On one side some suggest that exercising on an empty stomach is more effective as it forces the body to use fat stores for fuel, resulting in a greater weight loss.
Conversely, others claim that exercising in a fasted state doesn’t offer any benefit and may even work against you. They point out that the body burns roughly the same amount of fat regardless of whether the stomach is full or empty; but, in addition, by exercising in a depleted state your body will also burn muscles for energy, not only fat.
So who’s right? Who’s wrong?
A newly published study has found that people can burn up to 20% more body fat by exercising in the morning on an empty stomach1. Have we finally reached an answer? Not so fast...
Researchers from Northumbria University in Newcastle in the UK, sought to find out whether the known benefits of exercising after an overnight fast were undermined by an increased appetite and eating more food later in the day.
They discovered that those who had exercised in the morning did not consume additional calories or experience increased appetite during the day to compensate for their earlier activity.
More importantly, they found that those who has exercised in a fasted state burned almost 20% more fat compared to those who had consumed breakfast before their workout.
They concluded that performing exercise on an empty stomach provided the most desirable outcomes for fat loss.
"Our results show that exercise does not increase your appetite, hunger or food consumption later in the day and to get the most out of your session it may be optimal to perform this after an overnight fast” one of the lead authors commented.
Similar outcomes were reached in another study conducted in October 2012 at Glasgow University in Scotland. Researchers found that people who exercise before breakfast used up 33% more fat than those who exercised after eating. They also registered a drop in the blood fats responsible for heart disease2.
Not everybody agrees
Other studies suggested opposite results. In particular, a report published in Strength and Conditioning Journal concluded that the body burns roughly the same amount of fat regardless of whether you eat before a workout3.
Moreover, a separate study published in 2002, found that healthy women who consumed 45 grams of carbohydrates before their workouts ended up eating less throughout the remainder of the day4.
So, what we can do about it? Shall we exercise in a fasted state or not?
First off, let’s stress out that the biggest difference is between doing something and being a couch potato.
But if you’re going to exercise, it seems that there is a slight advantage in doing it on an empty stomach.
Provided that: (i) you don’t compensate this by overeating later during the day and (ii) that you can actually workout on an empty stomach without feeling dizzy, drowsy or fainting.
If you need to much on a granola bar before a spinning class or have a slice of toast before your morning run, do it. What really matters is that you exercise.
If you can manage to do it in a fasted state consider it as the icing on the cake.
Just remember that weight loss is a slow process that entails a lot of discipline and patience.
As long as you keep at it results will show.
The Iron You