May 1, 2015

Food for Thought Friday: Low-Carb Logical Fallacies

Time for another round of things that make us go hmmm.

Last time in Food for Thought Friday, I addressed the issue of ketosis, carbs, and alcohol. I’m pleasantly surprised at the number of page hits it’s gotten. Here, I thought it was kind of a throwaway post, a quick one-off just to get something up on the blog before people forget I exist. But it seems the topic struck a chord, or maybe people just like reading about ketosis & alcohol. (And who can blame them? Either together or separately, they’re great topics!)

Since I pointed out the problems with the keto-haters suggesting ketones are “dangerous” or “unnatural” because the body stops producing elevated levels of them as soon as it has any appreciable amount of glucose in the bloodstream, today I thought I’d point out a logical fallacy that low-carbers are prone to using—myself included. It goes a little something like this:

If dietary fat were fattening, they would use lard, tallow, and butter to fatten cows in feedlots, but they don’t. They use grain. Therefore, grains are fattening. (And we extrapolate this to humans.)

Now, believe me, I agree that this is true. But that doesn’t mean it’s an argument that works well in our favor—especially when a counter-argument we might get from vegans, vegetarians, and what Dr. Richard Feinman calls “the lipophobes” goes something like this:

Cows maintain optimal health by eating nothing but grass. Therefore, animal fats and proteins are unnecessary for a healthy diet. (And they extrapolate this to humans.)

You see the problem here, right?

I’m guilty of using the “they use grains to fatten cattle” logic, myself, but that was in the past. Now that I’ve realized counterarguments are so easy to think of—even if they’re incorrecttry to steer clear. (No pun intended, hehheh.)

It’s a logical fallacy to say that what works for one animal species will work for some other animal species. This is what got us into trouble back in the day, when they fed cholesterol to rabbitsherbivores. So yeah, of course that led to problems in these bunnies’ blood vessels. They were being fed something that is not an appreciable part of their natural, species-appropriate diet.

And when we feed steers and dairy cows foods that aren’t part of their natural diet, of course biological problems ensue. And even though I agree that grains are fattening for humans (at least, those who are insulin resistant and have a low carbohydrate tolerance, since we have plenty of examples of population groups who do not become obese via grain consumption), we have to base that argument in human physiology, rather than on that of ruminant animals.

Just because grains fatten cows doesn’t automatically mean they’ll fatten humans. And just because cows and sheep thrive on grasses and greens, exclusively, doesn’t automatically mean that humans will.

Why? A little something called the digestive tract. Ruminants and humans have digestive tracts that are worlds apart. We are literally different animals, and there’s no reason to assume that we can thrive on the same type of diet. (But I guess the only people making this claim would be anyone who believes humans can thrive on raw green plant matter and nothing else. And not even the raw foodists are saying that, ‘cuz some of them eat raw nuts & seeds, don’t they?) 

I won’t bore you with a long anatomy lesson, but the bottom line is, ruminant animals have multi-chambered “stomachs,” or pouches. One of these is called the rumen, hence the term “ruminant.” (Also, hence the verb “ruminate,” which means to mull something over for a while, turning and churning it this way and that, just like happens to food inside the rumen.)

A rumen is a gigantic fermentation vat. It’s like a sauerkraut crock right there inside cows, sheep, goats, and other ruminants. The chambers of these digestive tracts are loaded with bacteria. They are loaded with certain species of bacteria that human GI tracts do not harbor, and these bacteria help cows convert the cellulose of plant material (carbohydrate) into protein, which you might be familiar with in the form of delicious things such as brisket and filet mignon.

And as long as I’m on the subject, I’ll introduce another logical fallacy I’ve used in the past: cows produce plenty of poop without any “added fiber” in the form of whole grains or flaxseeds. Yes, green vegetation is loaded with indigestible plant fiber, and ruminants eat a ton of this green vegetation, but that just goes to show that feces can be produced just fine in the absence of high-fiber cereal, bran muffins, or Metamucil and psyllium husk. (In fact, if you ask a farmer raising his steers exclusively on grass, he/she will confirm for you that they produce plenty of poop.)

Way back in the digestion series, I said, “Obligate carnivores, like lions and tigers, don’t spend their days on the savannah chomping down on endless piles of kale, broccoli, or bran muffins, and they seem to defecate pretty well without pharmaceutical intervention. I’m not suggesting the anatomy and physiology of these big cats are the same as humans, so therefore we don’t need any fiber, either. I’m simply pointing out that somewhere in nature there exists a mechanism for allowing healthy animals to excrete feces without the need for copious amounts of plant fiber.” Obviously, plenty of animals excrete dung without isolated fiber from grains, seeds, or copious amounts of green vegetation. (Or almost any vegetation, for that matter. In fact, I’ve been giving a lot of thought to this as it regards humans, so be on the lookout for a couple of posts on whether vegetables are "required" for people.)

To recap: in the animal kingdom, we have species that thrive (and poop) on plant-only diets. And we have other species that thrive (and poop) on animal-only diets. However, in the interest of intellectual honesty here, let me point out that in the course of eating so much vegetation, we have to assume ruminants are also consuming a lot of insects, worms, larvae, and whatever other tiny critters might be lurking in all that grass. But we can hardly call them carnivores. And even obligate carnivores and “mostly” carnivores still occasionally consume plants, but we wouldnt call lions and tigers herbivores.)

So yes, we have widely varying diets that work well for the widely varying anatomy and physiology of different animal species. But the reason those widely varying diets work is because the species have widely varying anatomies & physiologies. To suggest that grains fatten humans because they have been shown to fatten cows is a leap of logic as shaky as suggesting that raw grass and nothing but raw grass can keep humans healthy because it keeps cows healthy. (This is just as unhelpful as postulating that all humans can thrive on high starch diets because the Kitavans do, or that we can all thrive on high meat and fat diets, because Arctic peoples do.)

Again, I’m not saying grains don’t or can’t fatten humans. I’m saying only that if we use the grains/feedlot/fattening angle, we should be prepared to back it up with something based on human anatomy, digestion, and endocrinology, rather than the logical misstep of extrapolating from ruminant physiology to our own. We have the answers (at least, I think we do), but we strengthen our case by knowing why they’re the answers.

Remember: Amy Berger, M.S., NTP, is not a physician and Tuit Nutrition, LLC, is not a medical practice. The information contained on this site is not intended to diagnose, treat, cure, or prevent any medical condition.


  1. May be extrapolation from pigs is more accurate than from ruminants or rodents There are too wide extrapolation from the blogger, but there are also some interesting facts like corn is more fattening than wheat and barley,
    "Pigs who were fed molasses and cane juice products the night before slaughter had a 34% larger liver than pigs who were fed a traditional grain-based diet. A larger liver = a sicker liver. Adding sugar to a pig’s diet increases their rate of carcass growth. Weanling pigs have a greater growth performance when they eat milk chocolate products leftover from the candy making industry. Go figure. Pigs who have diets that are sweetened end up eating more. In fact, simply giving the pigs a sweetener increased their chewing behavior. Ever feel the need to chew something, even though you’re not hungry? You’ve probably been eating too much sugar."
    "Pigs that are grown in confinement (most of the pigs that are raised for meat in the US) grow at a faster rate than pigs that are raised on pasture. "

  2. "Feed them(pigs) skim milk" for fattening was also an interesting tip.

  3. It might be apt to say that even herbivores (like cattle) and birds whose natural diet includes grains get fat on a grain-based diet.

  4. Lierre Keith has a excellent explanation of how cows derive energy from their food. The grass they eat feeds the bacteria in their stomach (or rumen). The bacteria then thrive and multiply. The cows - in turn - actually live off the bacteria which is largely protein and fat. P. S. I love your writing.

    1. :D Thanks, Esmee! In an alternate universe (or this one, very soon), I'm a successful novelist, so it's always really heartwarming when someone compliments my writing. I enjoy conveying this kind of information to people, and I like knowing someone, somewhere, is learning something, but it's especially nice when people notice the writing itself isn't half bad. ;-)

  5. Yes! I cringe every time I hear that "they fatten cows with grain" analogy. Bloody hell folks, do better than that. That's some very weak tea and it just makes you look quite woefully ignorant on the topic. Think.

  6. Yes pigs much closer to humans in terms of stomach and intestines also diet.
    I grew up on a market garden, we always raised pigs for personal consumption feeding them table waste and waste/excess veges. Usually they would receive most calories via kumara(sweet potato) but one year we had an enormous carrot crop and so that year is was carrot feed pork. Carcass weights were similar but carrot feed pigs were too lean, lean pork is unappealing you need a nice layer of fat which kumara provides amply.

    1. As a human, I can tell that raw carrots are not 100% digested , especially when consumed in a big amount. I have a nice recipe for marinated carrots and eat it from time to time. It doesn't mess up my LC diet, but I am careful not to eat too much , or it would stimulate GI tract to an uncomfortable degree.

  7. Hey Amy. Thanks for stopping by my blog. This is great post. Having studied human evolution (and their co-evolution with animals and plants), I thank you for this! "To suggest that grains fatten humans because they have been shown to fatten cows is a leap of logic as shaky as suggesting that raw grass and nothing but raw grass can keep humans healthy because it keeps cows healthy." Bam, spot on. There is a ton of this erroneous extrapolation out there. Most recently, everyone freaking out because fruit flies die when they consume Truvia (erythritol) and now it's being called an insecticide. Well, I have an infestation of ants in my house and they die when I spray them with a mixture of water, dish soap and olive oil. Pretty sure that if you sprayed me with the same mixture, I'm not going to keel over on contact.

    Good stuff!

    1. Thanks! I'm glad we've discovered each other. And yeah, I agree that grains *can/do* fatten humans, but it does our nutritional perspective no favors to keep going back to the feedlot analogy. I think cinnamon is supposed to be bad for ants, too. Oh, no! Guess I better not eat any anymore! (Cinnamon, that is; not ants, hehheh.)

  8. I don't often get around to check your blog, but when I do it is always good.

    While an evolutionary perspective is great for getting people to consider that "hmm, maybe it isn't a stretch to think that millions of years of evolution hasn't properly equipped me to run on 2 liters of Coke a day", folks have definitely relied on several logical fallacies to support certain nutritional ideas. Even if a premise can be supported by other solid arguments, piling on some poor logic just to make things more appealing is still just poor logic and needs to be called out. Humans aren't equivalent to cows, or pigs, or anything else that has ever walked the earth. Heck, people of different genetic backgrounds aren't even equivalent in regards to dietary effects. Dairy and lactase persistence for example.