I am going to be upfront with you; I will not be providing a best exercise for weight loss. I do not believe there is such a thing. But we can succeed in weight loss, if we stay committed to ourselves over time. It is my intent, over a series of articles, to give you the knowledge that will help you succeed in this undertaking. In part 1 of this article, I am going to address some of the physiology that will help give you a clearer understanding of the relationship between Kcals and our bodies. Part 2 will tie the physiology into diet & exercise, and part 3 will provide you with exercise and lifestyle strategies for positively changing your body composition.

#1 –  The Classic Over-Squeeze
I am going to use a car analogy to describe how our bodies make use of the calories we put in, and calories we burn off. Let’s pretend our car has a full tank of gas. We drive to the gym, burning 10 litres of gas in the process. After the gym, we plan on putting 10 litres of gas back in the tank, to bring us back to a full tank of gas. However, we pump a little too much, and we end up with gas everywhere because the tank cannot adapt to the additional fuel.

The same is true for our bodies. If we burn off the same number of Kcals that we consume, our “tank”, or weight, will stay the same. However, if we put in more energy than we burn, we hold the additional energy in storage sites, or fat cells. This creates a net gain in weight. One pound of fat contains 3500 Kcals of energy. To make this tangible, there are 140 Kcals in a can of Coke. If every day, we drank one can of Coke above our “gas tank” capacity, we would gain 1 pound every 25 days.

Evn though I used a sugar-loaded soft drink as an example, this holds true for all foods. One Kcal from Coke is the same as one Kcal from brocolli (we’re talking energy here, not nutrition). Regardless of whether the energy starts as a carbohydrate, protein, fat, or alcohol; all excess Kcals are stored as potential energy in the form of fat. Some days we underfill our tank, some days we overfill our tank. What makes the difference over time is which one we do more often.

Key Point: To lose weight, you need a sustained net energy loss. All foods contribute to filling our tanks with fuel, but if not burned, the excess is stored as fat. Our next point addresses energy out.

#2 – Idling Gas Guzzlers
Gas in your car is burnt both while driving, and while idling. We often think of driving as being the only culprit for emptying our gas tank, but imagine if we could never turn our cars off. Idling 24 hours a day, 7 days a week. This in effect, is our resting metabolism. Surprisingly, we “idle” away  70-85% of our daily energy expenditure (this includes food digestion, and resting metabolism requirements of our cells). “Driving”, or physical activity, accounts for the remaining 15-30%. Physical activity directly and indirectly increases our metabolism, taking advantage of our “idling” Kcal expenditure. Some forms of exercise are more efficient than others for increasing metabolism, which will be addressed in part 2 & 3 of this article.

Key Point: The majority of our daily energy expenditure comes from normal cell metabolism, while a minority comes from physical activity. This fact emphasizes the importance of metabolism when trying to lose or gain weight.

So far, we’ve looked at how calories in and calories out affect our body weight over time. Keep in mind, that our bodies are much more complex than the simplified comparison to automobiles used in this article. Stay tuned for part 2, where we’ll explore how we use energy in exercise, and how our diet can speed up or slow down our progress.

-Stuart