Understanding Calories & How They Relate to Weight Loss
The word ‘calorie’ is a ubiquitous part of our dietary vocabulary yet are very much an abstract idea. You can’t see calories, touch them or sense them but unfortunately you can see their effects all too well if you eat too many of them. As omnipresent as calories are in our lives and in the minds of those determined to lose weight, they are perhaps the least understood aspect of nutrition for most dieters, which is ironic given the fact that an understanding of calories and their role is crucial to anyone serious about losing weight. The confusion over calories comes mostly thanks to the bombardment of contradictory information from food manufacturers, the weight loss industry and the media- which uses dietary information as a form of entertainment and not as a tool for educating the public. Both food manufacturers and the weight loss industry have a vested interest in telling us a lot about nothing- which leaves most people bewildered by what to do next in terms of their weight loss and open to believe just about anything and most importantly- buy more of their products. In today’s world an educated consumer wouldn’t be much of a consumer since an understanding of the science behind calories would make them unlikely candidates for popular diet/exercise trends, nor would they fall for the many calorie related strategies used by food manufacturers to get you to buy more of their products for the wrong reasons. (Read my article on the economics of obesity for more information on how marketing confuses consumers.) Calories aren’t rocket science, but they are a bit complicated. Nevertheless, if you take the time to understand this fundamental element of nutrition, it will help you go a long way in achieving your weight loss goals.
A Calorie Isn’t A Calorie- Understanding The Nomenclature
One of the most bewildering problems is the word itself as the word calorie as it appears on food labels isn’t exactly the correct term, even though it’s widely used. There is a saying that you can’t understand the nature of anything unless you call it by its proper name and I think this precept is applicable in this case as well. A calorie isn’t the correct label for the energy in our foods. A calorie (written with a lower case ‘c’) is a measurement of heat energy used in thermodynamics and is never used in regards to food energy measurement. The energy in our foods is measured in kilocalories,(k/cal), which means 1,000 calories with the word ‘Calorie’ (with a capital ‘C’) used by those in the dietary fields to refer to kilocalories. Are you confused yet? A medium sized apple therefore isn’t really 80 calories in the strictest sense, it’s 80 kilocalories or 80,000 calories! It makes sense to keep the numbers manageable by expressing all values in units of a thousand and I am more than certain that food manufacturers would be horrified to see their products labeled with three extra zeros added to the calorie count. Other countries avoid the whole conundrum by using the metric measurement of kilojoules, which is 4.18 kilocalories. From here on in for the sake of simplicity I will use the correct nomenclature- Calorie or kilocalorie when referring to units of food energy measurement so we are all on the same boat.
What Is A Calorie/Kilocalorie?
A kilocalorie is the amount of energy required to increase the temperature of one liter of water by one degree Centigrade from 14.5 degrees to 15.5 degrees Centigrade. A wonderful definition, but one that means little to anyone without a background in chemistry or an understanding of the metric system. To translate for those who didn’t grow up with meters and grams, a Calorie/kilocalorie is the amount of heat needed to raise a quart of water (which is just about a liter) by 33.8 degrees Fahrenheit – which is 1 degree Centigrade. Water boils at 212 degrees Fahrenheit (100 degrees Centigrade) so that medium sized apple we were talking about earlier has just enough energy to boil a quart of water. Let’s put this into perspective-Given that the average American adult male consumes a total of 2437 calories daily, that would be enough energy to boil a little over 6 gallons of water! The amount of energy is astounding, but it you must note that energy from foods is released very slowly through the processes of digestion and metabolism. If not we would have some serious problems to contend with and spontaneous combustion would be a fairly regular event! Where does all this energy go? Mostly towards the biological work required for our bodily functions- everything from breathing to using our muscles and repairing our cells. In essence this energy is used to maintain balance (homeostasis- a bigger word with the same meaning) with the heat energy released from these functions serving to maintain our body temperature. (See my article on metabolism here).
So how do we measure Calories/Kilocalories? The process actually isn’t that complicated as the food is burned to ash and the heat released is measured in a device called a bomb calorimeter. Since the Third Law Of Thermodynamics states that energy can be neither created or destroyed, we know that the amount of energy released from a food inside our body through digestion and oxidation would be about the same as the amount of energy released if it was completely burned in a closed system. A bomb calorimeter does just that and researchers make allowances for the components of food that would not be completely digested in your body. Some plant based fibers, for example cannot be completely digested and thus can’t be converted into energy. A a result any calories from indigestible food components are subtracted from the total amount of heat energy measured. Also subtracted are the nitrogen components of protein based foods which are also excreted by our bodies without being used. By taking these factors in to consideration researchers are able to arrive at a final figure that best represents what our body would actually gain from a food. Without these corrections you would find many low calorie foods like vegetables being listed as high calorie foods with a much higher Calorie/kilocalorie count than they really do. Thanks to the requirements of the provisions of the Nutrition Labeling and Education Act enacted in 1990, all foods in the U.S. have to have their nutritional information listed prominently on the container in which they are sold. These labels are often misleading in terms of their caloric counts as while the kilocalorie values are accurate, the serving sizes are kept ridiculously low so that the calorie count won’t appear to be too high. Take the label on a small bag of a brand of ‘natural’ potato chips for example with it’s serving size of 1 ounce which has a value of 150 kcal. Now 150 kilocalories may not sound like much, but that’s only one seventh of the total bag, and I can’t tell you the last time I saw anyone eat one seventh of a small bag of potato chips and walk away as most people would eat the whole bag. Thus the real energy yield is more like 1050 kcal which is almost half the average number of kilocalories needed by a woman to maintain her bodyweight and is a glaring example of a seriously high kilocalorie food masquerading as a harmless low calorie treat thanks to serving size manipulation.
The Caloric Components Of Carbohydrates, Proteins and Fats
Now the energy content of the food we eat come from three macronutrients- carbohydrates, protein and fats. Protein and carbohydrates for the most part have a total of 4 kilocalories per gram, (a gram is about one third of an ounce by the way), whereas fats have 9 kilocalories per gram. Consequently, foods that are high in fat are usually high in kilocalories. Olive oil is has many heart healthy benefits, but it is still very much a high calorie food. As little as two tablespoons have 28 grams of fat, which adds up to 248 kcal. Putting that into perspective- two tablespoons of olive oil are calorically equal to three medium sized apples, which is one reason why it’s so important to be aware of the fat content of your foods as the numbers add up pretty easily quickly. The mathematically savvy amongst you may have discerned that while olive oil has a total of 28 grams of fat- it has 248 kilocalories and not 252 kilocalories. If 1 gram of fat yields 9 kilocalories then it should have 252 kilocalories- (9X28=252) but it doesn’t. The reason for the discrepancy is that oils (and most foods) contain some amount of water which is calorically inert.
Why do carbohydrates and proteins have only 4 kilocalories per gram, whereas fats have 9 kilocalories per gram? The answer isn’t that hard to fathom if you keep in mind the basic elements and molecular make up of these nutrients. Protein is made of amino acids while carbohydrates is made up primarily of glucose. Fats are composed of fatty acids which are the most complex in terms of their biochemical structure and have the greatest number of chemical bonds holding it together. If you conceptualize the idea of energy being released when a food is broken down, it makes sense that fatty acids- which have far more bonds holding it together than glucose or amino acids would thus store more potential energy and be as a result much higher in kilocalories.
Calories/Kilocalories And Body Fat
One of the most important themes from the laws of thermodynamics is the idea that if we consume more Calories than we need our bodies will have no choice but to store them as body fat. This will happen regardless of how healthy the food source may have been. You can get fat from eating high protein foods, fats or carbohydrates- even if it is labeled fat free, organic or heart healthy. It makes no difference whatsoever the type of food you eat, if you ingest more than you should, you’ll gain weight. But as we said before, it is easier to go overboard calorie-wise from eating foods that are high in fat since they are so much more calorically dense. I should mention as well that at 7 kcal per gram, alcohol has more calories than protein and carbohydrates and the added curse of being processed in such a way that if you consume too much of it can significantly increase fat stores around your liver and other organs. (See my article on alcohol and weight loss as well as my post on visceral abdominal fat).
Weight Loss And Calories/Kilocalories- Why You Can’t Lose 10 lbs of Fat In A Week
One of the best aspects of understanding what calories are is that it gives you an informed perspective as to how ludicrous rapid weight loss plans can be. The Holy Grail of losing 10 pounds of fat in a week is highly improbable, given the concrete mathematics involved and even doing so in two weeks isn’t within the realm of rational expectations. Consider that a pound of fat contains a total of 3,500 kilocalories- and that the average male needs anywhere in the ballpark of 2000 to 3000 calories to maintain his bodyweight, (this figure is slightly lower for females). Thus to lose ten pounds of fat in a seven days you would need to eat 35,000 kilocalories less or burn off that many kilocalories through exercise. Even if you did both such a result is unlikely. With the figures in front of you it is clear to see that no diet can bring about a ten pound fat loss in a week. You would have to eat nothing at all and still increase your activity level to make it possible, and between us I don’t know anyone who can exercise effectively while starving. Weight loss is thus a gradual occurrence and a matter keeping your caloric intake within an acceptable level while increasing your body’s need for more energy. You can do this by exercising and increasing your muscle mass- since muscle requires additional calories to be maintained. None of this happens overnight so always be wary of anyone or anything saying otherwise, especially if it comes with a lightening of your wallet.
Calories Matter But What You Eat Matters More
You might think that since weight gain depends on calories from any source that you can eat pretty much anything as long as your intake remains within the boundaries of what you need to maintain an energy balance. This is the premise behind many diet fads and food manufacturers love it as it advocates that you can eat what you want- junk food included. As attractive as this may sound to the consumer however the logic behind it is severely flawed. Firstly, the energy balance principles derived from the laws of thermodynamics don’t account for the fact that we are human beings and that many other factors come into play where weight gain is concerned. If you follow the idea of weight gain being a matter solely based on energy balance then their should come a time when weight gain stops as the increased mass and consequent increase in metabolism compensates for the extra calories being consumed. The larger you get the more calories you burn and yet in the real world this almost never happens as people continue to gain weight throughout the course of their lives. Our behavior and eating patterns play a major part in weight gain and food manufacturers are quite aware of this. If you only ate junk food in amounts meeting your body’s energy requirements it might work, but those foods are engineered by folks who spend a lot of time, money and effort studying and mastering the creation of foods that are designed to make you eat more. Foods containing multiple ingredients that can be almost addictive. (Read my article- Can Foods Be Addictive here) Studies have found that ingredients in many processed foods such as high fructose corn syrup make us eat and drink far more than we should and thus contributing to the continued weight gain. The same applies to high fat foods and high sugar foods which activate our reward system in a way that makes us eat more and more- past what our body requires for energy balance. Combine that with the ease of consumption of liquid calories in sodas and juices and you have a situation where it is very difficult for moderation to occur. More importantly, by continued consumption of junk foods you simply can’t learn the healthy eating habits needed to keep weight off. Nor can you learn how to select single ingredient natural foods which are much easier to eat in moderation than than their distant multi-ingredient, processed cousins. Long term weight loss comes from a change in lifestyle and thus anything that keeps you away from doing so makes it far less likely that you’ll be successful in your long term weight loss endeavors. (See my article on Controlling Your Eating Habits.)
So what about the stories of those who lost significant amounts of weight in a short time from low carbohydrate diets? Again an understanding of the science behind how our body works gives us some insight. Carbohydrates are stored in our body as glycogen, which is a combination of glucose and water. When you reduce your carbohydrate intake your glycogen levels will drop and you will lose some of that water in the process. That’s the weight you’ll see lost on the scale but it is all water weight, and does nothing to reduce your fat stores. An effect that is at best temporary and a distraction from the practice of watching your portions and eating in a consistently better fashion with a diet that includes all food groups in sensible quantities. There aren’t any shortcuts and faced with the abundance of so many energy dense foods and our inability to accurately estimate how many calories we consume it is a difficult task indeed. A slight excess in caloric intake can go a long way as eating only 40 calories more than our daily energy requirements can add an extra 40lbs of fat over the course of ten years. Taking that into consideration and the fact that our ancestors burned off far more calories than we do today due to the rather active nature of staying alive in a world without supermarkets and shopping malls, and of course the superabundant food supply we have today, it becomes a bit easier to understand how our current obesity crisis came about. It might be an uphill battle, but it’s one that can be won with a consistent approach that emphasizes lifestyle change and not immediate weight loss results.
1. National Health & Nutrition Examination Survey- Intake of Calories and Selected Nutrients for the United States Population, 1999-2000
2. Kushner, Robert (2007). Treatment of the Obese Patient (Contemporary Endocrinology). Totowa, NJ: Humana Press. pp. 158. ISBN 1-59745-400-1. Retrieved April 5, 2009.
3. Wells JC, Siervo M. Obesity and energy balance: is the tail wagging the dog? Eur J Clin Nutr. 2011
4. Peter G. Kopelman, Ian D. Caterson, Michael J. Stock, William H. Dietz (2005). Clinical obesity in adults and children: In Adults and Children. Blackwell Publishing
5. Erlanson-Albertsson C. How palatable food disrupts appetite regulation. Basic & Clinical Pharmacology & Toxicology 2005
Kevin Richardson is an award winning fitness writer, one of the most sought after personal trainers in New York City and the creator of Naturally Intense High Intensity TrainingTM. If you live in the New York metropolitan area and need help losing weight or taking your body to the next level give Kevin and his team a call at 1-800-798-8420 or click here to get started with 50% off your trial personal training session.