WHEN you navigate the complex world of nutrition, the calorie feels thankfully simple. A direct measure of the energy in our food, calories are at the heart of conventional weight management advice. Eat too many, or don’t burn enough, and you’ll gain weight. Do you want to lose weight? Eat less and move more. As the saying goes, “a calorie is a calorie is a calorie”. However, dig a little deeper and you’ll find that it’s not that simple.
This idea of the body as a furnace and food as fuel was popularized by Wilbur Atwater in the 19th century. He deduced that there are three main components, or macronutrients, with which we can calculate the caloric content of any food: proteins and carbohydrates contain 4 calories per gram, while fats contain 9. Combine them and the result reports the caloric content in the food labels. everywhere.
But think about how food is consumed and you run into your first problem. Take an orange, he says giles yeogeneticist at Cambridge University and author of Why calories don’t count. An orange is mostly carbohydrate or sugar. “When you drink orange juice, your body will absorb the sugar [quickly] because no digestion is required,” says Yeo. However, eat orange wedges and it takes energy for the digestive system to work on the fiber and extract the sugar. “Physiologically, your body does completely different things with it, with the exact same calorie punch,” Yeo says.
Orange juice causes a more rapid rise in blood sugar levels than orange wedges, for example, and regular spikes in blood sugar…