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RHR: How to Gain Weight on a Paleo Diet


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Revolution Health Radio podcast, Chris Kresser

This is a question that I get fairly regularly.  I think in part that’s because the population of people who read my blog and listen to my podcast and follow my work is not necessarily the typical standard American population.  Weight loss is definitely a concern in my world, but it’s not as much of a concern as you would expect, given the statistics on an overall basis in the US.  I probably get a question a week or every other week about how to gain weight on paleo.  I think I have a lot of lean, active people in my audience, athletic people, people who are training hard and involved in sports and things like that, and when they switch to paleo, sometimes they actually lose weight.  That’s what happened to me, as a matter of fact, when I first switched to a paleo type of diet, and part of my journey in terms of expanding paleo to be more of a paleo template in part was spurred by the weight loss that I experienced following a strict paleo diet, so this is definitely something that I have some personal experience with, and I also have clinical experience in terms of my work with patients.

In this episode, we cover:

5:23  Why you may be underweight
17:24  Is being underweight actually a problem?
20:12  Strategies for gaining weight on a paleo diet

Full Text Transcript:

Steve Wright:  Hey, everyone.  Welcome to another episode of the Revolution Health Radio Show.  This show is brought to you by ChrisKresser.com, and I’m your host, Steve Wright from SCD Lifestyle.  With me is integrative medical practitioner and New York Times bestseller, healthy skeptic Chris Kresser.  Chris, how are you today?

Chris Kresser:  I’m great.  How are you doing, Steve?

Steve Wright:  Pretty awesome.  I’m on my second cup of coffee, so my mind’s ready to go today.

Chris Kresser:  Oh, yeah.  You’ve been reading all that research we talked about, about how good coffee is for you, huh?

Steve Wright:  Exactly.  I’ve been doing IVs of it.

Chris Kresser:  I guess you’re not one of those unfortunate people with trashed adrenals… or you are and you’re ignoring my advice!

Steve Wright:  Yeah, I could be doing either.  I’m still on the mend from the leaky gut launch.

Chris Kresser:  Right.  Yeah.

Steve Wright:  I’m on the upswing.  I limit myself to two cups a day before noon.

Chris Kresser:  All right.  That sounds fair.  Let us know how it goes.

Steve Wright:  OK.  We’ll go week by week and see what happens!

Chris Kresser:  All right, so we have a great question today.  It’s not a question that’s going to apply to everyone, that’s for sure, but it’s one that we get quite a bit and it’s actually something that I’ve struggled with myself.  This is my show, after all, so we’re going to talk about it, and I have some personal experience with it, so we’re going to give it a shot.  Let’s have a listen.

Question from Robert:  Hi, Chris.  This is Robert.  I’d like to ask you how to gain weight on a paleo diet.  I’m one of those skinny guys who really would like to gain weight but I didn’t succeed so far.  I noticed that all the attention usually goes to losing weight, and paleo is particularly advertised to be good for that.  Fortunately I didn’t lose weight, but I didn’t gain either.  I’m convinced that being skinny isn’t that unhealthy like being heavily overweight, but I’m sure it isn’t healthy either, and most of all, it doesn’t really look good.  So for all those people who are with me in the problem of wanting to gain weight, I would like to ask, please help us.  How can we gain weight on paleo?  And in particular, I would be very interested in how can one gain weight without adding too many carbs?  What else can one do?  Thank you so much.

Chris Kresser:  OK, so as I said, this is a question that I get fairly regularly.  I think in part that’s because the population of people who read my blog and listen to my podcast and follow my work is not necessarily the typical standard American population.  Weight loss is definitely a concern in my world, but it’s not as much of a concern as you would expect, given the statistics on an overall basis in the US.  I probably get a question a week or every other week about how to gain weight on paleo.  I think I have a lot of lean, active people in my audience, athletic people, people who are training hard and involved in sports and things like that, and when they switch to paleo, sometimes they actually lose weight.  That’s what happened to me, as a matter of fact, when I first switched to a paleo type of diet, and part of my journey in terms of expanding paleo to be more of a paleo template in part was spurred by the weight loss that I experienced following a strict paleo diet, so this is definitely something that I have some personal experience with, and I also have clinical experience in terms of my work with patients.

Steve Wright:  Yeah, I’m excited for this.  I think this is a very underserved topic and an underserved niche.  Jordan struggled with this for many years, and so I did a lot of research trying to help him.

Chris Kresser:  Right.

Steve Wright:  And it seems like those people who go undiagnosed with autoimmune conditions for a long time either balloon up one way or balloon down the other way, and then they’ll have weight issues to come back to at some point.

Chris Kresser:  Absolutely, and yeah, there are definitely certain issues that don’t get discussed as much.  Another one is the poor people with hyperthyroidism.  We’re always talking about hypothyroidism, and hyperthyroidism is a lot less common but it’s arguably a more serious condition than hypothyroidism.  I think it definitely is.  So remind me, Steve, we need to do an episode on hyperthyroidism in the future and give them some love!

Why You May Be Underweight

Before we get into strategies for how to gain weight on a paleo diet, let’s talk a little bit about why someone might be underweight and what the issues might be there that don’t necessarily directly relate to diet because I think that’s the first question you need to ask if you’re having trouble gaining weight.  Is this a problem?  Is it physiologically something that’s going on that’s preventing me from gaining weight, or is it simply a genetic issue or a metabolic issue?

Statistically speaking, as I mentioned in the beginning of the show, this isn’t a huge problem.  Fewer than 2% of people in the US are classified as underweight, and that’s defined as having a body mass index of less than 18.5.  For a woman, for example, who is 5’6″, she would have to weigh less than about 114 pounds to qualify as being underweight.

In terms of causes, there are actually several things that can contribute to this.  I mentioned the first one just now, which was some people are just born with a faster metabolism, basal metabolic rate, than others.  That can be in part genetically determined, and those people from birth will be naturally lean and naturally have a hard time putting on weight, so that’s definitely a factor.  But there are other potential causes.  One of the main ones would be gut issues, particularly malabsorption.  We see this in celiac disease and non-celiac gluten sensitivity and then with other food intolerances like lactose intolerance or intolerance to any cross-reactive proteins with gluten.  What happens here is if you’re eating these foods and you’re not aware that you’re intolerant of them, it causes a chronic inflammatory situation in the gut, which can then interfere with absorption of the nutrients that we need to gain muscle and weight.  These people typically will not only be underweight, they’ll have a really low muscle mass.  They’ll be thin – not necessarily thin and wiry and strong, but they’ll be thin and have less than average muscle tone and muscle mass.

Another gut issue that can cause difficulty gaining weight is small intestinal bacterial overgrowth, SIBO.  When bacteria are overgrown in the small intestine, they compete for absorption of key nutrients with us, and they tend to win that battle because they’re living right in between the nutrients, which are in the –

Steve Wright:  They get first dibs!

Chris Kresser:  Yeah, they get first dibs.  That’s a lot more clear way to put it!  And they take what they need and we only get what’s left over.  I do a lot of nutrient testing in my practice, and I can tell you that almost without fail people who have SIBO have deficiencies of multiple B vitamins.  They’re often deficient in vitamin D.  They’re often deficient in minerals.  They typically can have low amino acids even on a paleo diet, which is really interesting because if someone is eating a lot of protein, you would expect them to have normal amino acid levels since amino acids are just breakdown products from protein, but what’s happening in these people is they have low stomach acid and the bacterial overgrowth in the small intestine, they’re not able to break down the protein that they’re eating into the constituent amino acids and absorb them effectively.  So you almost have a situation where people are not necessarily protein starved, but it looks as if they’re on a vegetarian diet even when they’re eating a paleo type of diet.

Intestinal permeability or leaky gut is another problem that causes inflammation and difficulty absorbing nutrients and gaining weight.  Dysbiosis, which is a disruption in the gut microbiome, can cause that problem, and I’ll talk a little bit more about that later.

So for sure, if weight gain is an issue, you want to be looking at your gut health and following all the suggestions that we’ve talked about many times on the show and I’ve written about and talked about in my book, and then you may want to reach out and get some help from a functional medicine practitioner so you can do some testing, some stool testing, urine organic acids testing, maybe a SIBO breath test, and figure out if you have any of these conditions and treat them, because if you do, it’s going to make it harder for you to gain weight.  Now, clinically what I see is it may not be a dramatic difference, but it may be the difference between being able to gain weight and not being able to gain weight.  In other words, if you’ve been a lean, fast metabolism person your whole life and then you treat your gut and you have gut problems that are interfering with being able to gain weight and to treat your gut, you’re not necessarily going to become Arnold Schwarzenegger.  Your whole body type isn’t going to change, but you will probably be able to put on some weight even if it’s a little bit and, in particular, muscle where you weren’t able to do that before.

Steve Wright:  Yeah, that’s definitely, I think, too, for those people who are eating 3000-plus calories a day on a paleo diet and they’re still not seeing any fat gain or seeing no gain at all when they’re calories are 3000 or 4000 calories.

Chris Kresser:  Yeah.  Jordan’s a good example.  He used to be really thin, right?  And now he’s not.  I mean, he’s lean.  His body type didn’t just completely change dramatically, but he’s not anywhere near as thin as he was when he was really sick.  That’s a good example.  I’m an example of that, too.  I have this picture of myself when I was in Thailand doing a meditation retreat in the kind of deepest, hardest part of my illness, and I look like Lurch because my head is shaved, my eyebrows are shaved.  It was a long, 30-day meditation retreat, and I had to follow the traditional practice.  I had my shirt off, and I literally looked like I had just come out of a POW camp or something like that.  It was crazy.  And now, if you know me, I’m still very lean, but I have a lot more muscle on my frame and I look different than I looked then.  So it will be a difference, but it won’t be night and day.

Steve Wright:  Well, it is still night and day, though.

Chris Kresser:  Right, it is night and day

Steve Wright:  I mean, it’s still 30 pounds plus.

Chris Kresser:  Definitely.  It is for me.  But what I’m suggesting is that body type isn’t necessarily going to change, although in an example I’m going to give later on, there’s been at least one case where I have seen a pretty significant shift in body type and possibly even bone structure, which is really interesting.

Steve Wright:  Are there secondary causes now of this that stem out from the gut relating to hormones just because of all the inflammation and everything?  Is that where we’re headed next?

Chris Kresser:  Yeah, related to the gut there are other possibilities here.  You can get adrenal fatigue and make it hard to gain weight, hormone imbalance.  Just the chronic low-grade systemic inflammation can contribute to both weight loss and weight gain.  We also see weight gain with these conditions, and whether someone goes to weight loss or weight gain probably depends on their phenotype and epigenetics and a whole bunch of other factors.

Autoimmune disease, as you mentioned, Steve, is another potential cause of difficulty gaining weight, and that can also be a cause of difficulty losing weight, but I’ve seen it work both ways.

Hyperthyroidism is a well-known cause of weight loss.  It’s not that common, but it is a possibility, and I have detected it in people who didn’t know they had it before.  Often hyperthyroidism is pretty noticeable when you have it.  You’ll have pretty severe symptoms and the kind of symptoms that spur people to go to the doctor and figure it out, but that’s not always the case.  There are lower-intensity versions of hyperthyroidism where TSH is only moderately low and T4 and T3 are only moderately high and people have it and don’t know it, so it might be worth getting screened for that.

Chronic infection is another common cause – or at least more common than a lot of people know or believe – for weight loss.  This can be infections like H. pylori, a bacterium that causes ulcers.  They could be more stealth infections, which are infections that are difficult to diagnose, such as Lyme disease or Bartonella or intracellular infections like mycoplasma, Chlamydia pneumoniae.  A lot of these infections that can be chronic and insidious in the sense that they’re not easily detected, they’re not often on the radar of people in mainstream medicine, and people who have them can really run the gamut in terms of their presentation.  Of course, Lyme can be extremely serious and even fatal in some cases, but in other cases it just causes a range of nonspecific symptoms that really drag people down but don’t present as really serious, severe illness, and that’s also true for things like Chlamydia pneumoniae and mycoplasma and even H. pylori, for that matter.  H. pylori, of course, can cause gut symptoms, but it’s also associated with a whole bunch of other things like skin problems, brain fog, cognitive issues, and immune dysregulation.  Then you have viral infections.  Chronic latent viral activity is another potential cause.

Type 1 diabetes, which is an autoimmune disease, but a specific one that can make it difficult to gain weight.  Neurological issues, which can be autoimmune in origin, like MS or epilepsy.  Things like that can also make it difficult to gain weight.

As you can see, the number of potential issues here is overwhelming, and I guess from a practical perspective, what you’d want to do is go through this list that we just went through and think about your symptoms.  If you’re completely healthy and difficulty gaining weight is your only complaint and you have no other health complaints, it’s fairly unlikely that you’re dealing with any of these other problems.  I mean, it’s possible but it’s pretty unlikely.  However, if you’re listening to this and you’re like, wow, yeah, I have a lot of gut symptoms – gas, bloating, constipation, history of gut problems, took a lot of antibiotics when I was young, ate a really poor diet when I was young, then, of course, you probably should be thinking about gut as a potential contributing factor here.  If you have symptoms of chronic infection like low-grade inflammation, muscle aches and fatigue, general malaise, weak immune function, neurological issues, that sort of thing, then you may want to investigate the stealth infection angle.  If you have night sweats, hot flashes, you feel anxious and agitated a lot, you have a tendency towards loose stools, or you have body temperature regulation issues, you might want to investigate hyperthyroidism.  So of course, this depends on you are and what you’re dealing with.

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Is Being Underweight Actually a Problem?

The next question is, is being underweight actually a problem?  And that’s an important question because there are different reasons that people want to gain weight.  One is because they think that being underweight is unhealthy and they’re concerned about their longevity.  Another might just be aesthetic.  People might want to gain some weight for… vanity may not be the right word, but just to look –

Steve Wright:  People want to look good naked!

Chris Kresser:  Yeah, to feel confident in their appearance and look better, and those are both valid reasons.

According to the research, being slightly underweight is usually not associated with problems, but being significantly underweight is associated with issues, both increased morbidity, difficulty fighting disease, and increased mortality.  With weight, you see a U-shaped curve with mortality.  People who are really underweight have a higher risk of death, and people who are really overweight have a higher risk of death.  But the problem, in some ways, with this research is it’s very difficult to tease out causality.  When you see research showing that there’s an association between people who are underweight and a higher risk of death, how do we know that it’s being underweight that is causing the higher risk of death and not some condition that they have that’s causing them to be underweight that’s also causing the higher risk of death?  I suspect it’s more the latter, which goes back to what we were just talking about in terms of the importance of investigating these other underlying conditions.

In women, we often see really underweight women, especially those who are training hard, develop amenorrhea or dysmenorrhea, where they stop having a period.  They can develop infertility and a number of hormonal issues.  That’s probably the biggest thing that we see in women.  In men and women, you can see weak immune function and, as I said, difficulty fighting off disease and just a general lack of resilience and ability to thrive.  I’d say that’s probably the greatest risk.

Steve Wright:  I think it’s also kind of scary when you think about sarcopenia and aging and how you want to enter your latter years of life with as much muscle as you can.

Chris Kresser:  Muscle mass and bone density.  Exactly, yeah.  So that definitely can be a concern, and if it is, if you are significantly underweight, I think the chances of something else being present that is contributing to that are higher than if you’re just a little bit underweight.

OK, so now let’s get to the main event, which is how to gain weight on a paleo diet.

Steve Wright:  Drum roll…

Strategies for Gaining Weight on a Paleo Diet

Chris Kresser:  Yeah.  There are a few strategies here that we’re going to talk about, and in some ways, they’re just the reverse of how to lose weight on a paleo diet.  And then I’m going to talk about some other strategies that involve expanding your idea of what’s paleo and moving more to a paleo template than a strict paleo diet as it has been defined by some people.  That was partly my solution, which I’ll talk a little bit about.

I know a lot of people out there think calories have nothing to do with weight loss or weight gain.  I’m not one of those people.  I think if you want to gain weight, you need to be eating more calories in general, and I think you need to be eating liberally from all of the macronutrient groups.  Generally if you restrict one class of macronutrients, like carbohydrate or fat, you’re going to either maintain or lose weight because you’re really reducing the reward value of that diet.  You’re making it less likely that you’re going to overeat or be in a state of caloric excess, which you want to be in if you’re gaining weight, so I don’t recommend a low-carb diet or certainly not a low-fat diet for people who are trying to gain weight.  I recommend that you eat liberally from all of the macronutrient groups:  protein, fat, and carbohydrates.

In particular, I think skinny, lean people – and particularly guys – do well by really bumping up their starch intake.  I’ve noticed because I have everyone fill out a diet survey when they come to see me and they also tell me what kind of diet they’re following, a lot of people say, oh, I’m on a moderate-carbohydrate diet.  And when I look at what they’re eating, they have eggs and bacon and sauerkraut for breakfast.  Then they have meat and non-starchy vegetables for lunch, and then they have meat and a sweet potato and non-starchy vegetables for dinner and with maybe no fruit or one small serving of fruit.  And they think that that’s a moderate-carbohydrate diet.  Well, that’s actually a very low carbohydrate diet.  I don’t think that non-starchy vegetables make a significant contribution in terms of carbohydrate value because we expend a fair amount of energy in breaking down the cellulose and fiber in those vegetables and the net gain of glucose is very low in non-starchy vegetables, so I don’t even really count those.  And if someone’s just eating, like, a medium sweet potato, that’s maybe 25 or 30 grams of carbohydrates max.  Then they eat some blueberries or something.  That can be under 50 grams of carbohydrate.  And if someone is lean and has a fast metabolism, that’s a very low-carbohydrate diet.

Steve Wright:  What kind of total calories should somebody be trying to shoot for?

Chris Kresser:  Well, that depends on a number of factors like their lean body mass and their activity level, so it’s hard for me to give an exact amount.  But generally, going back to starch, I would say you should be eating a significant serving of starch with each meal.  So rather than the meal plan that I mentioned before, you’d have a big piece of starch with each meal, so a full potato or sweet potato, maybe even two small sweet potatoes, plantain.  Yuca is particularly dense and good for people who are trying to gain weight, taro root.  So you would have a major serving of starch with each meal.  On top of that, you would have maybe some fruit and additional carbohydrate in between meals if you can fit it in, and that could take the form of a smoothie, which we’ll come back to in a second, maybe taro chips cooked in duck fat.  When you have your starch, make sure that you’re adding fat to it.  Again, when we talk about weight loss, we talk about minimizing added fat, but when we talk about weight gain, you want to be having a significant amount of butter or coconut oil or whatever you tolerate together with your starch, and that will help you to gain weight.

I mentioned smoothies.  These can be really effective and helpful when you’re trying to gain weight, for the same reason that liquid calories are best avoided when you’re trying to lose weight.  Smoothies are not liquid calories in the way that a Coca-Cola is, but it’s still easier to eat more, as I’m sure everyone can attest, when you’re drinking it as a smoothie than it is to eat additional whole food.  One of my first blog posts several years ago, I think, was called Breakfast of Champions, and this included dairy, but it was my recipe for my morning smoothie that I had that was part of my weight gain efforts, and I think it was about 600 or 700 calories when I did the analysis in Nutrition Data.  And I was shooting for two of those smoothies a day, so that was almost an additional 1500 calories on top of the meals that I was eating and that’s significant.  That’s a big chunk of excess calories there to help gain weight.

So if you’re on a strict paleo diet, you can do coconut milk, maybe some coconut cream, avocado, almond milk, some banana, which is a higher-calorie fruit, higher carbohydrate load.  You can do some protein powder.  If you’re gaining weight, the PurePaleo that’s in my store now, which is the hydrolyzed beef protein, a lot of people who strength train swear by beef as a muscle-building substance, and that has both the glycine and the methionine in a good balance, so that’s a good choice.  Whey can be a good choice, too, if you tolerate it.  Then you can put some spinach and some green vegetables or something like that in there, maybe a little bit of cacao, fiber.  That can certainly be a few hundred calories depending on how big you have it, and as I said, if you do that a couple times a day, that can easily add an extra thousand calories to your routine.

Steve Wright:  I just want to share this thing from back in my strength training, bodybuilding days many, many years ago that a lot of people that I’ve talked with who are looking to gain weight really just don’t comprehend that this is like work, this is a job too, and it’s going to be a little uncomfortable when you get going.

Chris Kresser:  Yeah.

Steve Wright:  Bodybuilders, some of the top ones you see on stage – which nobody here is trying to look like that, but just for a reference point – these guys are consuming, like, 5000 to 9000 calories a day.  They’re just chugging this stuff, and it does not feel good for them.  It’s just part of their job.  It’s a conversation I had to have with Jordan a couple of times where, like, look, your stomach’s only so big, but for whatever your root causes are right now, 2500 calories isn’t doing it.  You have to get to 3500 or 4500.  Figure it out.  But it’s still work.

Chris Kresser:  Yeah.  And your stomach will generally expand and you’ll adapt somewhat to it, so it won’t be as hard as it is the first week when you’re doing that, and it does tend to get easier.  But you’re exactly right.  Weight loss is often work.  If you go on a protein-sparing modified fast where you’re only eating large amounts of protein and non-starchy vegetables and that’s it, basically a low-carb and low-fat diet, that’s not so easy!  It’s hard for people to stick with.  And weight gain efforts can be similarly difficult.  That’s a great point.

Speaking of weightlifting, Steve, that’s another super-important aspect of gaining weight.  Muscle weighs more than fat.  We’ve often heard this said.  And if you want to increase your weight, one of the best ways to do that is to increase your muscle mass, when you combine higher protein intake and higher overall calorie intake with a significant weightlifting program.  And generally if you’re lifting heavier weights, fewer repetitions might be better for weight gain efforts rather than if you’re trying to get more definition and lean out, you do higher reps and low weight.  Of course, there are a lot of schools of thought on this, but you want to be lifting weights regularly and doing this to increase your muscle mass and convert those extra calories and those extra protein calories into more muscle and more weight.  That’s super-important.  I think it’s really hard, actually, to gain weight just by eating if you’re lean without doing weightlifting.  That has definitely been my experience.

Steve Wright:  Yeah.  I think it’s really important for people to think about what their goal is here, and if the goal is really just to gain weight, improve health markers and what the mirror looks like, then lift heavy things two to three times a week and stay away from all the compound exercises and all the crazy programs out there because you’re trying to stay in the gym.  If you get hurt, then your weight gain efforts go down, and so you want to find some programs like, I think, Tim Ferriss and The 4-Hour Body have the Occam’s Protocol.  That seems to work really well for a lot of people.  Doug McGuff has a bunch of good programs.

Chris Kresser:  Starting Strength is a really great Olympic weightlifting program.  There are some good ones out there.  Make sure that’s part of your routine if you’re trying to gain weight.

Now, so far we’ve been talking about how to gain weight on a strict paleo type of diet, but there are some other options.  If you tolerate dairy, for example, I’ve found that dairy is really helpful for maintaining and even gaining weight.  Early on when I was doing paleo – I didn’t even know it was called paleo at that point, but I had sort of discovered it – and I stopped consuming dairy products, it was very hard for me to put on weight.  And when I added back things like cream and butter and whole milk kefir that I make at home and then even raw fluid milk, it was much easier for me to keep weight on.  So if you tolerate dairy, if you’ve removed it from your diet for at least 30 days and added it back in and you don’t have any issues and you’ve been tested and you don’t have casein intolerance or lactose intolerance, then I think dairy can be really helpful for weight gain.  Speaking about bodybuilders, there are definitely a lot of bodybuilders out there who drink milk like it’s going out of style.

Steve Wright:  Yeah.

Chris Kresser:  Because, again, when you’re trying to add calories, fluid calories, especially when it’s nutrient dense like milk – full-fat milk I’m talking about, not low-fat or non-fat milk – that can be a really big ally and really helpful in terms of muscle building.

Steve Wright:  If you want to expand your horizons, go Google “GOMAD.”  It’s a bodybuilding idea of a gallon of milk a day.

Chris Kresser:  There you go!

Steve Wright:  You’ll see a bunch of before-and-after pics of these guys adding a ton of mass, which is what we’re talking about here.

Chris Kresser:  Yeah, exactly.  So there’s that, and then you might even consider some non-paleo carbohydrate sources.  White rice, for example, can be a way to pack on some extra starch, and some people find that it helps more with gain than some of the other starches that I mentioned before like sweet potatoes, plantains, etc.

Before we finish, I want to tell a story about one of my patients that had a pretty miraculous transformation in terms of her weight and even body composition.  She had been sick for a long time, was really thin and underweight, and she ended up getting a fecal microbiota transplant, a stool transplant.  When I saw her a few months after she had done this, she looked like a different person.  Her facial structure had completely changed.  She had much more of a round face.  It almost seemed like wider dental arches, and her whole face looked different.  She said that she had developed breasts, where she hadn’t had breasts for a long time.  She really just started to fill out, and her body composition and body type actually did change, and that was just from a fecal transplant, which completely, of course, restored her beneficial gut bacteria.

Now, on the other hand, I’ve seen people who have lost weight after doing a fecal transplant, who have been 10 or 15 pounds overweight, they’ve done a transplant, and that weight has effortlessly come off even without making any dietary changes.  So it’s just another testament to how important the gut flora is to our overall health.  If the gut flora is predisposing us to being underweight and we fix it, we’ll probably gain weight.  And if the gut flora is predisposing us to being overweight and we fix it, we’ll probably lose weight.  There is at least some anecdotal evidence there that changing the gut can not only change our weight, but even our body type at least to some degree.

Steve Wright:  Are there any supplements before we wrap up here, Chris?  Because I know, for instance, creatine monohydrate has been extensively studied and seems to really be a cheap and easy thing to add into this sort of a program that might help with the weight gain.

Chris Kresser:  Yeah, that’s a great point, Steve.  Creatine has been well studied.  It’s pretty safe and pretty effective, so that’s something you can definitely do.  Protein powder I would consider also to be a supplement, not a normal part of the diet, and that’s good.  Fermented cod liver oil, the fat-soluble vitamins are important, too.  But I don’t typically tend to go to supplements other than those for weight gain as a first line of effort.  I’m more focused on why they’re not gaining weight and addressing those mechanisms and then all the dietary stuff that we talked about.

So, Robert, I hope this is helpful.  I hope it’s helpful for all the other lean, fast metabolism people out there who don’t get enough love from the paleo community, and we’ll be back next week!

Steve Wright:  Yeah, thanks, everyone.  If you want more info about what Chris is researching in between podcasts, the studies he’s looking at, go to Facebook.com/ChrisKresserLAc and Twitter.com/ChrisKresser.

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Join the conversation

  1. GREAT ARTICLE, chris! my BMI has always been either underweight (during active flares of UC) or on the low end of “normal”, 21.5 right now, but i know i feel healthier when i’m heavier, and those are the hardest pounds to tack on.

    i suspect i have yeast overgrowth from years of antibiotic use, including cipro and levaquin. this means starch tends to create problems in my gut, such as ulcerative colitis, which recent studies suggest has a fungal (allergic) trigger.

    i also suspect chronic inflammation/stress may be impairing my vagal nerve function.


    what do you recommend for us, besides a total gut flora remodeling (FMT) to tolerate more carbs in our diets? thanks!

  2. My husband has been trying to gain weight for most of his life. He suffers from multiple autoimmune disorders, and spent his childhood taking rounds of antibiotics…and despite every dietary variation he’s tried thus far (SAD, vegetarian, vegetarian-with-lots-of-sugar, high-fat GAPS, higher-starch paleo, higher-fat paleo)…he does NOT gain weight. He has forced himself to eat more than he wants, and even this does not add up to a single ounce of weight gain.

    The only thing that ever made a difference was a six-week “milk cure” that he did in 2011. For those six weeks, he ate/drank nothing besides 1.5 gallons of raw milk per day. Three weeks in, he started feeling tingly around the middle. By the end of six weeks, he had gained fifteen pounds, and was absolutely ecstatic!

    The pounds came off immediately, as soon as he stopped the milk cure. Ever since, I have joked with him (to the point where he is tired of this joke, I can assure you) that I want to get fecal transplants for our whole family! I feel sure that in some (many?) respect, underweight is the metabolic flip side of obesity, and the usual dietary triggers have certainly not been successful in helping my husband to kickstart his metabolism.

    This is my question: where in this country can one get a fecal transplant?? (_Are_ there any clinics that will allow someone to get a FT if they don’t have a life-threatening gastrointestinal infection?)


    • Hello Sarabeth

      When your husband followed the milk diet, did he spend all that time lying in bed as the diet calls for?

      Did he experience firm bowel movements?


  3. 3500-4500 calories. sounds like a big lot of tasty paleo food 🙂 BUT: I recall reading some mouse experiment that restricting calories prolongs life. Now, I am not a mouse, but I think humans tried it too 🙂 They even found the biological mechanism how this effect works. So, if we turn it around, wouldn’t eating 3500-4500 calories shorten life? And cause some small decrease in health? So, isn’t it healthier to get a gut flora which does the job of letting one gain a healthy amount of weight (fecal transplant, as in your example)?

    I could imagine that the gut flora transplantation is the healthier option… Or did our ancestors eat 3500-4500 calories? And does any tribe living today, eating largely paleo food, eat that much? And, if those good bacteria received by the fecal transplant digest a bigger part of what you could not digest (resistant starch, etc) then the products of their metabolism (butyrate, etc) are certainly good for you. Opposed to this, if that does not happen, who will use that energy in the end? Some bad bacteria or fungi? Nobody? Which type of gut flora do currently living paleo tribes typically have: the one that helps the human host to gain more energy out of the same food or the one that let’s one gain less?

    To put it simple, my guess would be that the fecal transplant could be the healthier (and on the long run cheaper) option, involving also less “work” of eating as you put it. 🙂

    Chris, what would be your take on this?

    Thanks a big lot for your great work!!!

  4. Gid rid of all of your parasites, bacteria and viruses that depleting body of callories, vitamins, minerals and etc..all the good stuff. Did you know that all your leaky guts , hormone disbalance and other modern “syndromes’ -All come from parasites? Did you know that every person out of 2 has parasites in America today?!? Sadly, modern medicines are very little trained about parasites, thus, doctors dont recognize/talk/treat the negative side of having parasites in their patients. Do more research on parasites. Kill them first before you rely on any diets.

    • No, Svetlana. There are healthy and unhealthy gut bacteria and we must not eliminate them all; they are not all ‘parasites’. I’m sure Chris’s literature and other people’s will give you sufficient information without there necessarily being further research.

  5. Chris,
    I’d like to experiment and see if I have a gut issue with food absorption due to small intestine bacterial overgrowth. What foods will help eliminate the problem? What about Kefir? Yogurt? Carrot salad with apple vinegar and coconut oil?

  6. Great post, with plenty of interesting ideas – and very timely. One thing you didn’t cover in the analysis of possible causes is the timing of being underweight. For example, I have lost 25 lbs from being on Paleo, and more particularly the AIP protocol. I’m just starting to get concerned that I’m still losing weight, not least when I’m now happy with my weight and have bought a new wardrobe! The immediate cause of weight loss was clearly diet. That said, I’m now back to the weight I was when I left University, 30 years ago – so my historical weight gain was also fairly clearly diet and alcohol. I feel great, with brain fog lifted, but I’m always hungry and occasionally I’m short on energy for cycling etc, plus I have mild auto-immune symptoms like hay-fever, eczema on my feet, and bags under my eyes on waking. My primary action after reading the post will be to try out starches again, which I eliminated (along with eggs, nuts, seeds etc, all of which I’ll slowly re-introduce). I’m intolerant to gluten and highly intolerant to dairy, so I won’t touch those. My only question is whether I should also be testing for adrenal problems, thyroid problems and/or SIBO?

  7. Hi Chris! 1000x thanks for answering my question with this podcast!!! This was really the info I was looking for!

  8. Great show.

    One thing to note is that Starting Strength is not an Olympic weightlifting program (Clean and Jerk, Snatch), but rather a barbell training program closer to powerlifting focusing on Squat, Power Clean, Deadlift, Bench press and overhead press. It is a great program and much simpler than an Olympic Lifting program.

  9. Chris. Please can you recommend a methology for testing with the types if tests. For example, start with thyroid and if that is normal then go to leaky gut and SIBO and then HP and then… Or should I just shot-gun it and have all tests done?
    I know Metametrix (?) have good tests. Where to go for the others?
    And do you have reference ranges for thyroid please. This is confusing for me.

  10. i’m 6ft 1 in tall and have weighed between 135-145 ever since highschool to present day (last 12 years). i seem i can’t get over the 145lb hump. i have hashimoto’s and pretty bad adrenal problems so i know there needs to be fixing in that area, i also have digestive issues since as about 5 yrs ago and was told i have leaky gut and candida overgrowth. i understand i have to fix these problems and i have improved the digestive part over the last few years but i want to gain weight NOW. being skinny and bones with little muscle mass is not good to look at and for self confidence. . and definitely not sending the females in my direction, ha. having leaky gut and food sensivities, would it be ok to increase things like rice, quinoa, chips and other high carbs along with strength training, creatine and whey protein??! i know the other things need fixed but those can take years and i want to gain right now!

    • You could try the GAPS diet, with rutabega and turnips and beets as the starches. And bone broth soups with egg yolks. And butter, grass-fed pork fat, and coconut in all forms. See the GAPS book for a discussion of grains, which can feed bad bacteria.

  11. Thanks for this! I am been slim all my life and putting on muscle eating a 80/20 paleo diet has been difficult. I will definitely start drinking more milk and adding back some smart starches.

  12. This is a fine post. It speaks exactly to my issues, which I’ve had trouble addressing on my Paleo diet. Mark Sisson has written a bit on how to gain weight while eating Paleo/Primal, but your analysis is much more thorough. If you recall, Loren Cordain’s publisher began the Paleo wave by selling the diet as a foolproof way to lose weight. And indeed, it often is. But for me, the elimination of grains, beans and dairy, which has improved my health a lot since I have numerous food sensitivities, has also made it difficult for me to not only gain weight but keep it on.

    The gut and hormonal issues that you mention seem to be the root cause for me. On your advice I’m now working with a functional medicine physician. I feel hopeful that I can improve my sub-par level of health. As a 62 year-old woman, it’s crucial to do this now, because I don’t want to spend my old age in a wheelchair!

    Thanks too for the suggestions on what carbs to eat to gain weight…although I understand that until I address the underlying dysfunctions my results won’t be optimal. But I have patience, and faith in the methodology of functional medicine. It makes so much sense.

    Thank you very much.

  13. Thank you so much for this, Chris! I haven’t had a chance to listen carefully yet, but I struggle with this. I am a runner (something I get stick for from some Paleo folks…) and somewhat naturally lean. Switching to Paleo undoubtedly made me healthier. But I also lost 25 pounds and was on my way to losing more. I have been experimenting with how to at least maintain my weight without grains & sugars. I’ve added back yogurt, but am looking forward to some other tips for staying clean and keeping weight in. Thank you, thank you!

    • I should have said, too, that part of the problem is how to gain weight in a way that is _affordable_. I’d be happy to eat twice as much steak, but the grocery budget isn’t that deep…

  14. Great discussion. I’ve been extremely underweight before and I find it’s hard to find helpful info from a paleo perspective.
    have a nice day.

  15. I’ve got a friend who is ‘skinny’, on a paleo diet and complains she can’t put on weight. Did I mention she skips meals, under eats, over exercises, avoids carbs because of paranoia about candida, and is also in denial about her history of eating disorders?. Men slip into eating disorders too, lets not forgot them, it’s not talked about much though. Men tend to hide behind ‘training’ or being a jogger to cover up their illness.

  16. Great discussion. I’ve been extremely underweight before and I find it’s hard to find helpful info from a paleo perspective. For a while I had to give my chronic gut issues the back seat and focus on gaining weight, which was unpleasant but necessary.

  17. OMG, finally somebody talking and caring about the rest of us who do not belong to the obese population but have other weight struggles. It isn’t enough that we can’t find clothes or underwear at the store because everything is oversized but every single health expert out there is always focusing on obesity and there is nothing for the rest of us. It is a very lonely world out there for those of us who are leaner. Thanks Chris!

  18. Having Crohn’s disease, I was a bit underweight most of my life. The muscle I would pack in a few months, I could lose it quickly in a few weeks if I stopped working out or if I was sick. After a year and a half on a paleo diet, my crohn’s was much better, but I was still underweight. I seem to gain muscle mass more easily, but I wanted a big more fat. I tried going ketogenic for a while during winter. It was really hard maintaining weight at that time (but you do feel awesome).

    Adding a bowl of rice a day did the trick. I quickly gained 10 pounds (now at 155 lbs) after starting eating parboiled rice (I jampack it with turmeric and other spices). My face looks healthier now. I restricted carbs for a while, but end up having the typical symptoms of long term carb restriction. I can eat fruits, veggies and salads, but not in huge quantity. While reading on parboiled rice, I also took interest in resistant starch. I now do the potato starch hack and it’s awesome (best sleep ever in combination with magnesium).