by John Hobbs

Created on: January 27, 2009   Last Updated: January 29, 2009

In terms of losing weight there are many different opinions which argue for and against the effectiveness of cardiovascular exercise before breakfast. Firstly, those who argue for it suggest, that exercising in the morning is the most effective time to do so as upon waking up our metabolisms have slowed down tremendously as a result of sleep. Furthermore, cardiovascular exercise will raise the metabolism allowing the body to burn more calories throughout the day, thus making it more efficient.

Other arguments for exercise before breakfast include the fact that our energy stores (glycogen) are at their lowest during and after sleep (before eating) as we are not getting any glycogen (from carbohydrates) to replace them. Theoretically, if we exercise before breakfast we will not be burning our energy stores but instead directly burning our fat stores instead. Furthermore, it would seem that this method would promote more effective weight loss.

However, there are contradictions to these ideas as studies have shown that muscle may be the secondary energy source and not fat stores. The implications of this would mean that cardiovascular exercise before breakfast may actually be detrimental health wise as well as not having any great benefit on burning fat. At the very least, by exercising before breakfast you will be burning some muscle as well as any fat stores and so it may not be the healthiest thing to do. Additionally, studies have concluded that breakfast in itself speeds up the body's metabolism by taking the body out of starvation mode' (excess calories before sleep are converted into fat stores to prevent the body starving without access to food for long periods of time).

Moreover, it could be argued that cardiovascular exercise may be more effective when done in the evening where the metabolism is at its lowest. Exercising at this point would prevent the body converting macronutrients such as proteins, carbohydrates and fats into fat stores (before sleep) and raising the metabolism to increase the body's efficiency in using them effectively. However, this may increase fat stored during sleep by promoting starvation mode.

Ultimately, there is no way to be sure whether there are benefits to whatever time of day you choose to do cardiovascular exercise in terms of burning fat as conflicting studies provide evidence for and against. However, it may prove healthier to avoid working out on empty stomach as you may be burning muscle more so than fat stores. Finally, a good diet is the most important aspect of a healthy lifestyle.

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