We’re hearing this a lot lately, that we should increase the plants in our diets and decrease the animal products, so I wanted to add my two cents. There is some correlational (relationship based, not causation) and some clinical (applied with many variables, not basic science) research that supports this idea. These studies tend to lump Big Macs (bun included) in with 100% grass-fed steaks, so there are big problems with this research. There are also studies that support the opposite. Like any other fad dietary change, the notion has taken off as gospel truth throughout all industries, and there are now many products to help us incorporate more plants into our diets or to decrease the effects of eating too many animals. It’s an incredibly lucrative industry, and it seems like everywhere I go I encounter people trying to sell me on the idea that their product or service can help me and my clients with the problems of eating too much meat and not enough plants.
First let me say that anyone eating the Standard American Diet (SAD) has to get off of the processed foods (including any fast or prepared foods) and eat real food of any kind, preferably cooked at home, and any move in this direction is a move in the direction of health. I don’t care what diet you’re following, if it is composed of real food your health will improve.
What are the effects on our bodies of moving to a more plant-heavy diet? The first thing people think of is getting more fiber to help with smoother elimination. I have clients come in all the time saying they are trying to eat more fiber to be healthier. I’ll talk more about fiber and gut health later, but one thing is becoming more and more clear: not everyone responds positively to a heavy-fiber diet. Fiber can actually have the opposite effect, gunking up the works, making elimination more difficult and uncomfortable. Plants are very hard to digest, which is why herbivores (plant-eaters) have very long intestines (and sometimes multiple stomachs) and carnivores (meat-eaters) have short intestines (human intestines, by the way, are somewhere in the middle, as we are omnivores, eating both meat and veg). You know all of those scary ads for colonics and whatnot that say that we have undigested meat in our bowels? Yeah, that doesn’t happen. Ask any nurse. The only undigested food found in bowels is plant matter. So why are doctors pushing fiber on us? Because with our SAD diet we don’t get enough to move all of the junk food through our bodies at a decent rate. Stop eating SAD foods and you won’t have this problem and won’t need to bump up the fiber.
Because meat is much more easily digested than plants, backing off of the amount of fibrous plants eaten can help normalize digestion and elimination. One of my clients had been eating a very plant-heavy diet her whole life with no processed foods and had gas and constipation that kept getting worse. What did her doctor do? Put her on Metamucil to add more fiber to her already extremely high-fiber diet. I encouraged her to reduce the plants and ease her way into eating more and more meat. She’s feeling better now for the first time. Increasing the fiber in one’s diet is not necessarily a good thing.
Another thing we know is that a plant-heavy diet drastically reduces the amount of protein that we consume. Consider that the best and only complete source of protein (that has all essential amino acids, or protein building blocks that we have to get from our diets) is quinoa. It takes 6 cups of quinoa to equal the protein we can get in a small steak or a bit larger piece of fish. Who eats that much quinoa? Nobody. Nor should they, just on the basis of carbohydrate toxicity, if nothing else.
There is debate in the clinical research community concerning how much protein we really need. The plant-promoting folks say we should eat less protein than we’re typically told we need, and there are some clinical studies to support this idea. The big scare about eating too much protein has to do with the metabolic pathway that is related to cancer growth. That is the same pathway (mTOR) that allows us to build muscle. It relies on our sugar-burning metabolic system rather than our fat-burning system, so proponents of ketogenic, or fat-burning, diets try not to eat much protein so they can stay in ketosis all the time. That’s why almost all ketogenic diet plans you’ll see have pretty low percentages of protein in their macronutrient allotments.
There are some problems with this approach, however. Dr. Ben Bikman on the basic science end and Dr. Gabrielle Lyon on the clinical end have been doing a fantastic job shining light on the importance of eating more protein, not less. On the basic science end, Bikman has shown in a series of wonderful studies that just because our liver can engage in gluconeogenesis to make sugars from proteins, it won’t do so unless it has a need to do so. So keto dieters need not limit the protein they ingest, because it won’t throw them out of ketosis. The evidence for this assertion keeps piling up. Likewise, those worried about feeding cancers and pre-cancers, which eat sugar almost exclusively, need not worry, either, as engaging the mTOR pathway won’t increase risk of cancer growth.
Dr. Lyon is a former figure competitor with extensive experience and expertise in the health of elite athletes and older populations. She is a muscle-centric physician who keeps up with both basic and clinical research. Muscle is the largest organ in the body, and it is metabolically active. Sarcopenia, or age-related muscle loss, is seen as a normal thing in our society, but it isn’t normal in the history of humans. Many chronic illnesses can be argued to start with sarcopenia, which changes our biochemistry to perpetuate those illnesses. Early in life, our hormones dictate the amount of muscle we have on our bodies. As we get into our 30s, however, muscle tissue is supported not as much by hormones as by protein intake, specifically complete proteins containing branched-chain amino acids (BCAAs). We need a certain amount of them to stimulate that mTOR pathway for muscle growth and maintenance. This may kick us out of ketosis briefly, but that’s normal. We shouldn’t be chasing ketones, anyway, but drifting in and out of ketosis as we shift from one metabolic pathway to another throughout the day. Our bodies evolved to use both pathways for metabolism, or they wouldn’t both be there. We should not be trying to shut one down completely. Dr. Lyon recommends eating at least 30 grams of complete protein (not including collagen) three times per day – more if you’re older or out of shape. There is really no practical way to get anywhere near that much protein from plants, unless we supplement with processed vegetable proteins (not a natural thing for humans to do). The bottom line is that the jury is still out when it comes to the amount of protein we need, but it’s looking like we may need more than we thought.
And that’s just muscle-supporting protein. We also need collagen for healthy hair, skin, nails, connective tissue and joints, which we make less of as we age and which we can only get from animals. There are no plant sources of collagen. We get it from eating the skin with our chicken, the membrane on the back of a rack of ribs – all animal protein has collagen packaged with it. It also has the healthiest, most easily digested fats packaged with it (no, animal fat does not cause heart disease or clogged arteries). Those fats are the necessary raw materials to make all of our cell membranes, hormones, nerves, etc. Going meat-free clearly does not constitute a diet for optimal human health.
Another argument for a plant-heavy diet is that an animal-heavy diet makes our bodies too acidic, which they say causes all kinds of chronic diseases. Plants alkalinize our bodies, which is healthier, they say. This scare also turns out not to have any basic research behind it. Our ancestors ate varying amounts of plants and animals, sometimes almost exclusively one or the other, depending on what food sources were available, and no chronic illness existed. None. Different parts of our bodies need to be kept at different pH levels or we die, so our bodies have mechanisms to keep our pH levels right where they need to be for optimal body functioning, regardless of the amount of plants or animals we’re eating. If eating a meat-heavy diet made any part of our bodies so acidic that we wound up with a chronic illness, humans likely would have died out many, many years ago. What we know precipitates chronic illness is stress coupled with toxins, including high carbohydrate intake, or infection. This acidity argument, in short, makes no sense.
Then there’s the gut microbiome argument. Now here’s something to consider! We are only 10% human genes – the other 90% are bacterial. We are walking bags of bugs and would not survive otherwise. We have to feed those beneficial bugs so that we stay healthy, and they really, really like probiotics, or fiber, from plants. If we do not feed them, they die and other, not-so-beneficial and potentially harmful bugs take their place. These bad bugs like Big Macs and fries. They also like sugar and chemical-laden Frankenfoods, like honey buns and Snickers bars. What we feed ourselves in part determines what bugs are there, and we want more of the helpful ones and less of the bad ones. This probably also greatly impacts chronic disease, though the science on this is very new. But here again, some of our ancestors didn’t eat lots of plants to feed their good bugs and had no chronic illness. Today, there are many people with autoimmune conditions who cannot eat some plants or any plants at all if they wish to stay symptom-free. There is no research on carnivore (all meat) diets, yet, but there are too many people benefitting from this way of eating to make the bug argument air-tight – unless those bugs also really like a good 100% grass-fed steak.
So where does that leave us? Eating the greatest variety of plants and animals – real food, raised naturally, not by corporate farms that deplete the nutrition in the soil and in the food – logically gives us the most nutrients to feed our good bugs and give us the protein we need. When we get rid of the Frankenfood and the grains and beans that we never really evolved to digest effectively, we might feel great with all of the meat and veg/fruit we want. We may need to back off of the fruit due to the extreme and unnatural sugar content of modern fruits. Some of us may still not feel optimal, though, so we may need to back off of nightshade and/or FODMAP veggies or even stop eating all plants entirely. Or if you feel better eating less meat and more plants, do that. A very cool thing happens when we eat real food: we are more tuned in to what our bodies tell us they like or don’t like. Eat everything that your body tells you it likes and don’t eat what makes it feel uncomfortable in any way. Your body should be the final authority that you listen to, not anyone else.