One of the more commonly used phrases when speaking about calories and nutrition is “a calorie is a calorie,” which, to be honest, we find a bit misleading. The term "calorie" is a measurement of energy; technically, it’s the amount of energy needed to raise one gram of water one degree Celsius.

How do calories work?

Over time, however, calories have come to be associated with human biology, not just with energy. From an actual energy standpoint, in a closed loop system, all calories are equal. But when we look at what happens to a calorie after we ingest it, then we start seeing some differences depending on the source of the calories.

Although all foods provide energy to the body, foods also provide nutrients, influence hunger, and trigger different hormonal pathways. Consider 100 calories from table sugar compared to 100 calories from olive oil: they have different speeds and pathways of digestion, trigger very different hormonal pathways, and can have very different impacts on weight management and overall health.

Nutrient density

So when considering calories, it is important to not just consider the total amount of energy, but also daily nutrient needs. Health-care providers often recommend that clients focus on nutrient quality, not just total quantity, an approach called nutrient density.

Nutrient density is a concept that promotes getting the most out of daily total calories as possible, and striving to meet not only energy needs but also vitamin, mineral, and other nutrient and biological needs within those total calories.

Calorie needs

Calorie needs vary from person to person, and a one-size-fits-one approach should be taken to best meet individual needs. Factors influencing energy needs include exercise, recovery, illness, and metabolism, all of which can impact an individual’s calorie prescription.

Careful attention to the nutrient density of daily calories can help identify gaps in nutrient intake, and in these cases, nutritional supplements can be used to complement the diet.

Exercise

Intensity and duration of exercise and training can also have a major role in total calorie needs. Many active individuals underestimate the added calories and added nutrients needed for their activity.

For many reasons, individuals respond differently to different mixes of calorie sources; therefore, for a more personal caloric prescription, consulting with a health-care practitioner is best.