One of the common approaches to weight gain or weight loss is the caloric formula, which is the belief that simply subtracting calories burned from calories eaten gives you your net gain or loss. This formula, while an important tool, is woefully oversimplified, and when used alone it can really lead to poor results, whatever your goals might be.
"Calories Eaten - Calories Burned = Gain or Loss"
Before really digging into whether the formula is accurate, I feel it’s important to first point out that it is misleading. Many people believe that calories=weight, which they don’t. Calories are a measurement of energy, i.e. a particular nutrient contains a certain amount of energy per gram. And, different nutrients have different energy capacities. When folks wrongfully interpret calories as a measurement of weight, they tend to avoid all calories indiscriminately, rather than understand that calories are not created equally. 500 calories of broccoli have a different impact on your body than 500 calories worth of French fries. In the same vein, certain types of calories affect certain people differently. If I eat 500 calories of rice, and someone else eats the same 500 calories of rice, our bodies respond differently to those calories. In short, calories are not equal, and are not a measurement of weight.
Now let’s take a look at the “calories eaten” side of this equation. As mentioned above, calories are not created equally, and neither are people’s responses to similar calories. Beyond what’s noted above, eating fewer calories doesn’t always lead to weight loss. The body is going to look for an equilibrium, meaning it is going to adjust to what it’s given. For many, decreasing caloric intake might lead to one, or both, of two options:
1 - The body begins storing more food as fat in a desperate attempt to hold onto as much energy as possible. Since it’s getting fewer calories, it’s going to try to store energy.
2 - The body begins to feel sluggish as it tries to restrict energy output. Since the body is getting less energy, it’s going to try to expend less energy. For those looking to lose weight, this problem now compounds on itself, since less energy to use means less effective workouts or activities, and less tolerance of activity before release excess cortisol (more on that below).
Simply looking at calories eaten as a complete portion of the caloric equation is a severely shortsighted and ineffective approach. Calories are not the same, don’t affect people the same, and the body doesn’t respond to a decrease in calories as a stimulus to simply drop weight.
On the flip side, calories burned is also an incomplete picture. If I tell you that I burned 1,000 calories during my workout, you actually know very little about the ultimate outcome of that workout. Take, for instance, a marathon runner vs a powerlifter. They both might burn 1,000 calories during a training session, but the effect of that workout is very different. In one case, the burn was nearly entirely aerobic, depleting the muscle completely. In the other case, the work was completely anaerobic, meaning explosive strength/power based, tearing the muscle and setting it up to grow. The end result of that 1,000 calories worth of work is very different in each case. One might deplete both fat and muscle, while the other builds muscle and burns fat.
From another standpoint, the idea that more calories burned equals weight loss can lead many towards overtraining. If someone thinks the equation simply needs more calories burned, they can easily put themselves in a position where they over-train and release cortisol (a stress hormone), which causes increased blood pressure, fatigue, disrupted sleep, moodiness, and weight gain.
Ultimately, the caloric formula is a tool that can be used to illustrate some overarching principles, but it really is not a comprehensive picture. It is not enough to count calories if your goals are to gain muscle or lose weight. I could go on for a few more pages on this, but in an attempt to be succinct, I’ll just say that calories are not equal, on the eaten or burned side of the equation. Planning for nutrition and training regimens have to take into account the quality of the diet and the effect of the workout, beyond their total caloric value.