‘Fasted cardio’ is one of those buzz terms that you hear thrown around the health and fitness circuit, but are there any advantages to working out on an empty stomach? In this post, we are going to explore the benefits and downsides of spinning before breakfast, as well as why working out on a morning can be a life hack for getting fit.
‘Fasted cardio’ simply refers to doing cardio exercise (like spinning) on an empty stomach. For most people, this will mean working out first thing in the morning, but the same state could be achieved by intermittent fasting. Given that food is vital for energy, why would you do an energy-intense workout without anything in your belly? The answer lies in how our bodies store and use energy.
When we eat our blood sugar levels go up and our bodies use this as their preferred source of energy. We maintain glycogen stores, which are essentially converted glucose and carbohydrates, for a while after eating. By working out on an empty stomach, the body will not have sufficient glycogen stores to fuel itself and so will turn to stored fat. Part of the logic of fasted cardio is that it forces the body to tap into its fat reserves.
Now, you might ask whether fasted cardio, as compared to eating and then working out, will make any difference to your overall caloric expenditure that day (assuming you eat as normal in both scenarios). The answer is yes – but not significantly so. Stored fat is less efficient for the body to use because it has to convert into a usable energy source and that process requires energy. However, it does not need so much as to make a discernible difference between a fasted and a fed cardio workout.
So, if the caloric benefits are marginal, are there any other reasons to get on your spin bike before brekkie? There is some evidence to suggest that fasted cardio increases endurance levels and physical ability. However, there has also been research that shows the exact opposite effect! What does this mean for you?
When results like this happen in science, it can mean one of two things: either some of the scientists are wrong or there is no universal answer. In this case, we think it is the latter. We know people who swear by fasted spinning and could never imagine getting on the bike with anything in their belly, others have tried it and filed it under ‘never again’.
The way to find out which of these two types you are is to try fasted spinning for yourself. There is nothing inherently dangerous about exercising without food in your system, a 10-12 hour overnight fast is nowhere near enough to put your body into crisis mode. However, you may find that fasted spinning is more difficult, so if your body does not respond in a positive way know that you are perfectly safe. Needless to say, if you feel lightheaded or unwell, come off your bike immediately.
When to spin
Given that fasted spinning is really a matter of personal preference, is there a particular time of day that you should be working out? Again, the answer is whatever suits your lifestyle and your body. We often recommend spinning on a morning – not for any physical benefits, but because you are more likely to get your workout in if you get it done early. A commonly reported problem by people who work 9-5 is that they cannot muster the enthusiasm to spin after work.
If spinning on a morning suits your schedule but fasted spinning does not suit your body, eat something light but satiating prior to getting on the bike. A banana, a spoon of peanut butter, a handful of homemade granola, anything that will give your body a bit of fuel to power your spin session without sloshing around in your stomach. Be sure to avoid acidic drinks like coffee or juice, and aim for at least a 15-minute gap between eating and getting on the bike, then do your usual warm-up before jostling yourself too much.
Most people find that spinning on a morning fires them up for the day, rather than tires them out. If you are flagging after your morning spin workout, the culprit might be insufficient sleep or not eating enough (of the right foods!) post-workout.
Try it for yourself
The question of whether a fasted spin or a fed spin is better, as well as whether a morning spin or an evening one is better, is one of personal preference. We recommend that you experiment with food and workout timings to find the combination that suits you.