The short answer would be ‘it depends’.
If you have had even the tiniest of experiences in weight loss or ‘toning’ your body (i.e. building muscle) you would have been told to stick to your daily calorie target. You would also have been told about the concept of ‘calories in’ vs. ‘calories out’. In order to lose weight the calories consumed should be less than the calories used up.
Although this concept is very true and correct, simply looking at calories is not automatically going to give you good health (even if you’re achieving your fitness/weight loss targets!).
Why is that? Because each calorie has its own nutritional value. That means that, depending on its source, a calorie will have a different composition of nutrients (protein, carbohydrates, fats, vitamins, minerals and water). And so calories from fat will function differently in the body compared to calories from sugar.
Sugar, the simplest form of carbohydrates, requires very little digestion and goes straight into the bloodstream. Now, the body can only process the sugar at a certain rate and it also has a limit as to how much sugar should be circulating in the blood. Too much sugar in the blood can cause a range of serious metabolic derangements in the body and so our bodies try really hard to remove excess sugar from the bloodstream (in fact, our bodies work best when we have less than 1 teaspoon of sugar circulating in the bloodstream). And so the body will first use as much sugar as it can for energy and then the rest will be stored as fat.
On the other hand, calories from fats are released more slowly because fats take longer to digest and absorb (some say up to 8 hours!). This allows the body to use up the energy released from the fats in small batches, avoiding the flood of energy which then has to be stored as fat.
To make things more complicated, it is not just about the macronutrients (those required in large quantities) – proteins, fats and carbohydrates. We can think of these macronutrients as the fuel and building blocks of the body. However, it is the micronutrients (vitamins and minerals) which act as the gears that enable the body to use the fuel and function properly. Thus, a calorie which contains mostly macronutrients but little or no micronutrients is also of little use to the body.
And so we go back to the beginning – not all calories are made equal. If you’re just interested in weight loss, eating anything within your calorie target could still help you lose weight. However, in addition to losing weight you may also deplete the body of the vital minerals and vitamins, the gears of the body, which affect how your body functions and ultimately your health!
Oh, by the way, did you also know that calories from different food sources are burnt differently? We’ll talk about this and the various factors which affect how we burn calories in part 2 of this post. Stay tuned!