How Does Fasted Cardio Work — Or Not Work?!?!
How does fasted cardio work?!?!
Oh, I take it that your friend, family member, coworker, stranger you follow on social media who you place more trust in than you fucking should, is probably doing fasted cardio and telling you about all the great results they’re getting.
So you’re probably thinking about doing fasted cardio because, fuck, if a shitload of people are doing something then it must be something you have to do too.
As we all know, a lot of people doing something means it has to be a good thing or else so many people wouldn’t be doing it. One such example is investing money with Bernie Madoff.
Talk about a sure thing!
Yup, it has to be good if everybody and their mom is doing it!
Is fasted cardio among the many, many things the masses have been right about?
Hmmmm…
If you couldn’t tell by its name, fasted cardio is cardio performed fasted.1A true fasted state is 8-12 hours after your last meal. This aspect of fasted cardio is something that many, many people get wrong, as they think skipping a snack or meal and then doing cardio qualifies as being in a fasted state. IT FUCKING DOESN’T!!! In most cases, that means doing cardio upon waking in the morning and before breaking the fast with breakfast.2Yes, folks, that’s where the word “breakfast” originates from. It’s a breaking of a long period without food, otherwise known as a fast. Yup, you just learned something new today!
Yes, that’s right.
Cardio is already horrible as it is, but fasted cardio calls for making it even more horrible by doing it on an empty stomach.
The thinking is that without enough glucose to use for energy because you’ve gone a couple of hours without food, your body has no other choice but to burn fat for fuel. This is opposed to eating and signaling the release of insulin, a hormone that not only transports glucose for immediate energy or stores it as fat for later use but also suppresses lipolysis, or the breakdown of fat.
Makes sense not to eat, right?
Right!
It turns out that fasted cardio burns fat, as it’s advertised as doing…3Uh oh! You see those ellipses? That means a big but is coming up, so brace yourself!
…but to a certain extent.
About 20 percent more fat is burned during a fasted cardio bout than one performed in a fed state.
Wait, isn’t that good news?!
Not really.
See, while fasted cardio burns more fat, it’s not exactly the kind of fat that matters.
The type of fat that all forms of exercise burn are intramuscular triglycerides (i.e. stored fat in the muscles), which have no impact on health or appearance. It’s this type of fat that fasted cardio burns with greater efficacy.
It’s the visceral and subcutaneous fat that we care about.4i.e. the fat making up your love handles and many, many, many other trouble spots. How you tap into those fat stores is by elevating the metabolic rate, or increasing the body’s energy expenditure. Fasted cardio fails to do this, as the calorie-burning effect takes place only DURING the bout but not AFTER.
Wanna know what helps burn fat when you’re not doing shit?
Yup, muscle!
It’s good to see that you’ve been paying attention and know about the benefits of weightlifting, but that’s not what I was going for.
The answer is high-intensity interval training (HIIT) and food.
Eating prior to a cardio session burns more fat in the 24-hour period following the workout because exercise increases the thermic effect of food (TEF), with the body using even more energy than normal to break down the food, a process which carries on for the rest of the day.
As for HIIT, the all-out bursts of activity produce lactic acid, which places a demand on the body for oxygen to eliminate the toxic substance that fatigues muscles. Then because so much oxygen is used during the workout in order to oxidize lactic acid to carbon dioxide and water, the body has to take in excess oxygen after the workout to return the body to its normal resting state. This excess post-exercise oxygen consumption (EPOC), as well as other recovery processes, requires energy and turns the body into a calorie-burning machine for hours on end.
So perform HIIT fasted!, you say.
Not so fast!!!5See what I did there?
While eating breakfast isn’t necessary for each and every person, a hypoglycemic state for most of the population will preclude them from having the energy to perform at a high enough intensity to reap the afterburn effects of EPOC.
For most people, cardio on an empty stomach will impair their ability to go hard, limiting the number of calories burned during the session and throughout the day as part of the post-exercise afterburn effect.
Additionally, because fat isn’t the only power source that your body turns to when glucose is scarce, the caloric cost of exercising without a meal is double the amount of muscle tissue, or protein, burned when in a fed state.
Performing fasted cardio at a high intensity only worsens this.
As I’m sure you know, cortisol is a stress hormone that triggers the release of amino acids, glucose, and fatty acids for energy. That’s one of its many functions. Its levels are at the highest in the morning because of the overnight hours spent without food, in addition to the role it plays in helping you wake up. As such, your body is in a catabolic state, meaning it’s primed to break down molecules for energy. Since glycogen isn’t available because you haven’t eaten in hours and the body would rather preserve its fat deposits for future emergencies, the prime candidate is muscle tissue for amino acids. Eating will prevent this catastrophe and lower cortisol levels. Not eating and then going balls-to-the-wall on the treadmill will only jack cortisol levels sky high.
What that means for you is that if you’re unable to bring your cortisol levels down, your body will spend most of the day in catabolism.6This is especially true if you’re pairing your cardio with a caloric deficit like someone with a brain would if they were after fat loss.
Yes, your body will spend most of the day eating away at that hard-earned muscle that you kinda sorta need to burn shitloads of calories at rest!
Now, I know what you’re thinking.
Like, how could I not?!?!
After all, I’m omniscient.
What you’re obviously thinking is that if fasted cardio has the potential to burn all-important muscle, then why do bodybuilders, bikini girls, and other physique competitors do it religiously?
My, that’s an easy question that can be answered with an even easier question: what do anabolic-androgenic drugs do?
Correct!
Anabolic-androgenic drugs place you in a constant state of anabolism, or muscle building, effectively blunting the effects of elevated cortisol and allowing users to preserve muscle as they tap into their fat stores.
People not on anabolic-androgenic drugs will lose WEIGHT by doing fasted cardio, but it’ll primarily be water and muscle — not FAT — as demonstrated. This won’t happen to people on drugs.
What I’m getting at is that the majority of bodybuilders, bikini girls, and other physique competitors who do fasted cardio with no ill effects are on drugs.
Sorry to ruin the fantasy for you!
When people get on a fitness kick, they often start out aggressively, doing things that impair fat loss.
You know, things like dropping their calories from maintenance to starvation, eliminating whole food groups like dietary fat and carbs, working out for hours and hours on end, popping every fat burning pill known to man.
Fasted cardio is another thing we can add to the list of shit that people do with the best of intentions.
Bless their hearts!
As we see, while almost everyone is doing fasted cardio, it’s truly a protocol for more, let’s say, “special” trainees.7If you can’t tell, “special” is a euphemism for enhanced.
If you’re not “special”, stay the fuck away from fasted cardio.8If you still can’t tell, “special” is a euphemism for being on steroids!
Don’t believe me, though?
Still think fasted cardio is the Holy Grail?
Then at least
• drink coffee or green tea (both without milk or sugar) before your workout for the energy needed to go at a high intensity,
• take a branched-chain amino acids (BCAAs) supplement as you work out to try and minimize protein breakdown, and
• eat a protein- and carb-rich meal IMMEDIATELY after.
Do at least those three things so you don’t come off being that “special”, and that’s in the other sense of the word!9If you can’t tell, “special” here is a euphemism for being mentally challenged!
NOTE: When performing cardio in a fed state, it doesn’t have to be in the form of a complete meal, especially if you don’t have the time to eat one, like early in the morning. An apple, banana, orange, something to that effect, can be consumed in minutes and provide the energy for you to power through your workout without the body having to turn to burning as much muscle were you to perform the cardio completely fasted. In other words, what you eat doesn’t have to be large. Just eat something!
Glossary: bodybuilder, caloric deficit, calories, cardio, dietary fat, exercise, fitness, hormones, intensity, muscle, results, supplement, treadmill, work out, workout