Cardio, Calories, and the Starvation Response

Most of the time, when someone decides that they want to lose fat, they inevitably head for the nearest fad diet. However, 95% (closer to 100%) of the time, these fad diets fail. The reason they fail is because exercise is rarely incorporated into the program. In order to lose fat, there must be a deficit of calories in the diet. In other words, your body must use more calories than you eat in order to use its fat stores for energy. This seems simple enough; however, it becomes a bit more complicated. There are two ways a calorie deficit can be accomplished. The first one is to eat fewer calories. The second one is to use more calories (exercise). The best way to accomplish fat loss without hitting a plateau and failing is a combination of both. You must eat less calories and burn more calories. If you try to accomplish a calorie deficit only by eating less calories, then you're body thinks it's starving, and will go into a "starvation mode" where it lowers its metabolism in order to prepare for a period of little food (this is more than likely a protective response from years ago when food actually did become scarce, unlike today). Another reason that the metabolism is lowered is because when there is a period of little food, your body tries its best to protect the brain. The brain always requires glucose (carbohydrates that are in the body) to run; however, glucose can not be stored in the body. Therefore, the only way for the body to get glucose is to eat its own muscle (muscle can be converted to glucose) - which lowers your metabolism and causes the starvation response. So, the body accomplishes two things by eating its own muscle: it provides glucose for the brain and causes your body to require less food, since less muscle equals a lower metabolism. When the starvation response is elicited, you smack into the fat loss plateau and the fad diet fails.

When you incorporate exercise into your routine, your body feels more comfortable with not lowering your metabolism. If you are exercising frequently, then your body thinks, "I'm actually doing something, so there is probably an abundance of food now, and I shouldn't worry too much." Therefore, the starvation response is mostly avoided. Two important forms of exercise to produce this affect are weight training and aerobic exercise (cardio). However, this article is mostly about cardio.

The goal of cardio is to burn calories while avoiding the starvation response. Many times when you mention "exercise" or "cardio", people immediately get negative thoughts in their head about the extreme difficulty of doing such exercise, but these thoughts are misguided. Cardio gets easier as your body adapts, is very rewarding, and can even be fun.

How Cardio Becomes Easier While Still Burning the Same Amount of Calories

As you do cardio more and more, you body begins to adapt and become better at performing the same work, but with less perceived effort. The body becomes able to move nutrients and oxygen around faster because you build new capillaries, the cells produce more mitochondria (the powerhouse of the cell), your heart becomes more powerful, your body produces more blood, and a host of other adaptations that would cover a whole textbook. The main thing to note here is that you still burn the same amount of calories, even after your body adapts and cardio becomes easier. However, with your new, more adapted body, you will be able to accomplish exercise that burns even more calories resulting in even more fat loss. For instance, in order to burn 300 calories, you would have to walk for about 1 hour and 45 minutes. In contrast, jogging for about 25-30 minutes (the amount of time will vary depending upon your speed) will burn 300 calories. Obviously, the last one is more practical unless you just have a huge amount of time on your hands. Walking also doesn't elicit the endorphin high that running/jogging does either (discussed later).

The Overload Principle

When you begin a cardio program, your first goal should probably be to adapt to the point where you can burn a sufficient amount of calories. This involves the overload principle. The overload principle is simple: in order to initiate adaptations within your body you must exercise with either a greater intensity, duration, or frequency. Depending upon the type you decide to overload (intensity, duration, or frequency), you will adapt to that type. For instance, if you want to run faster in the same amount of distance, you should run faster, and your body will adapt to that. If you want to run farther, you should run farther, and your body will adapt to that. There is a high degree of specificy that goals along with this principle, but that is the topic for another article. Pretty much, the overload principle reveals that doing the same routine every time without trying to push yourself harder will result in no adaptations. For instance, if you do the same aerobics tape everyday, then your body will never adapt any further - since there is no need for it to. However, if you were to get a more advanced tape and do it, this would initiate an adaptation in your body, but then you would have to find an even harder tape to initiate any further adaptations. Keep in mind though, if you decide to stay at the same level of fitness and do the same routine, then you will still burn the same amount of calories, and if your goal is just fat loss this may be a potential option for you.

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