Training Fasted? Consider Whey Protein Instead of BCAAs

Is it better to take Branched-chain amino acids (BCAAs) or whey protein when training fasted? Though the difference in outcome is likely small, it is exactly this kind of question that clients pay me to know and advise them on.

If you do your weight training fasted (in the morning without having eaten anything prior), it is advisable to take either a scoop of whey protein or BCAAs prior to training to minimize muscle breakdown.

Up until the end of last year, I recommended BCAA supplementation to clients who trained fasted. However, after a conversation with sports nutritionist and researcher Alan Aragon, I decided to change the recommendations I give to clients to favor whey instead.

This article explains my reasoning for this and the protocols I recommend for both the whey and BCAA supplementation.

Note: I have updated the BCAA energy values since the original publication. The article reflects these changes. I’ve added a note at the end explaining the reason why.

Why Whey Protein May be Better Than BCAAs When Training Fasted

Many of my clients are high achievers with demanding jobs. The majority choose to train early in the morning before the working day zaps their energy and motivation to train. They do not have any time to consume (and start to digest) a meal before training, which leaves them without any amino acids (the building blocks of protein) in circulation in their bloodstream to prevent muscle breakdown

This is where BCAA supplementation comes in as a recommendation. As the most important amino acids for muscle building, a BCAA powder can be consumed easily before training and absorbed quickly.

Typically, people who choose to train fasted in the morning will consume a 20 g dose of BCAAs split before and after their workout, with those that train very early in the morning consuming an additional 10 g due to the longer time until their lunch. This part of Martin Berkhan’s ‘Leangains’ protocol for his clients that train in the morning which I chose to adopt for my clients myself.

As you can see from the client results, this has worked well. Very well. So, this is not a question of whether this ‘works,’ it is merely a matter of whether whey consumption may be slightly more optimal.

BCAAs vs Whey: Comparing by Caloric Values

Contrary to what many products have on their labels, the free-form BCAA powders that we buy are not calorie free. They have a caloric value of 4.65 kcal/g, which means the typical 10 g serving has 46.5 calories. Geeky details here→1

So, why can manufacturers get away with not listing this on the packet you ask?

Because of a loophole in the FDA regulations. One states that supplement manufacturers can’t declare the protein content of a product when this only contains individual amino acids. Another allows supplement manufacturers to calculate the caloric content of their products using a number of methods, including the Atwater method, which involves adding up the calories from protein (4 kcal/g), carbs (4 kcal/g) and fats (9 kcal/g). Therefore, they aren’t required to list the calories. Shady shit, but to be expected from supplement manufacturers.

Though products vary, a standard commercial mix of whey concentrate and isolate (Optimum Nutrition Gold Standard Whey) has 120 kcal listed with 24 g protein per scoop.

Comparing the average BCAA formula with the average whey protein, we get the following:

10 g BCAA = 46.5 kcal = 0.37 scoop of whey = 9.3 g protein

20 g BCAA = 93 kcal = 0.77 scoop of whey = 18.6 g protein

30 g BCAA = 139.5 kcal = 1.16 scoop of whey = 27.9 g protein

The key difference is that with whey, we get the rest of the essential amino acids (EAAs) plus other anabolic/anti-catabolic co-factors that are missing in isolated BCAA, such as lactoferrin, beta-lactoglobulin, alpha-lactalbumin, glycomacropeptide, and immunoglobulins (hence its ability to support immune function). Whey also has antioxidant, antihypertensive, anti-tumor, hypolipidemic, antiviral, and antibacterial properties. You’d also be hitting the acute dosing ceiling for muscle protein synthesis with a full scoop.

In summary, taking whey protein costs less and you will get a marginally stronger anabolic response.

Fasted Training Supplementation Protocol Recommendations

Best option: Whey protein

Take a 25 g scoop of whey around 30 minutes prior to working out. Then take another 25 g scoop every 3 hours after that until your first meal of the day.

Count this against your protein targets for the day.

Second-best option: BCAAs

Take 10 g of BCAAs, (1 small scoop mixed in a 500 ml water bottle) 10 minutes before your weight lifting workouts. Take 10 g of BCAAs every 2-2.5 hours thereafter until your first meal of the day.

Because they have a caloric value, for every 10 g of BCAAs you consume, reduce your calorie intake by 46.5 kcal, by reducing your fat or carb intake (not your protein intake).

So, let’s say that you take 30 g of BCAAs, that’s ~140 kcal you need to remove from your diet. This can be achieved by reducing your carb intake by 35 g, fats by ~15 g, or a mix of both.

For more useful graphics, check out my Instagram.

Fasted Training and BCAA vs Whey FAQ

This section contains questions I anticipated, with the best I received from social media and email after the article’s publication.

Why should I not count BCAAs towards my protein intake target?

BCAAs are an incomplete protein, not as anabolic as whey alone. Therefore, I would not count the BCAAs against your protein targets for the day, but subtract them from the other macronutrients (carbs and fats).

Should I take whey concentrate, whey isolate, or hydrolyzed whey?

Whey concentrate and isolate will both digest in around 30 minutes. Isolate is a little more expensive but has fewer carbs in the mix, so it is worth consideration, especially when dieting.

Hydrolyzed whey is similar to whey isolate, but the protein has gone through a process called “enzymatic hydrolysis” which makes it faster to digest. It’s significantly more expensive, so unless you have less than 30 minutes between your alarm and the time you’re lifting something heavy, I don’t bother.

Can I take casein protein instead?

Whey and casein are both high-quality protein types (meaning they have an amino acid profile high in BCAAs). The difference is primarily in the rates of absorption, which will be significantly slower for the casein. As we want the amino acids to be in the bloodstream as quickly as possible when training fasted, whey protein is the best option.

Will this not ‘break’ my fast? I take BCAAs to not break my fast.

In both situations, you are no longer training fasted. (Yes, BCAAs have a caloric value but some manufacturers do not list it on the label. – This is something that caught me off guard for a long time also.)

If you want to train truly fasted, then you need to drink only water prior to training, which is simply not optimal. Why? Because what we are seeking to do here is minimize muscle breakdown during workouts (and promote growth, when possible).

Break your fast or break (down) your muscles. Choose wisely.

I am lactose intolerant and cannot consume whey shakes. Is there anything you recommend as an alternative?

A 70:30 mix of pea and rice protein closely mimics the amino acid profile of whey. You can order custom blends from a number of stores, I’ve heard good things about True Nutrition.

Given that the recommendations were originally part of Martin Berkhan’s protocol, what does he think of this?

I asked him to take a look at this before publishing to see if I had missed anything. He said it ‘looks good.’ I’m sure any updated thoughts from his original 2008-2010 articles will be included in his book.

What about BCAA supplementation outside the context of fasted training?

Completely fucking useless. Unless you’re not consuming an adequate amount of protein in your diet in the first place, but in which case, just eat more protein as it has more anabolic properties. Or just keep paying for this expensive, high-calorie, flavored drink that is costing you other food options in your daily caloric budget. It’s your choice, but make the decision an educated one.

It is at this point where I typically hear a rebuttal along the lines of the following: “But I feel so much more energized when I take BCAAs!”

That’s the caffeine in that BCAA product you are using (take another look at the label), some added arginine (or citrulline malate) causing your skin to tingle, or just a placebo effect – which I guess I’ve just killed for you.

What should I do if I have some leftover BCAA powder?

When it runs out, just switch. The difference is likely there, but marginal.

Do I have to supplement with whey or BCAAs for my fasted cardio workouts?

No. Fasted cardio won’t amount to the kind of stimulus where you’ll risk significant muscle breakdown, like with an intense resistance training workout.

What if I don’t want to train fasted?

That’s fine. I’m not telling you to and it’s not likely to give you a better result if all other variables are held constant.

However, if your workouts are currently compromised due to being rushed in the middle of the day, or you lack the energy after work in the evenings to train hard, this could be the answer as it has been for so many of my clients.


Thank you for reading. Questions welcomed in the comments.

– Andy


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  1. Leucine and isoleucine each have a gross energy of 6.52 kcal/g; valine has 5.96 kcal/g when protein bound. The metabolizable energy is slightly lower, 6.18 kcal/g and 5.55 kcal/g respectively.

    However, the free-form energy values in the BCAA powders we buy are 4.65 kcal/g, 4.65 kcal/g and 4.64 kcal/g for each of the three BCAAs respectively. Here’s the paper from where these numbers are derived.

About the Author

Andy Morgan

Hi, I'm Andy, co-author of 'The Muscle and Strength Pyramid' textbooks and founder of This site is my sincere effort to build the best nutrition and training guides on the internet. Some readers hire me to coach them, which I've been doing full-time, online, for the last seven years. If you're interested in individualized, one-on-one coaching to help you crush your physique goals, let's start the conversation. (You can read more detailed bio here.)


  1. Tee says:

    How about EAAs? They make them in the same powder form as BCAAs, just they are EAAs. Isn’t that the main reason for the Whey?

    Thanks Andy!

    1. Andy Morgan says:

      You can consider EAAs to be the halfway house between whey and BCAAs as an option. They still have a similar caloric content, even if labeling laws allow manufacturers in some countries to get around it.

      Here’s a key part from above:

      “The key difference is that with whey, we get the rest of the essential amino acids (EAAs) plus other anabolic/anti-catabolic co-factors that are missing in isolated BCAA, such as lactoferrin, beta-lactoglobulin, alpha-lactalbumin, glycomacropeptide, and immunoglobulins (hence its ability to support immune function). Whey also has antioxidant, antihypertensive, anti-tumor, hypolipidemic, antiviral, and antibacterial properties. You’d also be hitting the acute dosing ceiling for muscle protein synthesis with a full scoop.”

      1. Tee says:

        THANK YOU!

  2. Natan says:

    Thanks for the tips! I usually take 5g of creatine, 8g of L-Citrulline, and about 8g of BCAA’s (because the pure powder tastes so stinking bad I cannot add more than that.) Wouldn’t I start a significant digestion process if I take 30g of BCAA or 1 scoop of protein (I train in about 20-30m right after I wake up), which could put blood flow in the gut rather than in the muscles? Thanks!

    1. Andy Morgan says:

      Though you haven’t asked it in the same way, I think point 4 in the FAQ answers your concern.

  3. Suzan Momin says:

    Hi, Andy.
    Thanks for the great article,I am 33 years old male and doing weight training for past 6 months, Mon to Sat, FASTED (I do not eat but sometimes drink some water if feels thirsty ). I wake at 6:15 am and start exercise around 6:30 am and finish around 8:00 am. and have breakfast around 9:30 am. I am planing to use supplement (Whey Protein) first time in my life. I want to know when should I take whey Protein, immediately after I wake, during workout or after I complete my workout.
    Thank you!

    1. Andy Morgan says:

      Hi Suzan, see the section titled: “Fasted Training Supplementation Protocol Recommendations”

  4. PDarla says:

    Hi Andy, I’m a 50 year old female. I workout Mon-Fri (mostly strength and a bit of cardio). I do strict IF (16/8, nothing before or during my WO). I’m lean, but can’t seem to get rid of access belly fat and I haven’t been gaining much muscle. What would you recommend? Any tips?

    1. Andy Morgan says:

      Hi PDarla,
      You’re not losing weight because you’re not currently in a calorie deficit. To do that, you’ll need to start counting calories (and know how to set them), which I have covered in the guides I’ve just linked to.

  5. Pascal says:

    Thanks for the great article, Andy. I purchased the Muscle and Strength Pyramid textbooks a few years ago (the second editions are even better) as I follow Eric Helms and they brought me to your site.

    I have a question regarding ingesting carbs with your recommended 25g of whey pre-workout. Would, say, 25g of oats or a banana slow down the whey absorption? I’m also in the ‘can-only-train-first-thing-in-the-morning’ camp and understand that carbs pre-workout enhance performance. Only thing, I’d be reluctant to wake up even earlier to get the nutrition in if carbs did slow down whey protein absorption.

    1. Andy Morgan says:

      Hi Pascal,

      Mixed meals generally slow protein digestion.

      Unless you’re an endurance athlete or glycogen depleted, there is unlikely to be any benefit to having carbs prior to working out when training ‘fasted’ (early in the morning having eaten nothing else) like that. Besides, you simply don’t have enough time to digest and store them for utilization anyway. Keep to the whey.

  6. Julia says:

    Hey Andy,
    I have read a lot of your articles (and comments) and learned so much. I workout at 12:00pm but wake up at 6:30am. I was wondering if I can drink whey&coffee pre workout, but around 8am, and then Whey (with water) again as a post workout drink directly prior workout, and then eat 1st meal 2 hours later. This isn’t fasting, but should keep my body in a fat burning state right? To achieve an optimal anabolic state.
    Thank you!

    1. Andy Morgan says:

      Hi Julia,
      Any calorie consumption is no longer fasting. The question you have to ask yourself is, does it matter? The answer to that is, not really.

      Calorie balance throughout the day is what determines whether fat will be gained, lost, or not change. If skipping breakfast helps you create that caloric deficit by giving you a long period without food (and generally speaking, hunger), and allows you to have a lower meal frequency, which you find more mentally satisfying and satiating, which in turn, helps you adhere to the diet, do it. This is the advantage that morning fasts bring (barring exceptionally lean people trying to remove stubborn fat, there is no other utility.)

      The whey is there to put amino acids in the blood stream at a time you need them (when you train), thus preventing/minimizing muscle breakdown and promoting faster repair and recovery. Given this, I don’t see the point of the 8am whey. You end up eating less real food later in the day which leads to lower satiety and adherence.

      Also, though whey is the fastest digesting protein, you still need to give it time, so take it 30–60 minutes prior to working out. There is not really a benefit of having more protein after working out either, as you’ll be eating soon enough and the whey will still be digesting and delivering amino acids to the blood stream.

      If you workout at noon, you may as well just have the whey prior to your workout at ~11:00–11:30. Then eat within a couple of hours after working out. Boom.

  7. Aman says:

    Hey Andy! Bit confused about consumption of whey preworkout. Will it not negate the benefits of fasting(fat burning mostly) because obviously it will break the fast. I read where you said break muscle or break the fast. I’m somewhere around 15% as per your guidline I take whey 30 mins prior to workout and train at 8.30 then whey post workout and every 3 hours until I eat solid food around 2. If I don’t use whey pre and post and just break fast at 2pm, am I at risk of loosing too much muscle.
    Current goal is get down to around 6-7%. Thanks for all the info Andy

    1. Andy Morgan says:

      Will it not negate the benefits of fasting (fat burning mostly) because obviously, it will break the fast.
      – In this regard, morning fasting is overhyped. It won’t make a difference to total fat burned as long as the calorie balance is maintained throughout the day.

  8. Mike says:

    Hi, great article. Two questions: why the difference in time window between whey and BCAAs? Anything wrong with following the 2/2.5 hrs for whey?

    Also, what about HIIT? It’s very taxing, so I follow the whey protocol even though you said no need for cardio. Thanks!

    1. Andy Morgan says:

      Hi Mike,
      1. Different digestion rates (the BCAAs are free-form, protein that has already been broken down).
      2. If the kind of HIIT you’re doing leaves you sore, I could make a case for it.

  9. Patrick Norton says:

    Andy, thanks for this excellent and insightful article. I have a question based on this: I am one of those need-to-work-out-before-work guys, and I’m not looking to add bulk (yet) but to lose about 30 pounds first while strengthening up. I have read a number of articles championing BCAAs for the prevention of muscle loss during workouts while on a calorie deficit diet. Does your position include people who are looking to aggressively lose weight while adding muscle, or should I work first to meet my weight goal (including BCAAs) and then move to your strategy? Will whey protein also prevent my body from eating muscle mass to protect its beloved fat stores?

    1. Andy Morgan says:

      Whey is likely to be the best option, but if you have an aggressive deficit you’ll compromise what strength and muscle gains you can achieve while cutting and possibly lose muscle mass.

      The fastest way to your dream physique is not the one where the numbers move the fastest. Set your weight loss at somewhere between 0.5-1% of body weight per week. More in my guide on nutrition set up here.

  10. Preston says:

    Hey Andy. I scrolled through the first 40 or so comments and didn’t see anything mentioned about Optimum nutrition EAA’s so forgive me if it has been covered but whey protein always makes me fee sluggish shortly after taking it do you have any thoughts on OP EAA’s? Thanks

    1. Andy Morgan says:

      You can consider EAAs to be the halfway house between whey and BCAAs.

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