Shape Up Fitness & Wellness Consulting Nutrition advice

To eat or not to eat before cardiovascular training

Though cardiovascular training has been challenged as the optimum way to lose body fat, it is still a viable way of increasing your caloric output when done in moderation.

In the fitness industry it has been quite common to tell people to do some cardiovascular training before consuming any food. The reasoning behind it is that fat oxidation should be  utilized more when exercising in a fasted state.

A recent study tested this theory on healthy young women. Now, media and bloggers like me have a tendency to generalize those outcomes and I want to be really careful to avoid this:

The researchers found no difference in fat loss among both groups (fasted and unfasted) but showed that both groups lost body fat with a calorie restricted diet.

This is where the problems start to show up. Just left at this we could come to the conclusion that training while fasted has no benefit. But, the sample of women was pretty small and the study was only done over the course of four weeks. It is very well possible that there would have been differences at a later point in time. In addition the dietary habits were self-reported and inaccuracy and misreporting could have led to changes in the outcome.

There is simply not enough evidence to rule out that doing cardiovascular training while fasted might lead to more fat loss than exercising while fed.

Either way, working out while on a calorie restricted diet will lead to fat loss.

What about HIIT?

This particular study only addressed steady state cardiovascular training. High intensity interval training is a completely different animal. Even though EPOC (excessive post exercise oxygen consumption) seems to be lower with HIIT than originally expected, there might be hormonal changes and changes in appetite that lead to an increased fat loss. Again, more research is needed.

What to take home:

The quality of training is just as important as the time you eat. If you don’t stomach food well before working out, then you might be better off exercising while being fasted. If on the other hand you die half-way into your workout then it might be time to grab a carb+protein drink and kick some butt.

There is rarely a “fit one, fit all approach”. For most people it is a trial and error thing. Some general suggestions can be made, but even those need to be individually adapted. Just because it works for you, does not mean it works for your buddy.

Have a great day,


Resources: Running on empty: can we chase the fat away? – Body composition changes associated with fasted versus non-fasted aerobic exercise

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