Most South Africans love carbohydrates and because of this they often eat too much from this food group. With summer here many people may want to shed some winter kilos and the low carbohydrate diets sound appealing as there are so many (short term) success stories. We know that low carbohydrate diets containing less energy may have short term beneficial effects on weight, but concerns for the professionals have always been the long term implications of a low carbohydrate intake.
Let’s take a look first at what the term ‘low carbohydrate diet’ actually means. There are a number of different definitions for a low carbohydrate diet which is why it is no wonder that the general public may be confused:
1) A reduced or moderate carbohydrate diet that contains a minimum of 130g of carbohydrates per day (26% of a 2000kcal diet)
2) A low carbohydrate diet contains 30-130g of carbohydrate per day (less than 26% of a 2000kcal diet)
3) A very low carbohydrate or ketogenic diet contains less than 30g of carbohydrates per day (less than 10% of a 2000kcal diet)
Diets that provide 50-55% of total energy as carbohydrates provide 200-275g of carbohydrates in a 2000kcal energy diet. However, when you are trying to lose weight you will need to decrease your calories, which will naturally bring about a decrease of all the macronutrients (carbohydrates, proteins and fats).
We know that carbohydrates affect the blood glucose levels and that a continuous supply of glucose to the cells is what is physiologically needed (if you don’t put the glucose in your body will need to get it from its own sources – either muscle or fat). Remember though that carbohydrates consist not only of starches and sugars but also include fruits, starchy vegetables and milk. What’s more, eating proteins and fats (with the carbohydrates) helps to increase insulin secretion which can ultimately help with the blood sugar control. It is therefore evident that eating (low GI, higher fibre) carbohydrates regularly throughout the day together with some (low fat) protein or (healthy) fat is the best way to keep your blood sugar levels constant and allow your body to function best.
The World Health Organisation recommends that we have no less than 130g of carbohydrate per day as it is known that our bodies need a minimum of 130g of carbohydrate so that there is enough glucose for the central nervous system to work properly.
A meal plan of 130g of carbohydrates would look something like this (no proteins or fats have been included in this meal plan):
B – 1 cup cereal plus 1 cup milk
S – 2 x fruit
L – 1 slice bread
S – 1 x fruit plus 1 x yoghurt
D – ½ cup starch
An interesting study was published in the British Medical Journal this year which found that low carbohydrate, high protein diets used for many years on a regular basis are associated with an increased risk of cardiovascular disease. In the study over 43000 Swedish women, aged 30-49 years were followed up for an average of 15.7 years. The researchers found that a 20g decrease in daily carbohydrate intake and a 5g increase in daily protein intake would correspond to a 5% increase in overall risk of cardiovascular disease.
We do need more long-term studies, specifically to determine the minimum and maximum amount of carbohydrates that would be safe and effective. However, in the meanwhile it is beneficial to practice balanced eating (following the food based dietary guidelines) and not to be influenced by media reports suggesting high protein diets with unknown long term side effects.