It is hard to avoid calories! They are detailed on food labels and there are a wide range of applications which help us to log and count our calorie intake. Why are we so busy counting calories?! We do this to help control our food intake and manage our weight. The theory (if we were robots – but happily we are not!) is that reducing our energy/calorie intake leads to weight loss. If we take in less energy than we need, then logically, we will have to find the additional energy we need from our (fat) stores, and our extra weight will melt away……
What are calories?
A calorie is quite simply a unit of energy. Our bodies need energy for growth, repair, maintenance, and the calories in food provide this energy.
A calorie (small ‘c’) is defined as:
The amount of heat required at a pressure of 1 standard atmosphere to raise the temperature of 1 gram of water 1° Celsius.
Food Calories (with a big C) is the equivalent of 1,000 little calories, also known as Kilocalories (Kcal).
When we talk about food calories, we mean Kcals or Calories.
How to calculate the calorie content of foods
Different nutrients have a different calorie content. The three main food groups, proteins, carbohydrates, and fats have different calorie values. 1 g of either protein or carbohydrate contains 4 calories, while fats contain 9 Calories per g. Alcohol contains 7 Calories per g…. The good news is that vitamins and minerals do not contain any calories!!!
Foods contain a mix of different macronutrients, so the calculation of the calories in a particular food involves means working out the amount of fat/carbohydrate and protein it contains and then multiplying this amount by the calories per g for each food group.
How does counting calories help with weight control?
The average woman (who is moderately active) requires 2000 Calories a day of energy. The average man (also moderately active) requires 2500 Calories.
You need a calorie deficit to lose weight!
In theory, 1 kilogram of fat contains 7,000-ish Calories. To lose 0.5 kg a week, you should therefore aim to consume 3500 Calories less over a week, a reduction of 500 calories a day (i.e., 1,500 Calories for women instead of 2,000). Again, this theory assumes you are a robot which happily we are not!
What are the disadvantages of counting Calories?
An awareness of calories can be helpful for both portion and weight control. Yet not all calories are equal. Calories do not indicate nutrient status. For example, a bar of chocolate containing 200 kcals has a vastly different nutrient profile to 200 kcals of almonds. The almonds contain protein, fibre and unsaturated food, all nutrients which are good for our health. The chocolate contains sugar and saturated fat, nutrients which in excessive quantities are not good for our health.
The Calories in a food do not consider digestibility and satiety. Protein rich foods have less ‘caloric availability.’ Some foods, such as protein and fibre are harder for our digestive systems to break down. This means that even if we eat 100 kcals of protein, there is only 70 kcals left to be absorbed once digestion is complete because 30 kcals are used in breaking the food down for digestion.
The longer a food takes to digest, the more it is likely to keep us feeling full longer and reduce snacking (and therefore consuming additional calories!). Protein, fats, and fibre rich foods are digested slower than sugars and starches, helping to optimise our feelings of satiety.
A last point to underline is that if you focus eating for your health, consuming a wide range of proteins, unsaturated fats, wholegrains and fruits and vegetables, you may well find there is no need to count calories!