 100g, it is not low in fat!
  • Remember that ‘reduced fat’ does not mean low fat! Treat claims such as ‘90% fat free’ with skepticism: a closer examination of the labels will usually reveal that the food contains far more fat than you think!

As a rough guideline, a food is considered to be high in sugar if it contains more than 10g sugar per 100g of food. A food with less than 2g sugar per 100g is low in sugar. Unfortunately, as sugar is a type of carbohydrate, it is often not listed separately in the nutritional information, but grouped with total carbohydrate.

  • Ingredients are listed in order of mass, so the closer the sugar in the product is to the front of the list, the more sugar the product contains.
  • The words sugar and sucrose are interchangeable in South African legislation, but that doesn’t mean that there are not other forms of sugar in a ‘sugar free’ product. Sugar may also be described as glucose, dextrose, maltose, fructose, syrup, concentrated grape juice and corn syrup.
  • 5g Sugar is equivalent to 1 teaspoon. If you divide the total amount of sugar per portion by 5, you can work out how many teaspoons of sugar the food contains. For example, a strawberry flavoured milk contains 38.5g sugar per 250ml: this is equivalent to almost 8 tsp sugar! (38.5 ÷ 5 = 7.7)

A slice of bread contains an average of 15g carbohydrate. Keep this in mind when interpreting the total amount of carbohydrate per serving. For example, a microwave meal (Ravioli in a tomato sauce) lists the total carbohydrate content per 350g portion as 56g. This means that you would be eating the equivalent of almost 4 slices of bread if you ate the entire meal (56 ÷ 15 = 3.7).