Do you still believe in counting calories?

Because of decades of misinformation, many people who want to lose body fat mistakenly believe that success hinges solely on the concept of calories consumed versus calories burned. Numerous self-proclaimed experts, e.g., doctors, nurses, dieticians, nutritionists, trainers, coaches, and especially the media, promote the idea that a calorie from protein is equal to a calorie from fat, which is also equal to a calorie from sugar. They suggest that cutting down on calorie intake is all you need to do to lose body fat. However, this notion implies that our body's physiological processes for converting food into energy, known as metabolism, are the same for all types of food. This is a simplistic, unscientific, and untenable view.

Let’s clarify some basic facts. All macronutrients including fats, carbohydrates, and proteins contain energy, which is expressed in calories. While we typically associate calories with food, they apply to anything; for instance, a gallon of gasoline contains approximately 31,000,000 calories.

A calorie, as measured in a calorimeter, is defined as the amount of heat required to raise 1 kilogram of water by 1 degree Celsius at sea level. The principle behind a calorimeter adheres to the law of conservation of energy: energy can neither be created nor destroyed. In an insulated system like a calorimeter, the heat energy lost by the hot object is equal to the heat energy gained by the cold object. For example, an Angus Burger Deluxe from McDonald's contains 750 calories. If we were to burn this burger, it would yield energy equivalent to 750 calories—enough to raise the temperature of 750 kilograms of water by 1 degree Celsius.

The term "calorie" is a shorthand for "kilocalorie," which reflects simplified calculations. A kilocalorie contains 1,000 calories, meaning that the Angus Burger with bacon and cheddar contains 750,000 calories. Don’t get overly concerned; this simplified math also applies to exercise calorie charts. For instance, if a piece of cardio equipment indicates that you burned 200 calories, it reflects 200,000 calories in the more precise sense. However, be cautious and don’t overly rely on exercise equipment calorie charts, as they tend to be grossly inaccurate.

This inaccuracy is due to several factors, primarily genetics. The rate at which individuals burn calories varies greatly and cannot be accurately measured using a typical cardio machine. A person’s caloric burn can be influenced by their size, hormone levels, lean body mass percentage, and body fat percentage. For example, a person who weighs 220 pounds and has 10% body fat burns significantly more calories than someone who also weighs 220 pounds but has 25% body fat. If both individuals used the same piece of cardio equipment at the same intensity for the same duration, they would receive the same “calories burned” reading at the end of their session. This discrepancy illustrates the problem: muscle mass is a key driver of metabolism. The more muscle one has, the more calories are burned, a factor that the simplistic calorie theory fails to consider.

Calories are measured using a device known as a “calorimeter.” The term calorimeter is derived from the Latin words "calor," meaning “heat,” and "metron," meaning “measure.” A calorimeter is simply an instrument used to measure heat. There are various types of calorimeters, and a bomb calorimeter allows for accurate measurement of the energy produced by food. In this device, a small vacuum of water is positioned above the food sample. Once the food is completely burned, the temperature of the water is measured. The increase in temperature indicates the amount of calories released. As noted earlier, a calorie is defined as the amount of heat needed to raise the temperature of 1 kilogram of water by 1 degree Celsius at sea level.

A machine cannot determine what happens inside the human body. While a calorimeter can measure the total amount of energy in a serving of Fruit Loops, it cannot account for the energy that the body does not absorb (which is eliminated) or the energy expended during digestion and assimilation. Furthermore, it does not reflect an individual’s efficiency in using food as energy versus storing it as fat.

As a person’s body fat percentage increases, their efficiency in burning food for fuel tends to decrease. In other words, individuals with a higher body fat percentage are more likely to store food as body fat. This is due to a linear relationship between higher body fat percentages and insulin insensitivity, which leads to a considerable release of insulin following food consumption. Carbohydrates are the macronutrient primarily responsible for these large surges in insulin, making them particularly problematic for anyone, especially those who are overweight and trying to lose body fat.

To understand why carbohydrates can be a significant hurdle when trying to lose weight, it’s important to grasp the role of insulin. This understanding reveals further shortcomings of the calorie theory when it comes to weight control.

Insulin is often referred to as the fat storage hormone. In simple terms, the higher a person's insulin levels, the more food they consume is stored as fat. When carbohydrates are eaten, the body breaks them down into a simpler, more absorbable sugar known as glucose. This glucose is then transported into the bloodstream. As blood glucose levels rise, the pancreas is signaled to release insulin. Insulin is responsible for processing glucose. Without insulin—like in the case of type I diabetes—glucose levels will increase dramatically and not be stored as bodyfat. This is referred to as internal starvation. No matter how many calories consumed, a type I diabetic will not gain weight. Eventually, if not treated, they will die.

Glucose is processed by insulin in two key ways. As glucose levels increase, insulin converts some of it into glycogen, which is stored in muscle cells and the liver. However, once these storage areas reach capacity—something that can happen quickly, especially if you don’t exercise—insulin will convert the excess glucose into triglycerides, which are stored as adipose tissue, or fat. Essentially, insulin promotes fat storage (called lipogenesis) and inhibits the breakdown of fat for energy (known as lipolysis). Even low levels of circulating insulin can prevent fat from being broken down and used as energy. Therefore, insulin is often referred to as the fat storage hormone.

As one begins to understand basic physiology and how calorie intake from food is managed, it becomes clear that losing weight involves more than just a simple balance of calories consumed versus calories burned. Tracking exactly what fuel your body is burning compared to what you're consuming is nearly impossible.

So, does counting calories matter or is it even necessary for weight loss? The answer is no. Is it at least better than nothing? Again, no. Counting calories is utterly inaccurate and a waste of time. Consider the poor long-term success rates of diets focused on food quantities rather than food types. Our bodies do not process food like a calorimeter. The idea that macronutrients are processed the same way by every individual is simply misguided. It’s even more erroneous to think that a calorie from sugar is processed the same as a calorie from protein or fat, yet this is a fundamental assumption of the calorie theory.