Best Supplements For Fasted Cardio

Supplements for fasted cardio

In the early days of bodybuilding, fasted cardio was regarded as counterproductive, a sure way to lose muscle and not make any gains. Very few utilized it as a part of their training program, and research was scarce.

In recent years, however, fasted training in general has made a comeback and a ton of research has been conducted, identifying both the upsides and the downsides.

Luckily, there are some supplements which can both

  1. enhance the upsides
  2. negate much of the downsides

And that’s exactly what we’ll be discussing in this article.

By the end of this, you’ll know exactly what supplements you should be taking for fasted cardio and why.

So, if you’re ready to stop letting cardio kill your gains and instead use it to your advantage, read on…

What Is Fasted Cardio?

What is fasted cardio?

For those who aren’t familiar with the term fasted cardio, it simply refers to doing cardio style training when you haven’t eaten in several hours and your Insulin levels are at baseline.

Insulin is released by the Pancreas when you consume food. Most people are aware that Insulin is responsible for sending glucose and amino acids from the blood into muscle tissue, but that’s just part of its role.

Put simply, Insulin functions as a kind of “switch”, telling the body to stop burning fat and start burning glycogen (carbohydrate energy).

This makes perfect sense when you consider the fact that the reason your body stores fat is to provide an energy source when food is scarce.

Think of stored fat as energy being saved for a rainy day.

Energy is more easily obtained from carbs, so that is your body’s preferred source of energy. When carbs are low, however, your body has no choice but to start burning fat for energy.

What Does The Science Say About Fasted Cardio?

research on fasted cardio

Studies show that training while fasted increases fat-oxidation more so than training after consuming carbs.

It also improves Insulin Sensitivity and enhances the anabolic response to food, both of which make sense because if you temporarily deprive your body of the nutrients it requires, it learns to become more efficient when they’re made available again.

We are, after all, a product of evolution.  Humans would not exist if our body’s couldn’t adapt, at least to some degree, to food deprivation.

Unfortunately, there are downsides to fasted training…

When you train after not having consumed protein or carbs for several hours (fasted state), muscle breakdown is increased and muscular endurance is decreased.

This makes intuitive sense when you consider that, without proteins and carbs, your body lacks the substrates needed to build muscle and fuel your workouts.

Supplements The Help With Fasted Cardio

Fated Cardio Supplements That Work

Luckily, ther are some supplements that can reduce (or possibly eliminate entirely) the negatives and/or enhance the benefits.  The following supplements should be considered by anyone who engages in fasted training…

  • Leucine
  • HMB
  • Citrulline (Malate)
  • Rauwolscine

Each of these supplements has properties that make it especially useful for those who train fasted.  How?  Well, let’s get into the science behind each in order to fully understand how and why each of these supplements is worth considering by all those who train fasted…


Leucine is the most potent amino acid when it comes to stimulating muscle protein synthesis. It has been used clinically to the muscular wasting that occurs with certain disease states, and has been shown to increase muscle mass.

Unlike complete protein, Leucine has a minimal impact on Insulin levels, so it is capable of reducing the muscle breakdown that generally occurs when you train fasted without spiking Insulin and destroying the benefits that training fasted offers.

PrimaForce Leucine


There are many brands which offer affordably priced L-Leucine supplements, so just go with one you trust.  We recommend PrimaForce Leucine, but assuming high quality, all Leucine supplements are essentially the same.


The clinical range for Leucine is at least 3-5g.  You should consume this dose just prior to your fasted training session to minimize muscle loss and promote muscle protein synthesis.


β-Hydroxy β-methylbutyric acid, simply referred to as HMB, is a metabolite of Leucine which is believed to be roughly 20 times stronger than Leucine at preserving muscle.

Like Leucine, it has been used to reduce muscle breakdown when protein is lacking. To be clear, Leucine stimulates muscle protein synthesis to a much greater degree, HMB is just capable of preserving muscle.

Optimum Nutrition HMB


HMB is available in both powder and capsule form, but it’s worth noting that it tastes pretty terrible.  For that reason, we’d recommend going with a capsule form such as Optimum’s HMB 1000 caps (providing 1000mg per serving).


The clinical range for HMB is considered 1-3g.  You should ideally take it just before your fasted training sessions to minimize muscle loss.

Citrulline Malate

When it comes to enhancing muscular endurance, Citrulline reigns supreme. It has been shown to not only to increase Nitric Oxide production, but also to reduce Ammonia build-up in working muscle tissue, offering two mechanisms by which it can enhance exercise performance.

When you’re low on carbs, you will experience decreased endurance. So, supplementing with Citrulline Malate prior to your fasted sessions can improve your performance.

PrimaForce Citrulline Malate


Citrulline Malate is the ideal form of Citrulline to use since this was the form used in the majority of the studies in which Citrulline was shown to enhance aspects of exercise, although L-Citrulline may also provide benefits.

Generally speaking, you’ll find Citrulline Malate in either a 1:1 or 2:1 ratio of Citrulline to Malic Acid.  2:1 provides more Citrulline, so that’s what is recommended.


The clinical dose of Citrulline Malate (2:1) is 6-8g taken prior to working out.  It’s possible that lower doses have some positive impact on performace but it’s best to stick within the clinical range, just to be safe!


Rauwolscine is a potent alpha-adrenergic receptor antagonist, similar to Yohimbine, but much more potent. Alpha-receptors are responsible for putting a stop to fat-loss, so by antagonizing (blocking) them, Rauwolscine allows more fat-loss to occur during exercise than would normally be possible.

Yohimbine is effective as well, but comes with a long list of potential side effects and requires a much higher dose to achieve similar results. That’s why we generally recommend Rauwolscine over Yohimbine. It’s just better!



Singular Sport Rauwolscine was developed by yours truly.

What sets it apart from other Rauwolscine supplements is that it contains only Rauwolscine HCL, not from some question plant extract that is supposedly standardized for Rauwolscine but also contains numerous other active components that aren’t listed on the label.

Beyond that, it’s Third Party Tested, so you know exactly what you’re getting as well as what you’re not getting (heavy metals or contaminants).


There appears to be a lack of accurate information out there regarding the ideal dose of Rauwolscine as it pertains to weight-loss, but since it’s much more potent than Yohimbine, 1-5mg is the recommended range.

Most people are able to feel the effects of Rauwolscine at just 1-2mg, so we would not advise exceeding that range the first time around.

The Bottom Line On Supplements For Fasted Cardio

the bottom line on supplements fasted cardio

Fasted cardio—that is, cardio when Insulin levels are at their lowest—may be useful, but it has its downsides.

You may burn slightly more fat in a fasted state, but you’ll also lose muscle and not perform as well as you would in a fed state.

Consider any of the supplements discussed above for your fasted training, or look for multi-ingredient supplements that utilize these ingredients at clinically effective doses.

The truth is, much of the downside risk with fasted cardio can be negated through proper supplementation.  This is one of those rare situations where you can have your cake and eat it too.

Don’t get me wrong…

Fasted cardio still sucks while you’re doing it, but at least the supplements we discussed above can help you:

  • Burn more fat
  • Preserve muscle
  • Perform better

We tend to criticize supplements and say they’re unnecessary most of the time.  It’s definitely true that many supplements are over-hyped and unnecessary, but if you’re doing fasted cardio regularly, you stand to benefit immensely from taking the right supplements.

Have any experience with fasted cardio?  Which supplements do you find most useful?  Comment below…

I’m Matt Theis, founder of SuppWithThat, Momentum Nutrition, and Singular Sport. I created SWT to separate the science from the hype and publish accurate, research-based information on supplements. If you like what I have to say here, feel free to check out my supplements at and

Click to comment
To Top