Paul Saladino, the guy promoting the Carnivore Diet, actually thinks that most humans would be healthier if they adopted a plant-free diet on a permanent basis.
Can eliminating all plant foods really be the key to weight loss and better health?
Nutrition Diva is hosted by Monica Reinagel. A transcript is available at Simplecast.
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Hello, I’m Monica Reinagel and you’re listening to the Nutrition Diva podcast.
I recently got an email from Matthew, asking me to weigh in on the Carnivore Diet.
“My brother recently started the Carnivore Diet and has lost almost 15 pounds in a month from eating nothing but meat and dairy products. The doctor promoting this approach maintains that vegetables are toxic. What’s more, he says that you get more nutrition per volume unit of meat or dairy than from the same volume of vegetables/fruits.”
The weight loss that Matthew’s brother has experienced is not surprising, given that this is essentially a very extreme version of the ketogenic diet. When dietary carbohydrates are severely restricted, the body goes into a state of ketosis. This is an alternative metabolic pathway that converts fats into ketones, which can be used as cellular energy in place of glucose, which is the usual energy source.
One side effect of ketosis is appetite suppression—and this is what makes the ketogenic diet popular for weight loss. To be clear, you still have to reduce calories in order to lose weight on a ketogenic diet. But you may not be as hungry as you might otherwise be on a reduced calorie diet.
The problem with ketogenic diets as a weight loss strategy is that rebound weight gain is a big problem. Once you go back to a more balanced diet, any weight you’ve lost is likely to come back. Often with interest.
But Paul Saladino, the guy promoting the Carnivore Diet, actually thinks that most humans would be healthier if they adopted a plant-free diet on a permanent basis.
What are his arguments?
First off, he’s convinced that plants are varying degrees of toxic. This is similar to the arguments made by Stephen Gundry in his book The Plant Paradox. Gundry claimed that lectins, a compound found in vegetables, fruits, whole grains, nuts, seeds, and legumes, may in fact be “the cause for most common health problems.”
The human diet has always contained a wide variety of lectins. In fact, lectins perform a variety of functions in the body, including participating in our immune response. Certain lectins are being studied for their potential role in protecting us from cancer.
A few specific lectins, such as those found in raw kidney beans, are known to be quite toxic to humans. As few as half a dozen raw kidney beans can create severe food poisoning symptoms. Another lectin found in wheat germ has been shown to make lab rats really sick. However, you’d have to eat about 200 pounds of raw wheat germ to get as much lectin as these poor rats were fed. That’s a lot of wheat germ. But most lectins appear to be harmless. Or at least they did, until Dr. Gundry came along.
The evidence implicating lectins in human disease or demonstrating the benefits of avoiding them is pretty thin. Gundry says his own patients have been cured of everything from cancer to heart disease. However, no credible published research exists to support the therapeutic benefits of a low lectin diet. In fact, the evidence that we do have seems to point in the opposite direction. There is a lot of research showing that people who eat more whole grains, legumes, fruits, and vegetables (and presumably take in more lectins) have a lower risk of disease.
So, I feel pretty comfortable dismissing the charge that plants are toxic.
The second argument is that meat provides more nutrients by volume than plants.
Nutrient density by volume (or for that matter, by weight) isn’t a terribly helpful metric. After all, you can increase the amount of nutrients per gram or cubic centimeter simply by dehydrating a food.
And, ironically, foods that have a lot of volume can help us feel full on fewer calories, simply by filling up the space in our stomachs. This is the approach espoused by Barbara Rolls, who has published several popular books about something she calls a “volumetric” diet.
The idea here is to choose foods that have a lot of volume but not too many calories. Primarily, these are foods that contain a lot of fluid or a lot of fiber: soups, broths, whole vegetables and fruits, whole grains, and that sort of thing. Even just drinking a full glass of water before meals has been shown to decrease food intake.
These volumetric foods trigger special cells in your stomach that register pressure or fullness. These then send a signal to your brain that you’ve had enough to eat. (Presumably, this feature is designed to prevent us from eating until our stomachs literally explode.) But because these foods and liquids don’t contain a lot of calories, you end up reducing your calorie intake and losing weight.
We usually measure nutrient density not in terms of volume or weight, but as nutrients per calorie. A nutrient-dense food is one that provides a lot of nutrition for the calories. Because they are so much lower in calories, vegetables are among the most nutrient-dense foods. But obviously, it depends on which nutrients you’re talking about.
For example, you’d have to eat 500 calories worth of watermelon (about 4 pounds!) in order to get the same amount of calcium as in 60 calories (just half a cup) of whole milk. So if you’re only talking about calcium, milk is clearly more nutrient dense than watermelon—both in terms of volume and calories.
On the other hand, you’d have to consume 2600 calories worth of milk (over a gallon) to get as much beta-carotene as you would get from just 30 calories (less than a cup) of watermelon. If it’s beta-carotene you’re after, watermelon is much more nutrient dense (again, in terms of both volume and calories).
But saying that something has more nutrients per calorie (or per pound, gallon, or anything else), is a little like saying that a painting has more color per square inch. That may be true—but it doesn’t tell you anything useful about which colors are or aren’t present.
And my primary concern about a long-term diet of nothing but meat and dairy is that there are a lot of important nutrients which will be entirely absent—including vitamin C (hello, scurvy), fiber (goodbye, gut health) and hundreds, if not thousands, of beneficial disease-fighting phytonutrients. (Remember: “phyto” means “from plants.”) And that’s to say nothing of the increased health risks that are consistently associated with diets that are very high in red meat and/or saturated fats—or the carbon footprint of such a diet.
So, how did this diet catch on when it seems like such a bad idea? Like most fad diets (and bad ideas), this one makes a lot of promises… and there’s not a lot to back them up.
Most of the “evidence” to support the Carnivore Diet comes from anecdotal reports, and in addition to weight loss, they include things like improved glucose control and improved mood. Reducing the amount of sugar and other refined carbohydrates has absolutely been shown in clinical trials to have these effects… but I think these benefits could be achieved with far less drastic adjustments to your diet.
Eliminating all carbohydrates from your diet may also reduce symptoms associated with Irritable Bowel Syndrome, simply because you will have eliminated the foods most likely to contribute to those symptoms. However, it’s a little like throwing out every sweater in your entire wardrobe because the two that contain wool make you itchy.
If you can identify which particular types of carbohydrates are causing issues, you can eliminate them (and reduce your symptoms) but still have a reasonably balanced diet. This approach is known as the low FODMAP diet—and it has a far better track record for reducing gas, bloating and other IBS symptoms than the Carnivore Diet.
What’s more, the Carnivore diet may also have negative effects on the gut. One small published study found that just five days on an all-meat-and-dairy diet was enough to produce dramatic and detrimental changes in the gut microbiome, including an increase in pro-inflammatory gut bacteria.
The Carnivore Diet may lead to quick weight loss. However, unless you’re prepared to stay on a low or zero carb diet for the long term, that weight loss is unlikely to be sustainable. And staying on an all meat diet for the long-term involves significant risk of serious nutrient deficiencies. Hopefully, Matthew’s brother will find his way to something more sustainable before any of those issues develop.
If you’re looking for more support for healthy weight management, please check out the tools and resources that are at weighless.life, where our goal is to help people create habits, mindset, and lifestyle that help them weigh less without dieting. That’s at weighless.life.
If you have a question you'd like me to answer, you can email me at nutrition@quickanddirtytips.com You can also leave me a message at 443-961-6206
Nutrition Diva is a Quick and Dirty Tips podcast. It's audio-engineered by Nathan Semmes with script editing by Adam Cecil. Thanks also to Morgan Christianson, Holly Hutchings, Davina Tomlin, and Kamryn Lacy.
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