Even before intermittent fasting, some were already getting up at the crack of dawn to work out on an empty stomach! Those people were unknowingly practicing what is known now as fasted training. Fasted workouts are more than just working out in an empty stomach, it involves working out in a fasted state. This means your last meal was at least 12 hours prior to your workout so that your body is put into a fasted state in which it stops breaking down food and its glycogen stores are at its lowest. This gives fasted workouts the supposed fat burning benefits!
However, are fasted workouts really more effective at burning fat than working out in a fed state? Before you get up early in the morning, keep on reading to find out whether fasted workouts are as beneficial as everyone claims they are...
Do you burn more fat working out in a fasted state?
The main benefit, or arguement, that everyone touts when talking about fasted workouts (specifically about fasted cardio) is that it helps you burn more fat by helping your body tap into your fat stores for energy. Fasting causes insulin levels to drop and glycogen stores to deplete which allows body fat to be broken apart and burned as free fatty acids. Which has led to the theory is that fat is used as a fuel source instead of glucose. Although fasted workouts increases fat oxidation (fat burning), it doesn't translate to increased fat loss. What translates to actual fat loss and changing one's body composition is a long term balance over weeks – this is what will determine with your lose or gain fat. But, let's look at what the studies have to say...
In a small study conducted on two groups of healthy women, researches assigned one group to perform fasted cardio on an empty stomach, while the other group drank a 250 calorie pre-workout shake. Both groups were following the same guidelines of being in a 500 calorie deficit and performing one hour of steady state cardio 3x a week. The results showed both groups experienced weight loss and a reduction in body fat percentages with no significant differences between groups! Another study focused on those wanting to build muscle, followed a group of participants that followed an IF diet and an 8-week weight training workout plan, and a group that didn't. The study concluded that IF didn't improve muscle mass compared to the other group, but it also didn't make exercise less effective. On the other hand, one small study showed that fasted training has a positive affect on how quickly the body uses protein and carbs, opposed to those who have a carb-loaded breakfast before training. All-in-all, the results are limited and mixed, but if there's one that sums up the research on the topic is a meta-analysis that was published in 2017. The analysis consisted of five different studies that looked at fasted vs fed exercise, and concluded that working out fasted did not result in great weight loss or changes in lean muscle mass and fat mass.
There are several small studies done on fasted training for fat loss, however, there are still pretty limited and short-term. So, take these studies with a grain of salt. There is some evidence that prove fasted workouts have some potential benefits (even outside of burning fat), but at the end of the day, the most important thing for fat loss is your total calorie deficit and training consistently - be it high-intensity cardio, steady-state cardio, or lifting weights.
Potential benefits of fasted workouts
Although fasted workouts doesn't technically burn more fat than working out in a fed state, there are still some pretty good potential benefits of it that may sway you to skip your breakfast before you workout every once in a while!
- Better fat utilization – You may not burn more fat in a fasted state than in a fed one, but performing low-intensity aerobic exercise, like walking, is better done fasted than fed. Eating breakfast before performing low-intensity exercise blunts fat oxidation. So, if you like to do low to moderate intensity cardio in the morning, consider it doing fasted!
- Helps increase the growth hormone – Fasting is not only known for promoting weight loss, lifters also love it for it's muscle-building potential! The human growth hormone, or HGH, has a few awesome responsibilities in the body including helping make new muscle tissue and improving the way our bodies break down glucose without using oxygen. Fasting and exercise helps increase HGH which helps it run effectively and give you the benefits you're looking for. Increasing HGH can help with weight loss and muscle-building goals, however, the increased HGH effects typically end once the fast is completed. If you really want to maximize your weight loss and muscle-building efforts then implement a regular weight training routine, eat enough protein and carbohydrates, and fast regularly to keep your HGH levels up!
- Can help improve endurance – Several studies have linked fasted cardio to increasing one's VO2 max, this refers to your maximum oxygen usage during exercise. To put it simply, fasted cardio can increase your ability to take in oxygen and deliver it to your muscles, helping you work harder during your training session! If your main goal is fat loss, doing a morning fasted cardio session, especially a high-intensity workout like HIIT, can help improve your endurance and possibly even training performance!
Should you work out in a fasted state?
This new and trending fat loss technique is what it is, a trend. The research is limited and there is no long-term study to conclude that fasted workouts burn more fat than working out after eating breakfast. However, there are still potential benefits of working out fasted and honestly, there's no harm in doing so if you enjoy it! There are some people who claim they simply love how it feels working out fasted, so try it out for yourself, but make sure to approach it in a safe manner! Instead of having your 373 Lab Pre-Workout or BCAA's have a cup of black coffee for good energy, and make sure your meal the night before was filled with plenty of protein and good carbohydrates! This will ensure you have a safe and potentially great fasted workout, and don't forget to have a post-workout protein shake or protein and carb-rich meal right after!
Didn't enjoy it or felt like it wasn't for you?
Then work out at any time of day, enjoy a nutrient-dense meal or snack a few hours before your workout, and crush it! Whatever you decide to do, whether it's training fasted or fed, make sure to follow a good training program and make sure your prioritizing a nutrient-dense healthy diet – this is the best for those who want to lose weight or attain other fitness goals!