Fasted cardio myth debunked by science

Maybe it is time bodybuilders start training like cyclists

Fasted Cardio Myth Debunked

By Clint Latham – www.BikeALatteCO.com 

 I Wipe the sleep from my eyes, fumbling blindly in my closet for my bibs and ask myself time and time again; “Why am I doing this? Why am I doing this?”

I would slowly make my way downstairs while carrying my bike; just thinking that this won't even last an hour, as I try to find some way to grip any bit of motivation left from the depths of my soul.

I’m sure that you’ve heard it a million times; especially if you are involved in the body building community.

If you want to maximize fat loss, you need to wake up early and hit the cardio before a single calorie hits the pit of your stomach. But the science would actually indicate otherwise. If you lived during the late 1990’s you have likely heard of the health craze sweeping the nation: Body for Life.

It was a health and fitness challenge put on by sports supplement company guru Bill Phillips. I was especially fascinated by this challenge as it was based out of my home town of Golden, CO.

  In Bill’s chapter on cardio he had two basic principles:
1) Hit the cardio early before eating your 1st meal
2) Perform short, high intensity interval cardio or High Intensity Interval Training

The idea was that the body had been fasting all night while you slept; reducing blood sugar levels, decreasing muscle glycogen stores and further decreasing insulin levels. Thus if you hit the cardio before your first meal the body would have no choice but to use fat as its primary fuel source.

This would send the body's fat burning potential into high gear. Ever sense countless cyclists, bodybuilders and anyone else has been looking to cut weight; they have been clawing their way, tired and hungry, through high intensity cardio in the hopes of shedding a few extra pounds.

As I traveled the country to the world's biggest bodybuilding events - The NY Pro, the Arnold and the Olympia - I would hear this time and time again. You've got to do your cardio fasted if you want to burn fat. It is as if it had been inscribed into the 10 commandments.

As I would head down to the hotel gym in the morning for a spin, I would see countless bodybuilders knuckling the cardio equipment in the hopes of shedding a few extra ounces of fat, being so tired and hungry that they could barely keep a steady pace, let alone reach the intensities required for High Intensity Interval Training.

Could this really be the best way to burn fat? They looked absolutely miserable. As I started to get back into the racing scene, a friend and training partner (Gareth Thomas - the national triathlon coach for the UK) used to always harp on me before our rides. "How many grams of carbs have you eaten?"

But I always brushed him off. Here I was working with some of the fittest people on the planet, who can get to 3% & 4% body fat and your telling me to eat!? Yeah right!

But that's when I got curious. We have bodybuilders performing fasted cardio and we have cyclists cramming as many carbs as possible. Yet both are extremely lean.

What's the truth? How does the body oxidize fat?

The human body does not operate within a vacuum

The body is constantly adjusting its use of fat or carbohydrate usage depending upon a variety of factors. Kent Hansen, in his study, The Effects of Exercise on the Storage and Oxidation of Dietary Fat, found that, "Generally if you burn more carbohydrates during your workout you will burn more fat post workout".

While research does show that fasted cardio can increase the mobilization of fat from the adipose tissue, this only occurs at very low levels of intensity. In the study Regulation of plasma fatty acid oxidation during low- and high- intensity exercise, "Our data suggests that, in addition to sub-optimal FFA availability, fatty acid oxidation is likely limited during high-intensity exercise because of direct inhibition of long-chain fatty acid entry into mitochondria." 

If a bodybuilder performs HIIT, they may see an increase in fat mobilization but that does not mean an increase in fat oxidation. This results in all those fatty acids being re-packaged and stored back into the adipose tissue.

After all of that suffering you put it right back where it came from! Furthermore Jeffery F Horowitz in his article in the American Journal of Physiology, found that; “When trained subjects exercised at 50% of the their maximum heart rate, an intensity that equates a slow walk, there was no difference in the amount of fat burned - regardless of whether the subjects had eaten or not.”

These results continued to be the same until the subjects, that were fasted, exceeded the 90 minute mark. Only then did the fasted cardio begin to show favorable results. Thus what are we left with?

The body will burn more fat cells when fasted at a lower intensity, but the duration has to be longer than 90 minutes. Anything shorter and it's a wash. And if we try to increase the intensity, there is an inhibition of fatty acids being able to enter the mitochondria.  

Why bodybuilders should think like an endurance athlete

As a competitive cyclist my goal for each workout was to make my engine bigger, stronger & faster. The way to do this is to increase the size and density of your mitochondria. Mitochondria are what produce ATP and is the only place in the cell where fat can be oxidized. It is the cell's fat-burning furnace.

The more mitochondria my body has, the bigger my engine and the faster I can ride. Think about it like a car. If you have a V12 and a 4 cylinder engine both sitting at idle, which one is going to use more gas? The V12, right!

Thus we would be better suited to turn our bodies into a V12 mitochondria machine so that we are constantly burning more fat cells. The study: An acute bout of high-intensity interval training increases the nuclear abundance of PGC-1α and activates mitochondrial biogenesis in human skeletal muscle found that low volume, high intensity interval training increases mitochondrial biogenesis.

Within 24 hours of maximal intensity exercise, new mitochondria were being formed.

I preach to any new cyclist I that work with to always eat before their rides. Why? Because without the fuel to fuel your muscles, you can't reach the intensity levels required to produce the enzymes that lead to mitochondria growth.

I know countless bodybuilders who will preach, “You got to eat before you lift bro! You need to fuel those muscles.” Why doesn't the same principle apply to high intensity cardio? You need to fuel the muscles to perform at a high level in order to induce growth. In this case, increase mitochondrial growth and fat burning potential is the goal.

In the same study, they found that a combination of both endurance and resistance exercise causes a significantly higher degree of mitochondrial biogenesis then endurance exercise alone. Bodybuilders have the resistance training part down, but what about the endurance?

Most bodybuilders I know cannot wait for their cardio sessions to be over. In fact, most of them dread cardio. Enter the popularity of the high intensity interval training workout. It's short and sweet. We also know that one of the best ways to cut fat is calories in vs calories out.

As bodybuilders get closer to show prep they begin cutting calories drastically to start leaning out.

Now it is even more important that our mitochondrial engine is huge. We want to run the fat tank on empty.

When performing an HIIT workout at the correct intensities, the body uses roughly 75% carbohydrate and 25% fat.

 The body, fully stocked full of glycogen stores, has roughly 90 mins worth of fuel for a moderately intense workout. In order to maintain optimal levels of glycogen, a daily carbohydrate intake of approximately 3 to 5 grams per pound of lean body mass is recommended when accumulating between 1 to 5 hours of training daily.

If a bodybuilder cuts (and especially limits) their carbohydrate intake, they are already running on empty before they hit the gym.

The bodybuilder's worst nightmare

Muscle tissue is made up mostly of protein which, in turn, is made up of amino acids. Normally, your body does not use protein to produce energy. If you run out of glycogen stores and no glucose is available, however, your body will then break down its own muscle tissue to release amino acids.

These amino acids are sent to your liver where they are converted into glucose in a process called gluconeogenesis.

When your body starts to use muscle tissue for energy, you lose muscle mass.

Starving without any glycogen left in the muscles to fuel their cardio efforts, bodybuilders still hit the treadmill in the hopes of shedding more fat.

What's really going to happen is your body? It's now going to use the protein in that hard earned muscle to fuel your HIIT session.

Think about a Tour De France rider. (If you're asking what the TDF is, it's like the super bowl of bike racing) Why are they so dang skinny? They burn so many calories during the race that they cannot eat enough to restore glycogen stores.

What happens? The body starts eating the muscle. A bodybuilder is doing the same thing to a lesser degree during the cutting phase. The question becomes, why not have 20-40 grams of carbohydrates pre-cardio, to be able to hit the intensity requirements needed to build more mitochondria and save that precious muscle mass?

You will be a constant fat burning machine and not have to sacrifice any muscle mass! In my Ride to 75 programs for new cyclists, one of the key principles is fuel.

We want to ride to lose weight. Cycling for Weight loss requires that we build a big mitochondrial engine to be a 24/7 fat burning machine. Now it is never a good idea to make a major change before a big show.

However, you can start focusing on building your engine between shows by fueling your HIIT workouts which will burn more fat cells.

You will also have to suffer less during the cutting phase. If you or someone you know who is interested in achieving happiness and health on two wheels please share with them, Cycling for Weight Loss, the FREE resource guide is found here.

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