Why Cardiovascular Workouts Are Inefficient for Long Term Weight Loss
Many fitness experts have over the years promoted low-intensity cardiovascular exercises as the best methods of losing excess body weight. As fallout of this, the first thing most people think of when they want to start losing weight is which type of cardiovascular exercise they are to engage in.
There are actually several studies which have indicated that the lower the intensity of the exercise, the more the “percentage” of fat that will be used as fuel by the muscles. This is because when doing low-intensity cardiovascular exercises, the body is basically functioning in what is generally regarded as its “fat burning zone”. This is a state in which it usually burns more fat than when exercising at higher intensities.
When doing cardiovascular exercises, you are normally working within your “target heart rate zone” for fat burning – your fat burning zone. You normally get to this zone when you are exercising at about 60-70% of your maximum heart rate. When in the fat burning zone, the calories you will be burning will be in the following ratio: fats – 85%; carbohydrates – 10%; and proteins – 5%.
Given these fat burning capabilities of cardiovascular exercises and the stated ability of the body to burn more fat at low-intensity than at higher intensities, why then is there so much contention about the effectiveness of cardio exercises in helping people lose weight?
To truly understand why low-intensity cardio exercises are somewhat inefficient in assisting people achieve long-term weight loss success, you first need to know where the energy being used for the cardio exercises is coming from.
When exercising, for your muscles to functional optimally, they require energy which is usually gotten from protein, carbohydrates, and fats in your system with the latter two being the preferred choices. These energy sources are normally found in two major places in your body – your bloodstream and your muscles.
Carbohydrates, the primary source of energy for the body, exist in the bloodstream as glucose while they are found in the muscles as glycogen – a mixture of glucose and water. The muscles generally prefer to hold on to their internal stores of glycogen and release them only as a last resort.
Fats are however stored in the body tissues in the form of triglycerides. Fats generally need to go through oxidation – the burning of fat in the presence of oxygen – before they can be released into the bloodstream as energy fuel. Fats are also known to require more oxygen to burn than carbohydrates.
On the commencement of an exercise, the body goes into what is called a “fight or flight” mode – its automatic response to actual physical threats or any form of stress. Exercise is generally considered as a stressor to the body and once the body goes into this “fight or flight” mode, it secretes epinephrine and norepinephrine. These chemicals activate hormone-sensitive lipase (HSL) – a specialized enzyme involved in fat metabolism. This enzyme carries out a process called lipolysis whereby it breaks down the body’s fat stores for energy.
Due to the fact that low-intensity activities are not that difficult for the body to handle though it is stressed, the body uses the process of lipolysis to release fat stores from the body tissues into the bloodstream as energy fuel rather than use up the available glucose in the bloodstream.
Although, this process of lipolysis (burning of body fat) would seem the ideal way to go about losing extra body fat, it is nonetheless not that efficient due to the fact that it has what is called a “burn off” effect. This means that the fat burning effect of lipolysis stops almost immediately when you stop your cardiovascular exercise. This is the major limitation of cardiovascular exercises as the process of lipolysis only last while you are exercising and just a little more during your recovery phase.
As an illustration, for every mile an average man runs, he expends about 100 calories and most women even less. With about 3,500 calories in one pound of fat, the average person would therefore need to run about 35 to 45 miles or engage in about 6-10 hours of continuous activity to use up this energy. This somehow explains why so many people spend so much time in the gym but get very little results from their cardiovascular exercises.
Apart from the “burn off” effect, cardiovascular exercises may also cause lean muscle loss. It helps to remember here that the fat used for lipolysis came from your body tissues including muscle tissues in which they are stored as triglycerides and since they are used up during your low-intensity cardio exercises, your legs may burn and you may experience muscle soreness. This happens because the intensity of the exercise was not strong enough to trigger the body’s self-protective mechanisms which would have protected the muscles.
A loss in lean muscle usually leads to a reduced BMR which translates to a reduction in your overall metabolism. This is also partly why a lot of people might put on some weight even when they eat the same amount of food and continue engaging in low-intensity cardio exercises.
Therefore, while engaging in low-intensity cardio exercises allows you to lose a modest amount of body fat, you may actually end up losing some lean muscles in the process also. Retrospectively, low-intensity cardio exercises actually offer little benefits for all the hard work.
However, would it not be great to keep lipolysis – your fat burning process – running continuously for more than 24 hours after you stop exercising? Wouldn’t that be an incredible boost to your weight loss efforts? Actually, there is an exercise technique that does just that and it is called High Intensity Interval Training – HIIT for short. You really need to check it out!