Dear Mark: BCAAs, and That Weightlifting Article with All the Exclamation Points

Dear_Mark_Inline_PhotoFor today’s edition of Dear Mark, I’m answering a pair of questions. First, a new study comes out and claims that branched chain amino acids increase the risk of insulin resistance and, eventually, diabetes. The study is legit, but the test subjects were mice. Is the research relevant to humans? Then I explain just why the interesting weightlifting article with all the exclamation points from last week’s Weekend Link Love got me thinking.

Let’s go:


I’m a little worried. I’ve been taking BCAAs for the past few months, mainly to reduce hunger and increase muscle retention during fasts. then this study hits claiming that low BCAA diets improve metabolic health. Should I stop?

First off, that was a mouse study.

The authors of the mouse study try to make their results relevant to humans, citing a human study in which elevated BCAAs in serum correlated well with insulin resistance. Other research finds links between elevated serum BCAAs and obesity and, at least in whites and Hispanics (but not blacks), elevated BCAAs and diabetes.

It turns out that serum amino acids are in constant flux, and many medical issues can determine which amino acids show up in the serum. Serum levels of BCAAs may not even necessarily reflect dietary intake. In obese women, for example, taking BCAA-rich whey had no effect on serum BCAAs. Assuming high BCAAs in serum cause and don’t just correlate with obesity and insulin resistance, it’s unclear whether eating more BCAAs necessarily elevates serum BCAA. 

What happens in humans (you are human, right?) who eat more BCAAs? Good things:

It activates the enzymes necessary for muscle protein synthesis post workout.

It reduces muscle damage after training.

It stimulates muscle anabolism in older women, with or without training.

As for the metabolic issues raised in the mouse study, we have some relevant observational studies on dietary BCAAs in humans:

In Japanese adults, high intakes of BCAAs are associated with lower rates of diabetes.

In middle-aged Eastern and Western adults, high BCAA intakes predict lower rates of obesity.

In Chinese adults, a higher ratio of dietary BCAA predicts lower rates of obesity, high blood sugar, and inflammation.

I don’t actually see a need for branched chain amino acid supplements in most people. They have very specific uses—staving off muscle loss and increasing muscle gain during fasts, especially when taken before training—but the majority of us get plenty of BCAAs in food form. Foods like whey protein, eggs, and most meat and fish are fantastic sources of BCAAs, and the observational studies finding beneficial links with high dietary BCAA are talking about those types of sources, not BCAA supplements. 

To sum up, you don’t have to worry. You’re using BCAAs for the right reasons, in the right manner.

In a Weekend Link Love comment section, David wrote this while referencing this article:

I’m with you, David. A joke of a post. Not sure why this drivel would get Mark “thinking.”

At this point, I should probably reiterate that “links are not full-throated endorsements.” I link to articles that contain interesting viewpoints. Sometimes I disagree with the links. Sometimes I agree with some of the content and disagree with the rest.

Here’s what I liked about the article:

The idea of gyms as an unnatural, artificial environment.

I don’t necessarily agree with this stance. I do most of my lifting in a gym, because it works and it’s convenient, but I also recognize that I’m doing something rather artificial. If I could I’d probably train outdoors every time. There are real benefits to that. As it stands, the majority of my play—Ultimate Frisbee, paddle boarding, hiking, slacklining, and any other non-gym physical activity—takes place outdoors in as close to a natural setting as possible.

“If you can’t shoulder it, you shouldn’t be working with it!”

This appeals to me. The ability to safely move a weight from the ground to your shoulder is a strong and probably reliable signal that you can safely manipulate it in other ways—squatting, pressing, pulling. It may not optimize your strength gains, but it’s a good heuristic for keeping injuries at bay while getting you strong “enough.”

The emphasis on loaded carrying.

From farmer’s walks to heavy rucking to carrying groceries to packing out the elk you just shot 4 miles from your car, we’re meant to lift things up and carry them for distance. It builds toughness, durability, places a unique 20-30 reps of squats while holding a heavy weight? Useful and beneficial, but evolutionarily novel. And a little odd; just imagine how a Hadza bushman would react to a CrossFit class.

The warning against letting your ego guide your training.

One of my worst training injuries happen years ago when I strained my shoulder going for a PR on the bench press. I didn’t have any real “reason” to train so hard. I didn’t “need” the big bench. It’s important to be strong, and given the choice I’d prefer to be stronger than not, but that mentality, taken to the extreme in service of the ego, will almost certainly lead to injury.

The exclamation points.

It’s refreshing to see a guy go through an entire blog post at the top of his lungs.

Is it a flawed blog post? Absolutely. Does it contain useful concepts? Yes. The cool thing is that you can take the stuff that resonated and discard the rest.

Thanks for reading and asking, everyone. Take care and be sure to comment down below!


TAGS:  dear mark

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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27 thoughts on “Dear Mark: BCAAs, and That Weightlifting Article with All the Exclamation Points”

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  1. Thanks for your broader discussion on the weight lifting article, Mark. What you expressed is basically what I took away from the article. Yes, training inside is unnatural, but necessary for most, including myself, and we should focus more on carrying weight. I have been doing that very thing, walking for 30-1hr before lunch (my first meal) every day with 25lbs in a backpack and stepping up to 40 starting today, as well as hikes on the weekend and walks in the neighborhood at night with a 40lb weight vest. There are valuable take-aways from that article, but as you pointed out, they were veiled. Thanks for being willing to take a deeper dive on all subjects!

    1. What a splendid article on carrying and working outdoors. It reads like something I would publish, then edit after the testosterone crash to remove the f-bombs and add weasel words.

      The anthropology of carrying is an extremely deep subject rarely investigated, and I’m stoked to see Mark touch it even tangentially.

      Unlike running, when our weight is fixed and we push for a faster pace, with carrying, the pace is fixed and we push for more weight.

      This produces significantly different adaptations than running and any scientifically minded athlete ought to compare and contrast both experiences. Curtis and I have both registered significant carryover to heavy lifting, for example.

      In my research, anthropology supports carrying as the fundamental hominin adaptation, with sprinting, running, climbing, lifting etc. as accessories.

      Mark, would you be game to address this subject some day? We would benefit from your informed perspective and particular methods of inquiry.

      1. As I suggested in another post, I would love to see either Mark take a deeper dive into carrying or let you tackle the topic in a guest post, Timothy. The Primal masses are missing out on this ancestral activity!

  2. re: First off, that was a mouse study.

    And perhaps the top problem with rodent trials is not the species biology, but that the vast majority of rodent trials use standard lab chows, with variations. These chows are horrible – loaded with simple carbs (sucrose in this case), industrial grain and legume oils, etc. Very few researchers (D’Agostino is one) seem to have any clue on this. The adverse components of the chows add needless noise to the data set.

    So any interesting rodent trial really needs to have its results replicated with a more native rodent diet, then, if confirmed, followed by a human study.

    1. Bob, you make a crucial point: the universal convention of feeding control rodents junk food confounds results. At best, the results can be generalized only to humans who eat junk food.

      However, the paleo rodent diet is very different than the paleo human diet. Granivorous scavengers are adapted to a different balance of nutrients and antinutrients than alpha predators. For example, we expect rodents to tolerate chronic carbohydrates, phytates and lectins better than humans.

      The obese and ill mouse may have much in common with the obese and ill human, but the optimal mouse and the optimal man have significant metabolic differences.

      If we want results applicable to real humans, we have to test on real humans, and that means you and me.

    2. Of course, the terrible chows do a pretty good job of mimicking the circumstances of most people in the first world. So, there’s that.

      1. re: “terrible chows do a pretty good job of mimicking the circumstances of most people in the first world.”

        True, and if the researchers stick to single variable trials, sometimes they can tease out a real difference in outcomes. But readers of sites like this one are more concerned about whether the effect still exists and actually matters for those on enlightened ancestral diets. And since it is rarely obvious, they have to write Mark about it. 🙂

  3. Regarding BCAAs and “excessive” protein:

    There is a lot of concern in some quarters (Mercola) about the alleged aging effects of high protein in general, and mTOR activation in particular.

    We have also heard that the organisms that secrete the least insulin live the longest.

    Though this seems to be true ceteris paribus, it is not the whole picture.

    We refer to the Triage Theory of Aging: Bruce Ames’ observation that subclinical nutrient deficiences drive long-term pathologies like CVD, bone and joint degeneration, hormonal resistance etc.

    We observe that growth is a very metabolically expensive process requiring elevated micronutrition.

    We conclude that concerns about excessive growth and high protein should more properly be targeted at supplying the micronutrition to support such processes.

    We feel that growth, strength gains, and a high-protein diet are compatible with longevity provided micronutrition is properly addressed.

    We find that, once again, all roads lead to raw liver.

    1. I am reading through Dr Longo’s new book right now. He is a serious, creative scientist and he’s logged many miles to the current pinnacle of “longevity” knowledge. The evidence regarding the LCHF is disconcerting and his position is probably not that of people who follow MDA. As an older person and involved in significant weight training to build muscle and increase strength, I am also concerned about the statistics on increased protein diets…..and our family eats significantly more than he recommends .

      What he should know but is not properly sorted out….is that mTOR activation in the context of strength training is LOCAL (to the trained tissue) as is increased IGF-1 and other anabolic signalling molecules. He assumes that people not building muscle and eating protein having mTOR and IGF-1 in the serum …..presumably a bad thing for longevity. Maybe he is right in that context. However, strength training also lowers resting cortisol and serum insulin, and it reasonably well established as decreasing all cause mortatlity across the board. I have seen no studies yet associating weight training to “longevity”.

      I am hoping when he gets to the punch line later in “Chapter 7” where he says that “activity” will be considered to be essential in conjunction with his dietary recommendations, that we will get a more nuanced view of this longevity issue.

      You keto people out there are going to get absolutely NO LOVE from Dr Longo…..except for weight loss.

      1. Weight training’s results (adequate to high skeletal muscle) is a huge indicator of longevity, as you explained, as a glucose sink, and healthy part of being a human. Over training and causing stress is not good for longevity. There are papers on these 2 points, and also that high ketones levels contribute to longevity – I think the best way is thru periodic fasting which depletes igf1 and excess protein, and resets hormones.

      2. Not familiar with Longo’s work, but what is his “disconcerting evidence” regarding LCHF?

        mTOR is elevated by dietary leucine so this is may be his cause for concern. Others might see it as an opportunity.

        There is also a common fallacy of looking only at the quantity of hormones such as IGF-1 in the bloodstream without accounting for sensitivity. Obviously, it is much easier to measure the amount of serum IGF-1 than to count the receptors in every cell in the body, much less compare them to a standard model. But as we know from insulin — and as fewer know with regards to androgens — receptor sensitivity across various tissues is a deciding factor for whether a hormone’s effects are adaptive or maladaptive.

        1. I agree with your comments….measuring systemic (serum) markers is tricky business and ignores the receptor issue as well as alternative pathways for enzymes and molecular processes…also target tissue dependent. Revving up mTOR by weight training and protein supplementation may be very different than another context (ie feeding face).

          His LCHF disconcerting evidence is based on his research with simple cell organisms, rodent experiments, and epidemiology studies. In addition, he is now very active in low calorie fast mimicking with low carb rx….in cancer treatments for humans. The results have been phenomenal.

          Please listen to his very recent podcast interview of the entire subject with kevin Rose

      3. I would hope that Mark take a short (miles) long (drive time) trip across town to have a face to face with Dr Longo and discuss what constitutes a “healthy ” diet. They seem to be diametrically opposed, although possibly some points of agreement possible.

  4. Working out in a gym is unnatural? By the same token it could be said that living in a house is unnatural.

  5. Goodness, that’s a bit disconcerting, a whole screen of blue shirted Mark Sissons
    So early in the mornings, reinforcement in a visual way.

    1. I have been doing daily IF for years and have played around with BCAAs a lot. I do dirty refeeds on heavy training days use BCAA during workouts.

      I always notice what feels like an insulin spike after drinking BCAA. I also notice an energy crash when trying BCAA without any stimulants.

      I have read someplace that BCAA supplements induce hunger which makes sense if they play with insulin.

      My recommendation is coffee black, water , and water with himalayan salt during fasts. Save the BCAA for the gym.

  6. Weight training ,if done correctly and supervised, programmed, etc… not exactly exercise. It is training…and as such a program to consistently increase muscle mass and quantifiable strength gains with consideration for safety through measured incremental loading. there are plenty of other benefits to this kind of training…in fact, too many to mention here. Strength training is ideal where there are power racks, barbells, and iron plates.

    Outside activites like rock climbing or whatever you wish to do that’s strenuous and requires strength are a different matter. Of course healthy in many ways but not the same.

    A gym, although “unnatural”… not the issue, per se. Although there are are hazards to a gym, not to mention communicable diseases…and even “eyestrain”…if too many fit young women.

  7. Nice!!!!!!!!
    So glad to be back and back on track.
    Hope everyone is having an awesome day.

  8. It’s interesting that elevated serum BCAAs -correlate- with obesity. The correlation possibly can be explained easily. insulin not only shuttles glucose into cells, but it also shuttles BCAAs into cells. If a person is obese, there’s a good chance the person is insulin resistant. If the sugar can’t get into the cells due to insulin resistance, the BCAAs probably can’t get in either, right? It would be interesting to see if the elevated BCAAs also correlated with elevated blood glucose. If so, there’s a good chance it’s not the BCAAs causing the problem.

    1. If you just overload on BCAA’s and don’t use amino acids to build new proteins for muscle tissue (by training), it’s just another energy substrate surplus to hide away. The body will try for as long as possible to protect itself with “insulin resistance”.

      My guess it is not just BCAA.

  9. I am a little confused. Are you giving a thumbs up to the Farmer’s Walk?

  10. You can get more with honey then with vinegar. The weight lifter has a point but he should work on his delivery and use finesse, instead of shouting at the top of his lungs.

  11. At the risk of sounding like an anal-retentive jerk, the BCAA study was NOT a mouse study.

    It was a rat study. 🙂