Many people prefer exercising on an empty stomach as they feel like it burns more calories and helps with faster weight loss. As with many diet and exercise related questions, this does depend on a number of factors, but is there any truth to the idea?
A quick search of “fasted cardio” will reveal very mixed messages about whether it works or not, but in short it means exercising on a very empty stomach.
True fasting begins 8-12 hours after your last meal and this is why many people like to exercise in the morning before they eat any food. Research by the British Journal of Nutrition shows that people can burn up to 20% more body fat when exercising on an empty stomach. It also revealed that these people didn’t feel the need to snack more during the day to compensate for their earlier work.
Just as people lose weight at different rates, this works differently for everyone who tries fasted cardio and although your friend might lose the pounds quickly, you may struggle to shift them because of how your body works. Fasted cardio is safe to do, but you should try to keep the intensity fairly low in order to keep yourself from feeling light-headed and so that you have enough energy to put in a good performance. If you wanted to do a 60-minute run for example, it’s probably a better idea to eat beforehand so that you didn’t experience low energy levels, but a quick 20-minute workout could be beneficial for you after fasting.
For anyone that does exercise in a fasted state, it’s extremely important that you stock up on important nutrients afterwards. This is because the body uses up all the nutrients once exercise has finished, and so you will need to quickly consume carbohydrates and protein before you begin to feel out of energy. People that have been working out for a long time will be able to recognise their limits better than beginners, so try to be very aware if you’re just starting out and pay attention to what your body is saying.
The International Society of Sports recommends that 0.14-0.23 grams of protein is consumed per pound of bodyweight after exercising, which is around 20 grams for an average size woman.
There is a possibility that exercising in a fasted state could result in loss of muscle rather than loss in fat. This is because your body doesn’t really have any control of where it gets its energy from, and so it could break down muscle tissue for fuel. Jim White, exercise physiologist, says that this all depends on the type of exercise you do. He recommends sticking within 50-60% of your target heart rate if you want your body to use up excess fat – which means keeping the intensity fairly low.
In conclusion, whether you practice fasted cardio or not is completely up to you. Whilst some people see great benefits to their body and mind from doing so, others don’t function well first thing in the morning or when they feel hungry, and that’s absolutely fine! Remember to always listen to your body when you work out and recognise when you need to take a break or stop to avoid injury.