A Question On Cardio!

I recently answered this question from one of my clients and I thought it would be worth sharing…

Is this true? Does training first thing in the morning on an empty stomach burn a lot more fat? I have read that 20 minutes cardio on empty burns the same amount of fat as 60 minutes at any other time of the day.

I think this is fitness fiction at its best (as you know I am always a sceptic!!!)

I do think there is a possibility you will burn more fat if you do cardiovascular exercise first thing in the morning on an empty stomach, as your body has a vastly reduced amount of glucose (sugar) present in the blood and the muscles to fuel the activity, and will therefore look to fat as a primary source of fuel. However, it is not necessarily as simple as that…

I think exercising without having eaten within a few hours before is dangerous as it puts you at a substantially higher risk of passing out (due to low blood sugar) which neither makes you look lean or cool!

Furthermore, there is strong evidence to suggest that when your blood sugar gets low people will gorge themselves on food to satisfy their hunger. They will eat significantly more after a period of starvation than if they maintain a better blood sugar balance. For example you may have experienced it yourself when you are hungry you are more likely to pick up a energy dense nutrient deficient food such as a chocolate or a biscuit than knock up a tuna sandwich as you intuitively know the sweet thing will knock the edge off the hunger instantly.

Another thing to also bear in mind is that when your body can’t get the glucose from food it releases a hormone called Cortisol that will break down muscle for fuel. As you know a lb of muscle burns 50 calories per day at rest which means that if you wish to be trim and lean you need muscle and obviously if your body is using it for fuel your ability to burn calories is greatly reduced. Hence the reason low calorie diets or starvation diets never work.

So in the long run (so to speak), doing cardiovascular exercising in the morning on an empty stomach will not really benefit you.