8 Dietary Truths We Wish We Could Tell Non-Primal Types

Longtime readers of the blog are so inundated with the latest dietary research and results from years of personal experimentation that they often take the simple, basic dietary truths for granted. But it’s the simple ones that make the most difference. Today I’m going to sift through the knowledge base to winnow out the dietary truths that, while basic, fundamental, and important, are unknown or misinterpreted in the “normal population.” If you think someone you know or care about could learn from this list, send it along.

What follows are some basic dietary truths that everyone needs to understand.

Don’t Cook With (or Eat) Vegetable Oil

Most people know sugar is bad for you. They know they probably shouldn’t be eating white bread at every meal and donuts for breakfast. They may even entertain the potential of a “low-carb, high-fat” way of eating, since the popularity of ketogenic diets and other low-carb diets is exploding into the mainstream. But most people have no idea that industrial seed oils, AKA vegetable oils, are some of the worst substances to put into your body.

Unfortunately, they’re everywhere in our food supply. Most restaurant food is cooked in seed oils. Most salad dressings and condiments like mayo are made with seed oils. Even more unfortunately, they’re a very recent addition. Grains weren’t a staple aspect of the human diet until the advent of agriculture around 10-12,000 years ago, but at least they’ve got some precedent in our diets. Vegetable oils are a wholly modern convention, introduced around the turn of the 20th century as a cheaper replacement for animal fats. We’ve only had access to them for a few generations, and they’ve quickly risen to comprise the majority of the fat we eat. This is bad news, because seed oils are mostly linoleic acid, an omega-6 polyunsaturated fatty acid that’s very unstable and prone to oxidative damage when exposed to heat.

Over the last 50 years, during which seed oil consumption skyrocketed, the linoleic acid content of adult human body fat in the United States increased by 136%. Since our bodies make inflammatory compounds and build cellular structures using that body fat as the foundation, the rapid, unprecedented shift toward linoleic acid has created an inflammatory environment within the modern human.

There are better choices: avocado oil, olive oil, coconut oil, red palm oil, butter, ghee, lard, duck fat, animal fats in general.

And taking fish oil or eating fatty fish like salmon or sardines can counteract some of the negative effects of industrial seed oils—but you should also work on eliminating them from your diet altogether.

Your Brain Can Burn Fat, Not Just Carbs

The brain requires glucose. True. The brain cannot live and function on fat alone. True. But it is patently untrue that the brain can only run on carbohydrate.

Given sufficient adaptation, the brain can derive up to 75% of its fuel from ketone bodies, an alternate fuel source generated from fat metabolism.

This means that the naysayers who warn you away from eating low-carb because “your brain needs carbs”—even if it’s helping you lose weight and feel great—are wrong. In fact, if you become fat-adapted—really adept at burning your own body fat for energy when you aren’t eating and burning the fat you eat when you are—you can produce and utilize large amounts of ketones, which may provide cognitive benefits, especially for people at risk of neurodegenerative diseases like Alzheimer’s or Parkinson’s.

You Don’t Need To Eat 6 Small Meals a Day

Consider why body fat even exists: as a powerful energy source. Gram for gram, fat is the most calorically dense fuel source the human body can utilize. A single pound of human body provides around 3500 calories, and most of us carry dozens of pounds of fat at any moment, giving us many thousands of pounds of caloric energy available at all times. That energy is there to provide fuel during lean times, famines, war, long hunting trips. And, yes, in between meals.

Eating a meal and coasting off the food you ate plus body fat when required is the normal state of human physiology. Before fast food joints, before drive-thrus, before snack bars, before 24-hour grocery stores, we had love-handles.

Recent research indicates that eating 2 or 3 meals a day is just as effective at quelling hunger and enabling fat loss as eating 5 or 6—and eating fewer times per day may even be superior to eating many times per day.

Eating more frequently worsens glucose control in diabetics, for example. And in aging adults, going 5-6 hours between meals and avoiding snacks altogether was the best way to prevent weight gain.

Real Soda Is Worse For You Than Diet Soda

I get it. Those fancy bespoke sodas are delicious. But just because they use “natural organic cane sugar” instead of artificial sweeteners doesn’t make them better choices than diet soda.

I’m no fan of diet soda. As I’ve written before, many artificial sweeteners seem to have a negative effect on gut health, and relying on them may make it harder to kick the sweet tooth than just going cold turkey. But let’s not mince words: They’re better for you than sugar-sweetened soda.

A 2015 study found that sugar sweetened beverage consumption was associated with fatty liver, while diet soda was not.

Regular intake of sugar sweetened soda was associated with the worsening of insulin resistance, while diet soda was not. In type 2 diabetics, drinking regular soda elevated fasting blood glucose. Diet soda did not.

Let me be clear: drink neither. But if you choose to drink one, drink diet.

Most People Should NOT Avoid Salt

A subset of the population has “salt-sensitive hypertension,” meaning their blood pressure rises with too much salt in the diet. About 50% of people with hypertension are salt-sensitive, mostly older people and people of sub-Saharan African ancestry—probably due to their evolution in an environment where retaining salt increased survival.

For most people, salt reduction harms health, rather than helps it.

One study showed that seven days on a low salt diet increased insulin resistance in healthy men and women when compared to a higher-salt diet.

Another study showed that reducing salt improved the blood pressure of hypertensive patients by a mere 4.18 and 1.98 points for systolic and diastolic, while also  increasing triglycerides and LDL and elevated stress hormones.

Folks with a “medium” salt intake live longer than people who eat low salt or too much salt. That amounts to roughly 4000 mg of sodium, or close to two teaspoons of regular salt.

It’s actually more effective to just focus on eating enough potassium-rich foods, like leafy greens, zucchini (and other summer squash), avocados, and bananas. Even red meat is quite high in potassium, provided you consume all the meat juices (let your steak rest before slicing).

Consider two recent Cochrane meta-analyses. The first, on sodium restriction and blood pressure, found that for people with hypertension the mean effect of sodium restriction was -5.39 mm Hg for systolic blood pressure and -2.82 mm Hg for diastolic blood pressure. In normotensive people, the figures were -2.42 mm Hg and -1.00 mm Hg, respectively. What happened when they looked at potassium and blood pressure?

The upper intake of potassium was associated with over a 7-point drop in systolic blood pressure and a 2-point drop in diastolic blood pressure, but only in people with hypertension (the people who actually should lower blood pressure). Unfortunately, the official recommendations for sodium and potassium intake cannot be met simultaneously. If you eat as little sodium as they want you to eat, you can’t eat as much potassium as they recommend.

There’s No Need To Drink So Much Water That You Pee Clear

The trend of average everyday people being unable to last half an hour without a half gallon of water on hand is mind-boggling to me. We’re told to hydrate so much that our pee looks like Fiji Water. There’s no evidence, however, that this does us any good at all. Instead of relying on the experts to gauge how much water you need, listen to your body. Are you thirsty? Drink. Are you sweating? Replace the lost water by drinking some.

Now, if you’re about to train, hike, or compete in hot weather, you’ll need more water. You’re performing a suprephysiological behavior, and your natural sense of thirst may not suffice. It helps to add some salt to your water; you’ll actually improve your hydration status and increase your subsequent performance. I’ll go ahead and recommend that everyone add a pinch of salt to at least one of their glasses/bottles of water each day to aid hydration.

The Human Digestive Tract Does NOT Resemble an Herbivore’s Digestive Tract

Contrary to popular (vegan) belief, humans are not herbivores. We are hunters and gatherers. Our stomach pH is highly acidic, resembling that of scavengers like vultures for whom the acidic stomach environment protects against high pathogen loads in carrion.

Steak Is Better For You Than Chicken Breast

White meat gets a free pass. It’s the “healthy” choice. While it seems like every other week there’s a new study proclaiming “red meat” to cause cancer, heart disease, diabetes, autism, unrest in the Middle East, and the ascension of whichever political figure you oppose, you rarely see similar headlines for white meat. It’s no surprise that most people assume red meat, like beef or lamb, is unhealthy and white meat, like chicken or turkey, is healthy.

The studies that link red meat to poor health outcomes inevitably lump red meat  in with “processed meat,” creating a super-category that includes hot dogs, lunch meats, sausages, as well as fresh beef and lamb. They don’t just analyze fresh, unprocessed red meat. They place grass-fed ribeyes and the Oscar Mayer wieners in the same box, then claim everything in that box is bad for you.

I’ve got nothing against white meat. A good roast chicken is one of my top culinary experiences and, as you’ll see below, it’s a great source of protein and certain other nutrients. But gram for gram, steak trounces chicken breast in nutrient density.

A half pound of chicken breast and a half pound of lean sirloin steak are each about 10 grams fat and 70 grams protein.

The steak gets you all the iron, zinc, selenium, vitamin B12, vitamin B6, and vitamin B3 you’ll need in a day. The chicken breast gets you 30% of the iron, 100% of the selenium, 25% of the zinc, all of the vitamin B3, and most of the vitamin B6 you’ll need. Furthermore, red meat is a great source of creatine, which improves cognitive and muscular performance.

There are more truths to learn and mistruths to unlearn, but this a good start.

Take care, everyone, and thanks for reading—and spreading the word!


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Li C, D’agostino RB, Dabelea D, et al. Longitudinal association between eating frequency and hemoglobin A1c and serum lipids in diabetes in the SEARCH for Diabetes in Youth study. Pediatr Diabetes. 2018;

Kahleova H, Lloren JI, Mashchak A, Hill M, Fraser GE. Meal Frequency and Timing Are Associated with Changes in Body Mass Index in Adventist Health Study 2. J Nutr. 2017;147(9):1722-1728.

Ma J, Fox CS, Jacques PF, et al. Sugar-sweetened beverage, diet soda, and fatty liver disease in the Framingham Heart Study cohorts. J Hepatol. 2015;63(2):462-9.

Ma J, Jacques PF, Meigs JB, et al. Sugar-Sweetened Beverage but Not Diet Soda Consumption Is Positively Associated with Progression of Insulin Resistance and Prediabetes. J Nutr. 2016;146(12):2544-2550.

Olalde-mendoza L, Moreno-gonzález YE. [Modification of fasting blood glucose in adults with diabetes mellitus type 2 after regular soda and diet soda intake in the State of Querétaro, Mexico]. Arch Latinoam Nutr. 2013;63(2):142-7.

Morris DM, Huot JR, Jetton AM, Collier SR, Utter AC. Acute Sodium Ingestion Before Exercise Increases Voluntary Water Consumption Resulting In Preexercise Hyperhydration and Improvement in Exercise Performance in the Heat. Int J Sport Nutr Exerc Metab. 2015;25(5):456-62.

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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