As gasoline fuels cars, calories fuel our bodies. A calorie measures the energy in the food we eat. Today, it seems everyone is counting calories.
The human body requires a minimum amount of premium fuel (good calories) to keep the engines of its organs running smoothly. That is to say, the interactions of foods and digestion provide the vital energy needed by the heart, kidneys, lungs and other systems to function well.
While at rest, lying in bed and doing nothing, the average adult requires a minimum of approximately 1400 calories per day. This minimum number of calories needed by the body while at rest is labeled as the Basal Metabolic Rate (BMR). It describes the essential energy needs of the body not under voluntary control. Blood pressure, body temperature and heart rate are examples of involuntary functions of the body.
Total energy intake is the amount of calories we consume in 24 hours and it varies from individual to individual. We require another 600 calories, in addition to the 1400 calories of the BMR, in order to move around and perform our daily tasks. Note these numbers are generalities.
We use the following sources to meet basic (and additional) calorie needs.
- Carbohydrates
- Fats
- Protein
- Vitamins
- Minerals
- Water
Total energy expenditure is the number of calories the body burns in a 24 hour period. It is determined by three factors.
- BMR burns 60-75 % of the calories we take in each day
- Physical Activity 10-30%
- Thermal effect of food burns 10-30 %.
It’s the number of calories used up to absorb, digest, transport and store food.
If you’re like most people, you have a hard time losing weight. You might say, “It’s in my genes, “Everybody in my family is overweight.” Or, ‘I love to eat.” Or, “I don’t like to exercise.” Or, “I have no will power.”
Although the above might be true, conventional thought tells us, most often, we gain weight when we consume more calories than our body burns off. Others strongly disagree with this notion emphasizing a calorie is not a calorie. Also, they report
processed foods and ingesting an overabundance of sugary drinks in our diet, rich in fructose, are the real villains in weight gain.
The average adult needs about 2000 calories per day to function well but several factors influence a person’s 24 hour total calorie requirements.
Total Calories are influenced by:
- Age
- BMR
- Physical activity
- Gender
- Muscle Mass
- Nutritional type
- Voluntary movement
- Medications
- Kinds of foods we consume
Young children require more calories than older adults. Men have more lean muscle mass and higher BMR than women. Every ten years, after the age of 30, physically inactive people can lose 3 to 5%% of their muscle mass as part of the aging process (sarcopenia). To prevent such a loss, physical activity and a strength training program act as good medicine…
Physical activity promotes increase in muscle tone and weight stability. If we enjoy doing a particular exercise, there’s a greater chance of it being a long lasting part of our healthy lifestyle. Nutritional type influences how we digest food. Voluntary movements help. Why not answer the telephone standing up or routinely getting up from the computer or the sofa every 20 minutes and stretch? I’m sure you have many more and better ideas. Medications can interfere with metabolic pathways.
Lastly, not all calories are created equal. The kinds of foods we put into our body and how we metabolize them differ from one person to the next. As noted, our body’s metabolism converts the calories in the food we eat into the energy needed to power the things we do from thinking to sprinting.
Our knowledge about nutrition, diet, food and physical activity is an on-going education. It behooves us to place nutritious fuels into our bodies. Are there exceptions? Sure. But we benefit when the exception does not become common place.
Glossary
Basal Metabolic Rate (BMR) is also referred to as the Resting Metabolic Rate (RMR)
Thermogenesis is the thermal effect of food causing the body to use calories to absorb, digest, transport, and store food.
One definition, a calorie (from the Latin calor meaning heat) measures the amount of heat needed to raise the temperature of one gram of water one degree Celsius. Others refer to it as the food calorie, amount of heat needed to raise a kilogram of water one degree Celsius.
Sarcopenia is the loss of muscle tissue as part of the aging process.
Wilbur O. Atwater, the 19th century scientist, is credited with the chemical analysis of foods and calorie counts in the U.S.
References
Beecher GR; Legacy of Wilbur O. Atwater: Human Research Expansion at the USDA; J Nutr Jan 1, 2009
Dietary Guidelines for Americans; Us Department of Agriculture; 2010
Mahan, Ik, and Stump, SE; Krause’s Food, Nutrition and Diet Therapy, 2007 Haehling Stephan et al; From Muscle Wasting to Sarcopenia and Myopenia; J. Cachexia; Dec 3, 2012
This article is intended solely as a learning experience. Please consult your physician for diagnostic and treatment options.