How Fasted Cardio Can Help Burn “Stubborn” Fat Faster
If you’re a woman, your hips, thighs, and butt are probably the last to really tighten up when you’re losing weight.
If you’re a guy, it’s almost certainly your lower abs, love handles, and lower back.
This isn’t a genetic curse—it’s simply a physiological mechanism your body uses to defend against extremely low body fat levels. And fasted cardio can help you overcome it.
Let’s start with a physiological explanation of the stubborn fat phenomenon.
Your body uses chemicals known as “catecholamines” to trigger fat burning. Catecholamines travel through your blood and “attach” to receptors on fat cells, which then trigger the release of the energy stored within the cells for use.
Fat cells have two types of receptors for catecholamines, however: alpha- and beta-receptors. To keep this simple, beta-receptors speed up fat mobilization, whereas alpha receptors hinder it.
The more alpha-receptors a fat cell has, the more “resistant” it is to being mobilized by catecholamines. On the other hand, the more beta-receptors a fat cell has, the more “receptive” it is to the fat-mobilizing molecules.
As you’ve probably guessed, the areas that get lean quickly have a lot of fat cells with more beta-receptors than alpha, and the areas that don’t have a large amount of fat cells with more alpha-receptors than beta.
Another problem with these stubborn fat deposits relates to blood flow.
You may have noticed that fat in areas like the lower back and thighs are slightly colder to the touch than fat in other areas of your body like the arms or chest. This is simply because there’s less blood flowing through the areas.
Less blood flow = fewer catecholamines reach the stubborn fat cells = even slower fat loss.
So we have a double-whammy of fat loss hindrance here: large amounts of fat cells that don’t respond well to catecholamines and reduced blood flow that keeps the catecholamines away.
This is why you can lose fat and weight steadily with almost all of the fat seeming to come from parts of your body that are already fairly lean.
For example, if you’re a guy it’s common for your chest, forearms, and calves to keep getting leaner and leaner, while your lower abs, love handles, and lower back refuse to budge. If you’re a woman, it’s common for your legs, abs, and arms to get leaner while your butt, hips, and thighs remain damn near unchanged.
Thus, once you get relatively lean, the more “stubborn” fat you can lose, the bigger the impact on your physique. Losing just a pound or two of fat from the “right places” does a lot more in the mirror than several pounds from areas of your body that are already lean.
How does fasted cardio help with this, you’re wondering?
Well, blood flow in the abdominal region is increased when you’re in a fasted state, which means the catecholamines can reach this stubborn fat easier, resulting in greater stubborn fat mobilization.
This means that while fasted cardio won’t help you lose more total fat every day, it will help you lose more of the fat you want to lose most.
And especially if you combine it with the right supplements, which includes two in particular I want to draw special attention to: yohimbine and synephrine.
Fasted Cardio and Yohimbine
Yohimbine is a supplement made from the Pausinystalia yohimbe plant, and severalstudies have shown that it can speed up fat loss.
It does this by stimulating the production of catecholamines, which speeds up your basal metabolic rate and suppresses your appetite.
A good example yohimbine’s effectiveness comes from a study conducted by scientists at the Université Paul Sabatier in France.
The researchers had six young men report to the lab and undergo both of the following protocols with one week between each:
- Consume 0.2 mg of yohimbine per kilogram of body weight after an overnight fast.
- Consume 0.2 mg of yohimbine per kilogram of body weight after eating breakfast.
As you can see in the graph below, blood levels of free fatty acids doubled when they took yohimbine after an overnight fast, yet remained unchanged when they took yohimbine after eating breakfast.
(I don’t want to wander off into the weeds here, but free fatty acid [FFA] levels are a reliable indicator of how much body fat is being broken down for burning, also known as fat mobilization.)
The same scientists also carried out another experiment on eight more men in the same study. In this case, they had everyone undergo all three of the following protocols with one week between each:
- 0.2 mg of yohimbine per kilogram of body weight without exercise.
- Placebo with 30 minutes of moderate intensity indoor cycling.
- 0.2 mg of yohimbine per kilogram of body weight with the same exercise protocol.
They found that both yohimbine and exercise alone increased fat mobilization 50 to 100% above baseline, respectively. When people combined both exercise and yohimbine, though, the effects were additive, and fat mobilization increased over 150%.
Here’s what the results looked like:
Yohimbine’s fat-burning effects go further than that, however: it can also help your body better “tap into” and burn stubborn fat stores.
It accomplishes this by attaching itself to and more or less deactivating the alpha receptors on fat cells, which, we recall, are the ones that gobble up catecholamines and shut down fat mobilization.
Thus, if enough alpha receptors are out of commission, it will be easier for catecholamines in your blood bind to the beta receptors on fat cells instead, which stimulate fat loss.
In other words, yohimbine prevents your fat cells’ alpha receptors from preventing fat loss.
Furthermore, remember which fat deposits are generally highest in alpha receptors? That’s right, the “hard-to-lose” bits that we want to eliminate most, which is why yohimbine is considered particularly effective for burning away stubborn fat holdouts.
I’m using “considered” advisedly there because while conclusive studies on yohimbine and stubborn fat in particular haven’t been done yet, we do have strong indirect evidence for our case.
For instance, in a study conducted by scientists at the Institute of Sports Medicine in Serbia, 20 elite level soccer (“football” to you non-’Muricans) players into two groups:
- Group one consumed 20 mg worth of yohimbine pills every day (0.25 mg/kg of body weight).
- Group two consumed an equal number of placebo pills that looked identical to the yohimbine.
The scientists had both groups follow their normal soccer training and a new strength training plan, and after three weeks, the yohimbine group lost five pounds of fat, whereas the placebo group didn’t lose any.
That’s impressive, but here’s the kicker:
These athletes started around 9% body fat, which means much of the fat they had left to lose was the stubborn stuff in their lower torso. Thus, a fair amount of the rather large amount of fat they lost was assuredly belly fat because it’s very unlikely any of these guys had pounds of intramuscular fat stores to burn.
All this is why I believe that yohimbine makes fasted cardio more effective than fed cardio for the purposes of losing fat, and losing stubborn fat in particular.
Now, a counter argument could be that as neat as yohimbine is, your body will simply compensate even more by burning even less fat throughout the day, resulting in more or less the same 24-hour fat loss as with fed cardio.
A fair argument, but I don’t think it’s the case.
Based on years of experience with my own body and working with tens of thousands of people through my websites, I’m fairly convinced at this point that yohimbine and fasted training does indeed speed up fat loss in a meaningful way.
Fasted Cardio and Synephrine
Synephrine is a naturally occurring substance that’s particularly abundant in the bitter orange fruit, which is why it’s often referred to by that name.
It’s chemically similar to the ephedrine and pseudoephedrine found in many over-the-counter cold/allergy medications and weight loss and energy supplements that contain ma huang.
Accordingly, synephrine impacts the central nervous system and increases basal metabolic rate, which accounts for up to 70% of your daily calorie expenditure, and also increases the thermic effect of food, which is the energy cost of digesting and processing what you eat.
There’s also evidence that synephrine blocks the alpha receptors on fat cells, which means that it can speed up stubborn fat loss in a manner similar to yohimbine, which is why I particularly like it combined with fasted cardio.