The concept of calories as a simple measure of the energy in our food has been a cornerstone of conventional weight control advice for decades. However, a new understanding of nutrition and how our bodies use calories from food reveals that it is much more complicated than we might have thought. The idea of the body as a furnace and food as its fuel was popularised in the 19th century by Wilbur Atwater. He deduced that there are three main components, or macronutrients, with which we can calculate the calorie content of any food: protein and carbohydrates contain 4 calories per gram, while fats contain 9.
But when we consider how food is consumed, we encounter the first problem. For example, an orange is mainly carbohydrate or sugar, but when we drink orange juice, our body will absorb the sugar quickly because there is no digestion required. However, when we eat orange segments, it takes energy for the digestive system to work on the fibre and extract the sugar. Therefore, our body does completely different things with it, despite the same calorie hit.
This knowledge has implications for nutrition and weight control advice. Orange juice causes a more rapid spike in blood sugar levels than the orange segments, and regular surges in blood sugar can lead to weight gain and other health problems. Therefore, balancing diet and exercise is much more complicated than simply counting calories. Nutritionists now recommend a balanced diet with a focus on nutrient-rich whole foods such as fruits, vegetables, lean proteins, and whole grains. Additionally, exercise is crucial for overall health and weight control, but it is important to understand that exercise can increase our appetite and potentially lead to overeating.
In conclusion, while calories remain a useful measure of the energy in our food, the way our bodies process calories is more complex than we once thought. A balanced diet and regular exercise are essential for overall health and weight control, but we must also consider the quality of the food we eat, the way we eat it, and how our body responds to it.