Fasted Cardio - Does it work?

The Benefits of Fasted Cardio – Does it Work?

Everyone who works out has different preferences. Some love challenging compound leg workouts, while others find any excuse to stick to the upper body. Some people can think of nothing better than getting up before the sun rises to pound the pavement for six kilometers, while others could not imagine working out any time other than the evening.

Like those examples, fasted cardio splits its advocates and detractors right down the middle. Those who believe in it and its benefits swear by them as a shortcut to fat loss and increased muscle definition, while others complain of a total lack of workout effectiveness. So which tribe is right?

What is Fasted Cardio?

For those who haven't heard of the trend, fasted cardio is the act of performing aerobically demanding exercise without having eaten anything beforehand. That means that any running, cycling or rowing activity qualifies, provided your heart rate gets above 70% of its maximum for an extended period.

According to medical experts and dieticians, to get to a properly "fasted" state, the body needs not to have consumed any food or non-water drink for at least eight hours, though some push that window out as far as 12 hours. For practical purposes, the most effective time to actually do exercise in a fasted state is first thing in the morning, as an evening run in a fasted state would require you to eat breakfast then get through most of your day without eating anything else.

The Benefits

The reason that fasted cardio exercise as a training protocol got some traction in recent years was due to two scientific studies that claimed some fairly eye-catching benefits. Researchers at a university in the United Kingdom ran a study on 12 volunteers where half exercised in the morning on an empty stomach, while the other half exercised after eating breakfast.

The six participants who did their cardio on an empty stomach knocked the breakfast eaters out of the park when it came to measuring fat loss. They lost about 20% more fat on average. In sports science, an effect of 5%-6% is considered significant, so 20% was a big deal.

Another study two years later by a team in the United States found another interesting benefit. It turned out that the study group that exercised without breakfast ate a significant amount less (again, around 20%) calories than those who ate before they exercised. The study measured this by examining all food eaten in the 24-hour period after the exercise took place. The results appear to suggest that there might be some link between exercising on an empty stomach and a reduction in appetite in the day after the exercise takes place.

So the summary of the two studies is that fasted cardio may help you burn more fat while you're doing it, while also decreasing the likelihood that you'll eat more calories the day after. When it comes to losing a few extra kilograms after a plateau or cutting a few extra percentage points of body fat, those sorts of differences matter.

The Drawbacks

Of course, no exercise recommendation is complete without a nod to the drawbacks. The effectiveness of fasted cardio is largely down to personal preference. For example, if you are someone who struggles with energy levels on an empty stomach, or feels nauseous if you exercise without eating first, then fasted cardio is unlikely to be a good option. That's because the main factor in getting the benefits is your ability to exercise hard enough to burn the fat in the first place. If you are struggling to perform due to tiredness or light-headedness, then you won't get to the point where you get any benefit.

If you are aiming to hit some new fitness goals this year, weighing up different options for your training can seem exhausting. Sign up today to Max's Challenge to start receiving the support you will need to succeed with our proven programs and goal setting.