Calories, What are they and can we control them?

Calories, What are they and can we control them?

The concept of calories is not as easy to grasp as is having a concrete understanding of what, for example, a meter or a liter is - we can't see a calorie. Evolving attempts to clarify what it means to say “there are 80 calories in an egg,”1 or “I burn 320 calories when I run 5K,” continue to fall short. Considering “I need to eat four eggs so that I can run this 5K,” while less abstract, is not practical or even accurate. This is one of the many reasons that the idea of “balancing” calories or “counting” calories continue to fail for those attempting to manage weight.

What are Calories?

Calories (often abbreviated cal) are measurable units of energy. Scientifically speaking, one calorie is the amount of energy that is needed to raise one gram of water by one degree Celsius.2 How does that translate into day-to-day living? The body needs energy in order to function – to power the work of the heart and lungs, to maintain a normal temperature and to perform other bodily processes. Additional energy is needed for digestion, and for any other activities we do, such as exercise. During digestion, the body converts the energy from food (calories) into energy that can be used to function.

Let's reconsider our 80 calorie egg. When the egg is consumed, a small percentage of that 80 calories is used for the process of digesting the egg. The calories remaining after digestion are either used right away to provide energy for work, or are stored in the body for later use.

Calorie Requirements
The number of calories needed by the body varies from person to person. All else equal, men require more calories than women, a marathon runner will need more calories than someone of the same age, sex, weight and height who is sedentary, and an adolescent needs more calories than an elderly man.

The following terms may facilitate an understanding of how the body uses calories:

  • Basic Metabolic Rate (BMR) – the energy required for the body to stay alive. The BMR is measured when the body is at rest, at a comfortable temperature and there is no active digestion. The BMR is calculated based on a formula that accounts for the variables of height, weight, sex and age.
  • Dietary Induced Thermogenesis (DIT) – the energy required for digestion – to process the food through the body and store it. The DIT is energy required by an individual in addition to the BMR.
  • Total Energy Expenditure (TEE) – the total amount of energy required by the BMR, DIT and any additional activity.3

It is possible, but not practical, to calculate individual BMR, DIT and TEE. To determine BMR, DIT and TEE, nutritional authorities have defined “average” values. The USDA (United States Department of Agriculture) has published a table detailing the average needs of individuals according to age, sex, and level of physical activity. Accordingly, men from puberty through age 40 need 2400-3200 calories per day to maintain weight. Women of the same age require 1800-2400 calories per day. With increasing age, caloric requirements decrease. This is true for men as well as women.4

During childhood a person needs more calories to provide the energy and building blocks required for growth. Women who are pregnant need an average of 325 additional calories per day, with that energy need concentrated at the end of pregnancy.5 During lactation, an additional 400 calories per day may be needed to provide for adequate milk production.6 Caloric need may also be affected by some medications, illnesses and abnormally high or low thyroid hormone levels.

Does Input Equal Output?

In a perfect world, weight loss would simply be a matter of counting calories and adjusting the energy consumed to be less than the energy expended according to TEE – in other words, more calories would be burned with activity than would be consumed eating. The reverse would be true for the purpose of weight gain. When the amount of energy consumed is more or less equal to the energy expended, weight would remain stable. It is commonly believed, and not entirely untrue, that consuming too few calories can lead to malnutrition, and consuming too many calories can lead to obesity. However, not all calories, and not all foods, are created equally.

Calorie Density

Calorie density refers to the number of calories per weight or volume of food. Small portions of calorie dense foods are high in calories, whereas larger portions of foods that are low in calorie density have fewer calories. This means that some foods have more calories than others, even if the portion sizes are the same. Foods high in fat and/or sugar are generally considered to be calorie dense. Complex carbohydrates and proteins are lower in calorie density.

Foods lower in calorie density (especially vegetables) also tend to be more nutritious than calorie dense foods (bacon, for example). Foods lower in calorie density also trigger mechanisms in the body that signal satiety (the feeling of being full) sooner than do calorie-dense foods. Satiety is the body's way of signally that eating should stop. Many have learned to ignore the satiety signal and continue to eat long past when they become full.

Our relationships with food are more complex than feeling hungry or feeling full. Our eating habits (what, when and how much or little we eat) are also controlled by our emotions, the availability of the foods we like, our grocery budgets, and even our sleep patterns.

With increasing numbers of obese individuals in the world, weight loss is a hot topic – and a multi-billion dollar industry.7 Weight loss methods come and go, and few focus on maintaining a healthy weight once excess weight is lost. Weight management is a lifestyle, not a fad. Some supplements can enhance efforts to obtain and maintain a healthy weight.


Capsaicins are biologically active components of red pepper, also known as Capsicum annuum. Several studies have demonstrated that capsaicins can help with weight loss and weight management. Capsaicins increase energy, reduce appetite, and therefore reduce consumption of excess calories.8 Capsaicins also enhance the metabolism of fat. Capsaicin is not a “once and done” remedy. It is most effective for weight management when it is consumed in small to moderate amounts on a daily, or near daily, basis.9 Taking capsaicin will not result in immediate weight loss. It is best considered an adjunct to other weight management and lifestyle modification efforts.

Green Tea

The active ingredients for weight loss in green tea (Camellia sinensis) are the thylakoids. Thylakoids suppress hunger, resulting in lower calorie intake. People who drink green tea tend to be less hungry, become satisfied sooner, and crave sweets and salty snacks less often. By resetting the satiety signal, thylakoids reduce the chance of overeating. There is no standardized or recommended therapeutic dose of thylakoids for weight loss; drinking caffeinated green tea 1-3 times daily seems reasonable.10


Psyllium, or Plantano ovata, is full of fiber. Fiber has been found to have a positive effect on the intestinal microbiome - the bacteria in our intestines that help to maintain intestinal health and function. The bulkiness of fiber enhances the feeling of fullness, which a can help prevent overeating. In this way, psyllium can be helpful in weight loss and maintenance.11

Capsicum, green tea and psyllium have proven to be good tools for weight loss and weight management. As adjuncts to lifestyle modification, they can decrease hunger, thereby preventing overeating, reducing the ingestion of excess calories, and enhancing weight management efforts.


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3. Digestion, Absorption, & Nutritional Principles. In Barrett KE, Barman SM, Boitano S, Brooks HL, eds. Ganong's Review of Medical Physiology 25e New York, NY: McGraw-Hill; Accessed April 6, 2017.





8. Whiting S, Derbyshire EJ, Tiwari, B (2014). Could capsaicinoids help to support weight management? A Systematic Review and meta-analysis of energy intake data. Appetite, 73, 183-8.

9. Whiting S, Derbyshire EJ, Tiwari, B (2012). Capsaicinoids and capsinoids. A potential role for weight management? A systematic review of the evidence. Appetite, 59, 341-348.

10. Erlanson-Albertsson, C, Albertsson, Per-Ake (2015). The Use of Green Leaf Membranes to Promote Appetite Control, Suppress Hedonic Hunger and Loose Body Weight. Plant Foods for Human Nutrition, 70.

11. Mullin, G (2015). Supplements for Weight Loss: Hype or Help for Obesity: Part III. Nutrition in Clinical Practice, 30, 446-449.


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