Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
23 Oct

Starch: Fallback Food or Essential Nutrient?


I’ve always said that carbs aren’t bad in and of themselves. They’re better in certain contexts and worse in others.

Are you CrossFitting five days a week? Training for the Olympics? Breastfeeding? These are contexts in which carbs are warranted, helpful, and even healthy.

Are you insulin-resistant and hyperinsulinemic? Are you a moderately active person with a few extra pounds? Are you diabetic, or nearly so? These are contexts in which a low carb intake would be warranted, helpful, and even healthy.

With my Carb Curve, I’ve tried to establish a basic framework that works for most people who come to this site looking to get healthy. I think I’ve mostly succeeded. 150 grams of carbohydrates from fruit, squashes, roots, and tubers is more than enough for the vast majority of people to feel sated, healthy, and energetic without leading to weight gain or exacerbating metabolic syndrome. Add more if you need it to fuel your training; remove some if you’re particularly sedentary, diabetic, or looking to lose weight; try a carb refeed every few days of 200-300 grams if you’re very low carb or ketogenic. Round that out with all the non-starchy vegetables you want and you’re looking at a very diverse diet rich with phytonutrients, vitamins and minerals with lots of room for nutrient-dense meat and fat sources. Not bad, right? Pretty simple, and the results speak for themselves.

Despite that, there’s an undercurrent that high-carb Primal and low-carb Primal are interchangeable. That macronutrient ratios don’t matter regardless of health status or metabolic context, and that we evolved eating a diet rich in, if not based on, starchy tubers.

Today, I’m going to address some of the most common arguments for these claims. I’m not arguing against including starch in your diet, now. I’m arguing against this notion that inclusion of large amounts of starch is the defining characteristic of an ancestral diet.

Let’s jump right in…

But Grok Ate Tubers, and Lots of ’em!

This is a common refrain. And sure, wild tubers, AKA underground storage organs, have been around longer than we have. They’re an important food source for many animals, including primates, so it’s no wonder early humans utilized wild tubers. But before you rush out and buy potato futures, consider a few points:

Wild tubers are not Russet potatoes. They generally don’t turn into creamy smooth starchy goodness when baked. They’re tough, fibrous things that provide a fraction of the usable energy modern cultivars provide (PDF). Whereas your typical kilogram of potato offers over 1000 calories, a kilo of many wild tuber varieties hover at around 300 calories. Eating these would have provided a moderate dose of glucose – akin to, perhaps, butternut squash – plus a load of prebiotic fiber for the gut flora. In addition to fiber, wild tubers are extremely rich in minerals, with some varieties offering over 500 mg of calcium per 100 grams of tuber – so they’re also more mineral-dense than the tubers most of us can buy at the store.

They were very likely fallback foods. Among the Hadza people of Tanzania, tubers are the least-preferred food source. If you could see the aftermath of a tuber feast, you’d understand why: piles and piles of chewed up fiber, spit out after sucking all the caloric glucose-rich starch from the tubers. It gets the job done, but it’s not very pleasant or appetizing. Now, before you point to the fact that tubers were also the most-available food source, consider that the environment of the Hadza is not the environment of early man. The geography may be the same, but everything else has changed. Like most all other extant hunter-gatherers, they are the remaining members of people who have been driven off the best, most resource-rich lands into the margins, those scrubby relatively resource-poor lands. They’ve literally been marginalized. They eat lots of tubers because they are widely available and they eat less meat and honey because they aren’t always available (even though they prefer the latter two). Before agriculture and the rise of the state, land was sparsely populated by humans and rich in game. Animals were simply more numerous and thus easier to come by. I’m not saying that our ancestors were carnivores – quite the contrary, in fact – but all else being equal hunter-gatherers on game-rich lands will have more opportunities to consume (the preferred) animals and less cause to fallback on fibrous tubers than hunter-gatherers on marginalized lands.

Specific genetic adaptations to tuber-based diets emerged only recently. Adaptations include detoxification of glycosides (potentially toxic substances found in tubers), enhancement of folate biosynthesis (tubers contain little folate, so people subsisting on tubers would need to develop ways to make enough of their own in-house), and improvements in starch metabolism. If we’d been eating a tuber-rich diet for our entire history as humans, why would these recent genetic adaptations even be necessary?

But We Make Salivary Amylase!

Salivary amylase is like pancreatic amylase in that it digests starch into simple, absorbable sugars, only in your mouth. It helps prepare starch for further digestion, particularly the more you chew. Plus, your amylase-rich saliva gets swallowed and continues working on the starch throughout digestion. Compared to the fruit-eating and starch-eschewing chimpanzee with two copies, humans have between two and fifteen copies of the salivary amylase gene. Some have posited that this indicates a necessary role for starch in human nutrition. It sounds like a reasonable argument.

As I’ve mentioned before, though, having a high number of salivary amylase gene copies isn’t universal. It depends on your background. If your ancestors ate a lot of starch, you’re more likely to have more copies than the people whose ancestors did not eat as much. Beyond the first copies around 200 thousand years ago, researchers are still piecing together exactly when the extra copies of salivary amylase genes were added to (some segments of) the human genome, but judging from the emergence of other recent, tuber-specific adaptations (mentioned above), it wasn’t too long ago for many of us.

And if you are one of the high-amylase individuals, remember why salivary amylase is ultimately there: to assist in the digestion (and thus assimilation) of dietary starch. It’s not there to justify overconsumption of starchy tubers whose carbs you don’t really need. High copies of salivary amylase genes are only helpful if you need the glucose to survive. If you need the calories, if you’ll use the calories, then the salivary amylase will help you do it. But if you’re a mostly sedentary modern computer-using human who works out moderately and drives to work, I wonder whether you truly need so much starch.

Which brings me to the next argument.

But People Didn’t Start Getting Fat en Masse Until the Advent of Industrial Foods; Most Starch-Eating Agriculturalists Were Actually Pretty Thin!

This is true. You can look at old pictures from the turn of the last century and you’ll notice that most everyone is slim. If you could travel back through time and space to visit and view Mayan empire, the Indus valley civilizations, the Roman republic, the signing of the Magna Carta, the first farmers in the fertile crescent – you would bring back photos of mostly lean people as well. Lean, often perpetually exhausted and overworked people.

Agriculture introduced the concept of “labor.” People living in agricultural societies had to work hard to survive. Rather than draw on the seemingly endless bounty of nature, agriculturalists imposed themselves on the land and struggled against the very laws of nature to force crops to grow. They worked long hours and performed tons of “reps.” It’s been estimated that medieval peasants, for example, had to consume up to twice as many calories as modern humans just to keep up with the demands of their daily labor. They certainly weren’t fat on their high-calorie, high-carb diets because they were “earning” their carbs with loads of glucose-demanding physical work. If you’re not doing the work of a medieval serf, you won’t have the same tolerance of and need for starch.

I’m not suggesting hunter-gatherers didn’t work or physically exert themselves, by the way. Hunter-gatherers worked, for sure, just not the kind of daily, miserable, physically-exhausting toil you’d do as a farmer. Maybe three to five hours a day. It wasn’t day in, day out, either; a successful hunt was followed by days of relaxing, partying, and feasting. It was more fractal, varied, random, seasonal.

Thin doesn’t always equal healthy, anyway. Remember: I stayed thin and “fit” on 750-1000 grams of carbs every day when I was running 100 miles a week. Doesn’t mean it was a good idea or I wasn’t hurting myself.

But the Kitavans Ate a Starch-Based Diet and Were Healthy!

I’ve touched on the Kitavans before, and I largely agree. They were healthy. Here’s the thing, though: most people aren’t raised in a pristine South Pacific island environment replete with sunshine (vitamin D), crystal clear waters, coconuts, biologically congruent sleep patterns, extended families and strong communities, and extended breastfeeding with a near absence of gluten-containing grains and processed seed oils (that last one could be said for the medieval serfs and other pre-industrial starch eaters, too!). They’re very active and although they consume relatively low amounts of fat, what fat they do consume is derived from coconuts (saturated fats) and fish (omega-3s). Not to mention the epigenetic advantages of having parents and grandparents who lived this way. There’s far more to the Kitavan way of life than all the tubers they eat.

If you hope to have the same results eating a potato-based diet, you better get all the lifestyle and other dietary factors right (plus figure out how to travel back in time to influence the way your parents and grandparents lived and ate!).

As an insular island people, the Kitavans may also have genetic component to their tolerance of a high-carb diet, similar to the proposed adaptations related to gluconeogenesis that allow Arctic natives to flourish on a very low carb diet nearly bereft of significant plant input. If you don’t have those same island genetics, you may not have the same response to the Kitavan diet. Give it a shot, though; you could do a whole lot worse!

Anyway – those are the arguments I’m seeing. They’re interesting but ultimately limited and short-sighted in my opinion. My goal is not to attack or dismiss them (or dietary starch), but rather to offer some nuances to consider before integrating them into the Primal framework.

What do you think, folks? What other arguments are out there? What have you experienced with starch?

Let me know below, and thanks for reading!

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. I read a lot of fitness blogs that promote paleo, and I cannot for the life of me see how people are hitting 100 plus carbs per day only eating vegetables and some fruit. Even adding some coconut flour and small amounts of almonds puts me around 70 on most days. I think you need tubers just to get into the carb level that your body needs especially if you have some sort of movement protocol that your following.

    Jamie wrote on October 23rd, 2013
  2. I dropped to very low carbs, only from leafy veg and the odd nut. My already slim frame became a bit boney. I also started having painful periods and PMS. These stopped once I started eating rice, kumera and fruit again. I also had to stop my IF, which I enjoyed. I will try IF again, but maybe with more carbs before and after.

    Rebecca wrote on October 23rd, 2013
  3. I have Ankylosing Spondylitis which is a form of Arthritis of the spine. I suffered for 12 long years with it not knowing why sometimes it was more intense than at others times. I have been on a daily dose of anti inflammatories for 12 years but even they sometimes cannot stop the inflammation and restricted movement that results. At times I could not sleep due to the pain, could not walk, could not even sit comfortably. Everything was hard work. Until I discovered a website which promoted eliminating STARCH from my diet. No Rheumatologist will prescribe this, instead they want me to take very expensive biologic drug injections. I refused the injections, and eliminated starch from my diet. The improvements came very quickly. Even the starch in a seemingly benign vegetable like Zucchini can set off a bout of inflammation. Grains & Potatoes…..the worst.

    Starch to me is poison.

    The theory is that starch does not digest in the body very well, a certain common type of bacteria grow on the undigested starch (Klebsiella), which multiplies and the body produces an auto immune response to keep the bacteria under control. Unfortunately I have a gene (HLA-B27) that looks similar to the Klebsiella bacteria, so my immune attacks my good cells in a case of mistaken identify. That is the scientifically unproven theory, but there is no doubt removal of starch from the diet, therefore removing the food source of the bacteria, reduces the inflammation for me. The difference is massive. It makes me wonder how many other people suffer differing problems due to starch in the diet.

    More can be read about it here.

    Darren wrote on October 23rd, 2013
  4. I think this is great advice to get someone on a healthy track. Thank you for not only pointing out the benefits of a diet such as this but also pinpoint the kind of people that might benefit from a diet like this.

    Ryan Byars wrote on October 23rd, 2013
  5. “a kilo of many wild tuber varieties hover at around 300 calories”. Just what is and isn’t considered a wild tuber here? Cassava (tapioca) root is like 6000 calories per kilogram, over twice that of potatoes (3000)…

    Brad wrote on October 23rd, 2013
    • Well, cassava is derived from a wild progenitor native to South America, where it was domesticated around 10k BC. It was brought to Africa in the 16th century, where it quickly replaced traditional starch crops. That would indicate that the wild starches Africans were using weren’t as calorically dense as the newcomer, because why else would they switch? It also indicates that the primary site of human evolution – Africa – may never have had anything as starchy as the cassava (why not just keep using what they’d been using?). Heck, cassava is huge everywhere, even Asia. It’s the most popular tuber worldwide. It might not be the best model for ancestral tuber consumption.

      Worker Bee 2 wrote on October 23rd, 2013
  6. I wish this was written before I started researching paleo/low carb. Most fear fat, I fear carbs now and it’s damaged my hormones. Only being 22, after months of reading blogs and personal stories… Carbs were the probably. Should have ate a lot more! I am now thankfully!
    Great post! Carbs are definitely important!!

    Chelsea wrote on October 23rd, 2013
  7. Look at the South Pacific Islanders. From Palau to Hawaii, you find some big people (and I don’t mean big boned), even in historical accounts. Their diets are heavy heavy on tubers, taro in particular; this isn’t caused by McDonalds.

    Islander wrote on October 23rd, 2013
  8. anyone know if the carb curve is talking net carbs? total carbs?

    dino wrote on October 23rd, 2013
  9. For the last year I have almost fully ignored the amount of carbs I was eating as long as they were coming from starchy tubers or squashes. I would also limit fruit to about 1 piece/day. I would estimate about 150-200g per day. I had been on lower carb paleo/primal for about a year before that.

    What I found after including more starch was actually an improvement in my body composition. Not a huge improvement, but then again I didn’t have all that much to improve there anyway. I didn’t notice any changes in digestive health, performance, mood, or seasonal allergy symptoms. So, I figured I would continue with this since I really like sweet potatoes and plantains; plus, the perfect health diet and Chris Kresser aren’t really on board with really low carb if you are metabolically healthy (ie. no obesity or diabetes).

    However, I have just started to read Grain Brain, and I am starting to re-think the amount of carbs I am eating. I feel like as I progress through the book I will start to decrease my carb intake below 100g per day and see what happens.

    Andy wrote on October 23rd, 2013
    • @Andy, you realize that 200g of carbs is an entire kilogram of sweet potatoes (they are 20g carbs per 100g uncooked). That would mean 3,600 calories of only sweet potatoes. I doubt seriously that you are eating that much. So maybe you are talking 200g of sweet potatoes and not 200g of carbs?

      Brad wrote on October 23rd, 2013
  10. As an aside to the actual information in the article, can I just say I love the fact that you have used the diet of the Hadza people as a source of information? I taught in Tanzania for 4 years and had the opportunity to spend time with my students visiting with the Hadza, watching the men hunt and the women collect honey. Such a fascinating culture that is quickly being lost! I’m so appreciative of anyone who is aware of them.

    Michele wrote on October 23rd, 2013
  11. Cassava root has twice the calories of potatoes. Just sayin’.

    Brad wrote on October 23rd, 2013
  12. Touching on the point about the Kitavans, our ancestors would have developed digestive tracts and nutritional requirements to suit the environment around them. This is why people who live in the far north (Innuits etc) ate so much game (because plants didn’t grow in the extended winter and large animals were available). Those who lived in more tropical regions had an abundance of plant foods (fruits and tubers) and smaller game (monkeys, tapirs, fish), and so their requirements for health changed accordingly.

    The same goes for modern humans – there is no fixed amount of macro-nutrients that can be applied across the board, it is up to the individual to experiment and find their perfect ratios of protein, fat and carbohydrate.

    Try for more on metabolic typing.

    Barnaby Nichols wrote on October 23rd, 2013
  13. I eat a lot of veggies and some fruit and no bread, pasta, pastries, etc and I’m on a 16/8 IF schedule. I am 5’8″ tall and weigh about 142 pounds. I do eat some brown rice and quinoa here and there. My diet is pretty clean, controlling stress and getting enough sleep is my big problem / challenge. Best wishes to everyone on achieving your health goals.

    George wrote on October 23rd, 2013
  14. I was fascinated when reading to my children about Lewis and Clark to see that Sacagawea told L&C that she would rather camp in a certain spot where she knew she wouldn’t have to resort to eating tubers.

    Mamagrok wrote on October 23rd, 2013
  15. Great post, I was tempted by tubers but now I’m gonna leave them for the time being. Love the fact you clear up the misconception of paleo and low carbs – thanks :)

    Nadine wrote on October 23rd, 2013
  16. Great article. Mark I do wish you would have more posts about differences in dietary needs between men and women on paleo/primal diets. I saw a lot of comments on here about women in their 40s who found that adding back in some starchy vegetables after being on a low carb diet for awhile was very helpful. I am of a similar age (though can’t say I am in “perimenopause” and don’t know how I would know such a thing), and also feel this may be true for me (the need for periods of eating more starchy veggies), though I have not yet quite found the amount that works well for me. I also read something Paul Jaminet wrote about how very low carb diets can wreak havoc on your mucous membranes. I am not sure if this is true or not but recently I started having a lot of dryness of the mouth (as well as in other areas of my body) and wondered if I had gone too low carb. Drinking loads of water and upping my intake of starchy veggies seems perhaps to have helped. But can anybody out there clear up the issue of carb intake and compromising your mucous membranes? Is this a concern?? Would love more details on this. Mark maybe a post about this would be helpful.

    Alma Mahler wrote on October 23rd, 2013
    • This is JME, but I was very low carb for well over a year and never had any mucous membrane drying. OTOH, just months after I increased my natural carb intake dramatically, I experienced drying in every mucous membrane in my body, and I cannot seem to reverse the effects, months later.

      Mamagrok wrote on October 24th, 2013
  17. How are we delineating between “starch” and carbohydrates as a whole? For example, there are plenty of carbs in other sources such as fruit, honey, and greens like broccoli, but would those fall in this starch category? As a hard charging athlete, I have quite a good amount of carbohydrates in my diet (as I count carbs from all sources), but it’s not all coming from tubers.

    Chuck wrote on October 24th, 2013
    • There is no starch is Brocolli or if there is, very small amounts. I eat a lot of Brocolli as it is one of the few starchless vegetables I can eat. You can use Iodine to test for starch. I use a weaker Iodine tincture of some sort. Put a drop on your food (dont’ eat it, its poison) and if it goes dark/black it contains starch. Put a drop on white bread, it goes black instantly. Vegetables and fruits can vary in starch content throughout the year as well. Avocados for example become starchy when cool stored. Apples are starchy when they are fresh and crisp I notice.

      Darren wrote on October 24th, 2013
      • Thanks Darren

        Chuck wrote on October 25th, 2013
  18. I had a discussion with a good friend of mine a couple of months ago along the lines of the article above. He argued that he’d lost weight eating a standard diet having, that evening prior to my arrival, vomited twice, and afterward during my visit, worked his way through the best part of a box of tissues for a continually runny nose. I apologized to him that I hadn’t explained my reasons for the primal diet clearly to him. Those reasons were; that I ate this way because of the health benefits, that weight loss was a side benefit (Although a damn good one) and it provided optimul support for my immune system. I went on to explain that I wasn’t the one currently sat on the sofa looking like death warmed up. He proceeded to say “you’ll catch this, wait and see”. I said to him “let’s carry out an experiment, hand me the cup you’ve just drunk from” he did and I drank from the same cup. I said “cough over me” he said “you’re mad!”, I said “that may be so, just cough over me and make it a real hacker”! He did then he sneezed, unintentionally I hasten to add, so I breathed in deepy.

    The bet we made was for a £5.00 and a week later I went to collect at which point he said “no no it took a couple of weeks for it to gestate as I caught this bug from my mother (a heavy smoker with emphysema). I replied that I was happy to go for as long as he wished and a further two weeks later… I pocketed five quid.

    Now it could be said that it was pure chance I didn’t catch whatever it was he was suffering from but all of us in the primal/paleo community know why I didn’t and don’t/rarely get ill. Finishing the discussion with him on that evening he pointed out that from my “sample of one” I was hardly proof that the diet worked. I ended it with the point that the paleo community has many thousands if not hundreds of thousands of “samples” (not to mention indiginous communties eating this way worlwide) to show it works and that I had tried it from his side of the fence but he had not from mine. Therefore how was he qualified to put forward a logical argument as to whether it would benefit him or not.

    Mark keep up the good work this website and all that it stands for is a shining light in a world full of crap. To the primal/paleo community, love to you all and my hope goes out to those whom have yet to discover what it is to be truly healthy.

    Gary wrote on October 24th, 2013
    • Dr. Joel Fuhrman, a “nutrarian”, notes his diet is so rich in nutrients critical to heath that few of his patients and adherents to his eating plan catch colds.

      Also, Dr. Fuhrman has objective evidence of the reversal of heart disease*, reducing cancer, eliminating Type 2 diabetes and inflammatory disease.

      His diet?

      – Vegetables
      – Nuts
      – Legumes
      – Small amounts of fruit
      – Very small amounts of animal protein

      *There’s a also objective research “starch” based diets will do the same.

      Ed wrote on October 25th, 2013
  19. Mark, I really wish you would’ve addressed women’s cycles and necessary starch for menstruation. So many women lose their cycles only eating berries and salads. I know I did. Add back in a sweet potato, some bananas, and yes even some white potatoes and white rice. BAM! Flow city. 😉

    Ashley wrote on October 24th, 2013
    • Yes! This is so true! I am back on the “starch road” because I lost my cycle by only eating non-starchy vegetables and the occasional piece of fruit (carb-wise). I was eating high fat (50-60% of my macros), which I thought was enough to keep “flow city” going… I am hoping including more starchy carbs (so far just squash and sweet potatoes) will help. Please, Mark, do a post on this!

      K wrote on October 25th, 2013
  20. Brilliant post, Mark. Thank you for lucidly quashing some of these myths. Evolutionary anthropology and the archaeological record palpably demonstrate the stark paucity of tubers present in the environment; stable nitrogen isotope data demonstrates their near-absence from our diet for almost all of our evolutionary history. I’ve been trying to argue this point for quite some time :)

    Anna / Lifextension wrote on October 24th, 2013
  21. I would like to see a detailed breakdown of the metabolism of fat vs metabolism of carbs. I understand that carbs result in release of insulin, but doesn’t dietary fat become stored as adipose tissue and therefore induce a higher insulin release that way?

    Dan wrote on October 24th, 2013
  22. Great article Mark. Most paleo bloggers are more concerned with defending their dogma than just seeing things as they are, so thanks for being such a voice of reason.

    Robin H wrote on October 25th, 2013
  23. All I know is that a 1.5 years ago I tried an experiment.
    I had cut down carbs to almost 0 for 6 straight months. After that I started carbs back up and it resulted in a massive weight gain that to this day I still can’t get rid of….primal diet or not.

    Don’t cut carbs if your body is used to burning it your entire life and you have no weight issues from it…big mistake I regret.

    Issabeau wrote on October 26th, 2013
  24. I’ve noticed when I increase my starch intake, i begin to either put on the pounds, or i find it harder to loose weight. The weight gain is very slow, but noticeable. I begin to look a little ‘thicker’. I love potatoes! But i know i need to just ‘let them go’ :)

    Stacy S wrote on October 28th, 2013
  25. Quick question: you mentioned if you are physically working out more than the average person, more starchy carb would be better: however, what would reccomend eating more of if you were doing an increased level of intense studying? Just an increase in calories in general or adding more starchy carbs if the brain requires 20g to survive or perform.

    Charleh Dickinson wrote on October 29th, 2013
  26. I’ve cut carbs for 10 days only, and the results was amazing!!!

    Griselda wrote on October 30th, 2013
  27. Mark, what do you think of the Specific Carbohydrate Diet and other manifestations of that theory such as GAPS? I have celiac and do find that some starchy meals leave me w/ terrible indigestion. The GAPS philosophy states that this is because my duodenum, where starch is digested, has been compromised by celiac. I’m currently very much fat-adapted but have found that a starchy meal helps me sleep well. It’s hard for me to eat more than a couple pieces of fruit in a day, and I often struggle to get in 100 grams of carbs. I also read the article you linked about how women might need a bit more starch. Can you offer specific suggestions for those of us w/ celiac or other bowel disorders?

    Teresa Ensslin wrote on November 28th, 2013
  28. I like it whenever people come together and share ideas. Great site, keep it up.

    Anderson wrote on January 16th, 2014

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