I have made a list of calorie claims, myths, truths, and partial-truths below to help my readers understand how to decipher what they see and read out in the world today.
1. Calories Fuel Our Bodies
The term "calorie" was first coined in the 19th century for steam engine heat conservation. Basically, a calorie is a unit of energy required for 1 gram of water to heat 1 degree Celsius. It was in 1890 that the USDA first brought this term over to the food industry. Scientists would literally take a piece of food and light it on fire to see how much it would heat water. Some of you may remember doing this in science class, I know I do. The term "calorie" in the food industry should actually be "kilocalorie" as the calorie count you see on food packaging refers to the amount of energy required to heat 1kg of water by 1 degree Celsius, but everyone usually drops the "kilo" because we are all lazy...
There is also one problem here, our bodies do not have little fires raging in our cells to produce energy, we break down macronutrients (proteins, fats, carbohydrates) to use their chemical energy. Also, instead of one enormous chemical plant, we have billions of little energy producers in our cells called mitochondria that are much more efficient. The problem that many people think and feel, is that all calories are created equal, when this simply is not the truth, which leads me to #2.
2. All Calories are Created Equal
When we eat stuff, i.e. food, the chemical makeup of that stuff must be broken down into smaller chunks to be absorbed, transported and utilized by our bodies. This is not a passive process which means that we need energy to digest, or in other words, we require energy to produce energy. (Takes money to make money right?) To assume that all calories are created equal is just silly.
Carbohydrates are the easiest macronurtient to digest and therefore has the highest yield. Carbs, also known as sugar, is nature's form of jet fuel for our bodies. The problem is, our society seems to pack more and more and more sugar into everything, leading us to the point where we would never come close to burning off as much of that energy as we take in, leading to adipose tissue (body fat)...but that is a different blog topic altogether. Anyways, carbs return about a 90-95% energy yield per calorie. What I mean by that is, for example, every 100 calories of carbs you take in, it requires 5-10 calories of energy to digest.
Fats actually have a slightly higher energy yield than carbohydrates, ranging in the ballpark of 95-96%, but this should not be alarming as our diets require much less fat than carbs. What this means is that in 100 calories of fat, it takes about 4-5 calories to digest.
Protein has the lowest energy yield, which can actually be very beneficial for weight loss. Only about 70-80% of protein calories consumed are returned to the body when digesting proteins which isn't all that surprising as the body greatly prefers fats and carbs for energy whereas protein is mostly used for tissue repair. Regardless, proteins are highly recommended throughout the day for those looking to lose weight or are highly active.
3. You Are What You Eat
We have all heard this term before, but don't think that everything you put in your mouth stays in your body and is digested. Just keep in mind, there are things that come out the other end - and that will be as far as I go with that! When you eat your food, your teeth chew it up, then the juices in your stomach breaks things down further into a paste. This paste then travels through your intestines where the nutrients are absorbed through the spongy walls. For most people, however, 5-10% of this paste just keeps passing on through and is expelled as waste.
For the most part, fat digests easily and passes through the walls quickly. Animal protein sources are absorbed better than plant-based sources. Then we come to carbs. Glucose and starcy carbs (i.e. chocolate, potatoes) are absorbed rapidly, whereas high-fiber carbs like in fruits, vegetables and grains take their sweet time passing through your system. Not only that, by fiber seems to prevent your body from absorbing certain calories and can even lower cholesterol levels. A certain size of broccoli and chocolate may register as the same number of calories in a laboratory, but that does not mean that they act the same way in your body. Studies have shown that individuals with high-fiber diets have close to 20% of their daily ingested calories move through their digestive system without being absorbed. Less calories this way can lead to less body fat!
4. "I'll Just Burn it off at the Gym"
Many people grossly over-estimate how many calories they actually burn during a workout. Everybody has heard someone say (while reaching for a second helping of dessert), "Oh, I'll just burn it off later when I am (insert weak excuse for an exercise here)." Truth is, even the craziest of fitness nuts only burn, at most, 30% of their daily calories in working out each day.
Most of our calories burned on a day to day basis come from doing things like digesting food, thinking, breathing, repairing a cut to your leg/face from shaving, etc. This is known as our resting metabolic rate, which means you are burning a ton of calories even when watching tv! There are other daily activities can also contribute to our daily caloric expenditure that are known as non-exercise thermo-genesis (N.E.A.T.) such as walking up the stairs, walking your dog, having sex, etc.
I know what you may be thinking, "Hell, I don't need to exercise then!" Keep in mind that exercise causes a whole list of benefits too long to list in this blog, so I highly recommend you continue (or start) to exercise 5-6 days a week. Not only that, but a properly designed strength and conditioning program consisting of cardio and resistance training will raise your resting metabolic rate, mentioned earlier, so that the rest of the day when you are not exercising, you will burn more calories than the average person!
The best scenario in this case would be to exercise often, but to also make small changes in your life that can result in bigger changes over the long-haul. For example, if you live or work in a multi-storey building, take the stairs more often rather than the elevator. Park at the back of the parking lot when shopping to force you to walk a bit further, etc.
5. "Big" People Have Slower Metabolisms
There are many studies that show that thin people may potentially absorb and burn dietary fats quicker than their "bigger" counterparts, but this topic is definitely false. When referring to the "resting metabolic rate" (RMR) discussed in #4, studies have shown that the average man requires 11 calories per pound of body weight for their RMR, even if they sat in front of the tv all day. If you do the math, you would quickly discover that the bigger you become, more calories are actually required to maintain your current weight.
6. Low Calorie Foods Help You Lose Weight
This seems to be a very hot-button issue as of late. Many people seem to think that eating "Low-Fat" or "Low-Calorie" food substitutes will help them lose weight. It looks and sounds good on paper! The problem here is that companies often remove fat from products, but replace with either sugar or artificial sweeteners or in high-sugary foods, they remove natural sugars and replace with zero-calorie artificial sweeteners. The problem arises when those "zero-cal" sweeteners hit the bloodstream. A long story short, the body thinks its taking in sugar (and calories) when in fact the artificial sweeteners are useless which causes a blood-sugar dip causing you to crave guess what, more sugar!
More and more studies are coming out detailing how individuals who frequently consume things like "Diet" sodas and low-cal foods are actually gaining weight in the process, oh, the irony! The ideal situation here would be to remove soda from the diet and replace with another zero-cal beverage...water!