Does Fasted Cardio Help with Fat Loss?
The bro science department is split down the middle on a controversial topic in the gym: is fasted cardio the best way to burn fat?
Ask two people at the gym, and you’ll likely get two different answers.
Proponents of fasted cardio argue that if you workout on an empty stomach, your blood sugar and glycogen levels are already low. This causes a drop in insulin levels which makes the body turn to fat for fuel.
Those who argue against fasted cardio use the same reason: your blood sugar and glycogen levels are low, which causes the body to go into a catabolic state and munch on muscles for fuel.
And there is definitely science to back up…you guessed, it—both sides.
So which is it? Does fasted cardio help or hurt fat loss?
We found the most recent studies to help answer that.
Studies on Fasted Cardio
It’s been about three years since the most recent study was conducted. Maybe the guys in the white lab coats are tired of trying to solve bro science debates. Or….maybe its job security?
Either way, the most recent study from 2014 contained 20 healthy young females over 4 weeks. The Fasted group performed exercises after an overnight fast of around 10 hours and consumed a meal replacement shake immediately post-exercise. The Fed group trained after a meal replacement shake. They exercised for 1 hour, 3 days per week. They were also provided with a diet plan to produce caloric deficits on both sides.
The outcome was that no significant changes were discovered in weight loss, fat mass, or other measurement, showing that no body composition changes occurred with fasted cardio compared to fed cardio.
Verdict: Fasted Cardio Does Not Produce a Greater Fat Loss Than Fed Cardio
In another study conducted just three years before the one above came to a different conclusion. Studying the effects of fasted cardio on metabolism and body composition, subjects both fasted and fed performed cardio for 60-90 minutes 4 days per week for 6 weeks. After 6 weeks, the fed group increased body mass by about 3 pounds, but no increases were seen in the fasted cardio group.
Additional tests showed lower body fat noted in the abdominal and leg regions in both groups.
In another study conducted a year before showed if you have a diet high in fat, fasted cardio will facilitate adaptations in muscle and improve glucose tolerance and insulin sensitivity.
The logic behind why this works with those on a high fat diet is because the link between a high fat diet and insulin resistance is strong. Fat accumulation inside muscle cells is linked to insulin resistance. Eating a high-fat diet creates an imbalance between fat storage and oxidation in muscle cells, which increases fat in cells.
Fasted cardio stimulates energy production via fat oxidation which helps balance the imbalance and as a result, increases insulin sensitivity.
Consumption of carbs prior to working out impairs the body’s ability to oxidize muscle fat cells and transport fatty acids.
Therefore, this study concluded that fasted cardio by people with excessive fat intake could help alleviate diet-induced diabetes.
This study showed oxygen consumption was higher after fed cardio versus fasted cardio and concluded cardio after a light meal is a better option.
So…do you feel like you’re at the squat rack refereeing the bro-science debate? So does science, obviously.
Should You Do Fasted Cardio
So what’s the result? Should you do fasted cardio or not?
Well, let’s get real—no one enjoys cardio unless they’re a masochist. You should do it when you WILL do it. If waking up and getting it out of the way helps you get it done—then do it.
If eating helps you get energized, or doing it after dinner helps, then by God, do it in the evening. Just do it.
Don’t get wrapped up in the info wars the fitness industry has created. If you really look into it—nearly every claim is both supported and debunked by science.
So do what is right for you—as long as you’re doing it—you’re winning. Win faster with muscle building BCAAs here. There’s no science that says amino acids are a lie. So get to it and get gains.