Dear Mark: Ketosis and Methylglyoxal, Microwaving Vegetables, the Role of Salt in Cooking, and More Veggie Ideas

mailing list drawn by hand isolated on blackboardFor today’s edition of Dear Mark, I’m answering three questions. First, what’s the deal with the relationship between ketosis and methylglyoxal? Second, why did I recommend using the microwave to cook vegetables in the post from last week? Third, why do chefs use so much salt in their cooking? After all the questions, I throw in a couple more vegetable cooking tips I missed last week.

Let’s go:

Hey Mark,

Did you see this study? Ketosis unlocks a “new” antioxidant system. Pretty cool stuff, just thought I’d pass it along.


Thanks, Noel. That was totally new to me. I knew that ketogenic diets had antioxidant effects, but I didn’t know the ketone bodies themselves were directly involved in detoxification of otherwise toxic compounds. Very cool. I agree.

What’s going on?

Methylglyoxal is one of the most reactive agents our bodies encounter. Many of the basic diseases of civilization, like diabetes, hypertension, and heart disease, feature elevated methylglyoxal levels. Causation is likely. Heck, it even possesses the ability to corrupt HDL.

What makes this newest study so interesting is that ketogenic diets have gotten a bad rap for their supposed effects on methylglyoxal levels in the past. Detractors commonly cite a 2005 study of the Atkin’s diet, which found that dieters who reached ketosis doubled their methylglyxoal levels. Sounds bad, but is it?

According to this latest study, maybe not. One of the main ketones, acetoacetate, gloms on to methylglyoxal and converts it to a harmless metabolite. Elevated methylglyoxal might mean very different things depending on what kind of a diet produces it.

Other studies have found methylglyoxal to be a potent anti-cancer agent whose users “benefited greatly,” some even becoming “free of the disease.” Methylglyoxal has a hormetic effect, too. That means it can provoke a beneficial response in the right dose, making us stronger and healthier than if we’d never encountered it at all.

I’m kind of shocked you include microwaving anything as an option.


I hear you. I’ve always been on the fence about microwaves.

The purist in me feels guilty whenever I microwave something. Cooking over fire or on the stove is intimate. You’re close to the food. You’re touching it. You’re putting yourself into the dish. Cooking in the microwave is putting food in a box, closing it, pressing some buttons, and walking away. It’s very clinical.

The “suspicious of modern food processing” part of me tingles when I think about microwaving. Maybe, just maybe it is destroying the integrity of the food, forever altering the molecular structure of the water within, and creating carcinogenic compounds. Sure, the studies don’t really show it, but couldn’t they be industry-funded?

But another part of me realizes that microwaves save a ton of time. They’re very convenient. And that studies seem to vindicate microwaves. Some even show that microwaving is the most gentle way to cook certain foods and preserves the most nutrients. I can’t come up with a good, evidence-backed reason not to use the microwave.

I wouldn’t microwave breast milk. But I would microwave my bone broth.

Some additional thoughts regarding salt… Processed foods, fast foods, and restaurant foods can contain considerably more salt than what most of us would cook with from scratch at home. This is because salt covers up the fact that shortcuts have been taken in the preparation, sometimes to the point that such foods have little flavor of their own.


While I agree salt is often used in lieu of quality and creativity, I’d also suggest that ultimately salt isn’t there to make food taste salty or cover up imperfections and mistakes. It enhances flavors. It highlights them. Try turmeric by itself—a dash of powder on your tongue. Virtually tasteless. Now, add some salt. It’s a totally different experience. You can actually taste the turmeric more when you pair it with salt than when it’s by itself.

One reason is that salt suppresses unpalatable flavors (like bitterness) more than palatable flavors (like sweetness), thereby tipping the balance toward the enjoyable flavors.

Another reason is that sodium enhances sensitivity of sweet receptors. You actually taste more sweetness when you add salt. That explains the sudden and meteoric rise of salted caramel-flavored foods.

Even macaques know this. Given access to both salt water and fresh water, they dip their food in the former to enhance the taste.

And now for the vegetable cooking tips I promised up above….

Treat whole garlic cloves like vegetables.

Unless you enjoy peeling dozens of cloves, get yourself a sack of peeled garlic. I like the big bag sold at Costco.

You have to really love garlic for this to work. But if that doesn’t describe you, I’m not sure we can be friends anymore.

Whole garlic cloves go really well with roasted cauliflower. For whatever reason, they both cook to perfection in a cast iron pan at 425° in about 30 minutes, tossed in EVOO or avocado oil.

Got a stir fry going? Throw in some garlic cloves. Smash half and leave the rest whole. Mix up the textures and flavors (smashed, garlic cloves become more pungent and display more potent polyphenols).

Want to get crazy? Roast an entire pan of garlic cloves. Nothing but garlic, fat, and some salt. Try not to eat them all in one sitting.

Fair warning: Garlic is extremely high in inulin, a potent prebiotic fiber. You will fart. Prepare for that. Most people aren’t eating garlic in volume, but those who embark on this challenge will.

Torch your veggies.

Get yourself a little butane torch, read the instructions, make sure you know what you’re doing. Avoid open gas lines. Start exploring.

I find almost everything takes to the torch. In fact, I haven’t had any bad experiences. Of course, don’t try torching cucumbers or anything silly like that.

Torch it dry, then dip in oil and sprinkle with salt. This retains the crispness and the sweetness without causing conflagrations (fat is flammable).

Learn the fine line between blackened and burnt. Traverse that line as often as you can, for it is where flavor lies.

That’s it for today, folks. I hope you enjoyed today’s set of questions and answers. If you have anything to add or ask, do so down below. Thanks for reading!


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.

If you'd like to add an avatar to all of your comments click here!

43 thoughts on “Dear Mark: Ketosis and Methylglyoxal, Microwaving Vegetables, the Role of Salt in Cooking, and More Veggie Ideas”

Leave a Reply

Your email address will not be published. Required fields are marked *

  1. Hi Mark – it would be great to learn more about how you do Primal when vacationing & traveling.

    I remember you went to Greece several weeks ago – were you able to eat primal? If so, how did you do it?

    Thank you as always for the great insights!

    1. Not Mark, but personally I find that it’s easy to eat Primal almost anywhere (except in US strip malls, where what passes for food seems pretty scary to me).

      In Greece – lamb, fish, vegetables, olives, cheeses if you tolerate dairy… I don’t see why this would be a challenge!

    2. Forgive me for jumping in but Greece is the easiest place to go primal. Lots of vegetables (cooked and fresh served), extra Virgin olive oil, excellent whole yogurts, high quality fresh seafood and succulent lambs meat. Not to mention fresh fruits that taste like the real thing and of course a variety of local cheese. You can be primal or keto easily

    3. Great question. Can’t speak for Mark but can say I have no trouble keeping Primal when traveling. I love to travel and eat out…there are so many great choices everywhere I go. I just stick to protein, healthy fats and plenty of produce. So easy. Going to the Bahamas in November…just another eating adventure…no prob staying Primal

    4. Thanks all, for the replies.

      I assume all of you don’t worry too much about achieving primal perfection when travelling.

      e.g. is the meat grass-fed, are the eggs pasture-raised, are the vegetables organic, is the food cooked in a healthy oil or a rancid vegetable oil

      Based on my experience, I have to turn a blind eye to the above (and other primal principles) to make it work when travelling.

      1. Markus, I don’t worry overly about those things even when eating at home, much less when I’m traveling. Grass-fed, pasture-raised, and organic are, of course, preferable when available and affordable, but too much focus on attaining perfection can be counterproductive.

      2. I agree Markus, I travel extensively worldwide and run into the same challenge. Mark, any suggestions?

      3. On vacation, relax and don’t get too obsessed with food. You can also still be 70-80% Primal if you’re careful and make the right choices. You should actually never seek Primal perfection.

    5. I recently spent time in Croatia. I’d assume the food is similar in the North Adriatic as the southern Adriatic. I just stuck with starter plates, grilled squid, octopus salad etc. The only problem was the local wines were so good I had to try them all. Don’t knock yourself out. Gaining weight on vacation means you enjoyed yourself. It’s OK to take a vacation from the Primal lifestyle too.

  2. “I can’t come up with a good, evidence-backed reason not to use the microwave.”

    Agreed, I’ve done the online research myself. Plenty of other science-backed issues to worry about.

    1. +1. I’ve never actually cooked with a microwave but I do use it to reheat certain foods. I’ve always felt that the anti-microwave crowd were a bit on the alarmist side.

      1. I think that it’s what we don’t know that might hurt us… Proteins denature and form tangled messes with high heat. Now what’s your body going to do with that stuff? The point is that we don’t know, but it’s probably not good.

        We assume that the web holds all answers at our peril.

        1. “with high heat” – it’s the heat that causes the denaturing, whatever the source of the heat. It’s not just a microwave oven issue

          I recently spent 9 days in the wilderness with no heated food – I’ll take my chances with a few tangled proteins…

        2. Come on Jeff. Dietary proteins are supposed to denature/coagulate. They usually do so at 55-60 °C so any heating method will cause them to do so. And if you eat raw protein sources like nuts or beef carpaccio or sashimi etc., the proteins will denature in your stomach – which has a lower temperature but an acidic environment (which also facilitates the denaturation/coagulation of proteins. And for good reason: denaturation is a prerequisite for further protein digestion.

    2. “forever altering the molecular structure of the water within” – if you alter the molecular structure of water, it isn’t water anymore.

      Microwaves excite motion in the water molecules in food, causing them bump into each other and heat up, thereby heating the food. There is no change in the structure of the water molecules. Nutritional changes in the food is due to the food getting warmer, not the microwave radiation, and such changes are similar to, or in some cases markedly less, than any other method of heating the food.

      If you’re worried about microwaves affecting your food, I’d suggest you first get rid of your cell phone. It uses frequencies in the same range (1-2GHz-ish) as your microwave oven, and you’re holding it right next to your brain.

      On the other hand, 20-some years ago the world embarked on an uncontrolled, in-situ test of the risk of microwaves affecting human tissue, by billions of people holding those phones next to their heads for hours every day. If there have been massive increases in diseases of the ear or skull or brain, I’ve missed the reports….

      1. Perfect, John. “Microwave hysteria” is quack science at its best. Microwaves are perfectly safe. This is the kind of remark that I wouldn’t expect Mark to make…

  3. Mark, you put “get yourself a little butane torch” immediately after warning “you will fart.” You had to expect our brains to put those two things together in a rather predictable and childish fashion…

    1. LOL! I got a good belly laugh from this! I didn’t make the connection. Then again, I didn’t ever know that people lit their farts in science lab until much later in life.

  4. Dear Mark-What’s the best process for curing a sugar addiction, specifically to chocolate? Do you recommend quitting cold turkey, or going “primal” by eating dark chocolate in moderation? What other steps can be taken to remove or lessen the issue? I really want to become fat adapted, yet can’t seem to get off the sugar craving hamster wheel.

    1. Here’s what I did. Don’t worry about moderation; it should come on its own. Just get darker and darker chocolate. Move a level up every two weeks, or on whatever schedule works for you.

      1. I like that idea! I have tried 88% before and it seems to upset my stomach a little. Maybe I’ll work my way up. Were you able to quit it all together, or do you still eat dark chocolate?

        1. Maybe you need to get better chocolate? Not all 88% is made alike. Many more places are offering quality bean to bar chocolate these days – specialty coffee shops are good places to look. Don’t think organic necessarily – a lot of the world’s best chocolate is not, just like the world’s best coffee. A shop in New York City called The Meadow has an amazing selection you can peruse online. Warning – it’s not cheap, but if you’re used to lower quality chocolate such as Lindt, you’re in for a treat. (I’m not affiliated with them in any way. I don’t even go there much – there are sources closer to my apartment with smaller but still wonderful collections.)

          I find myself even eating 100% these days. I’ve evolved into enjoying it more as a vegetal flavor than a sweet treat.

      2. That answer worked for us. Move up to 90% dark (3 grm sugar/serving). Pretty good, but not addictive. We took several bars on a 5 day hiking trip and we so lost interest in them that we didn’t even eat two of them. First time that’s ever happened!

        Most other chocolate is just glorified sugar.

    2. I’m not Mark, but judging from my own experiences as a sugar addict I would say cold turkey is the only thing that works. (I know you didn’t want to hear that.) I found that any time I ate sugar in any form (including dark chocolate), I was fanning the flames of my addiction. Switching to artificial or alternative sweeteners (like stevia) tended to do the same thing via a slightly different path. They simply amplified my desire for the “real thing” i.e. sugar. Interestingly, fruit did not have this effect on me, although apparently that’s not true for everybody..

      On the other hand, when I went cold turkey and eliminated ALL sweets except fruit, I lost the cravings for sugar within about a week. The good news is that you can eventually eat small amounts (say a bite or two) on rare occasion, but you’d do well not to do it often. Sugar addiction can go into “remission” but never completely disappears, and it takes very little for the cravings to come roaring back to life.

      1. You’re right-I did not want to hear that lol. Maybe I’ll try eating some berries if I get the craving. The weird thing about berries/fruit is I feel like my blood sugar has raised right after eating it, even more so than a piece of chocolate. Maybe that’s in my head.

        1. I think it might just depend on the person… I am more of the “cold turkey” kind of person, whereas my wife is violently against it, in favor of the gradual solution. I will say that I AM able to change quality better gradually, better than quantity (I.E. raising the % of my chocolate helps me to crave it less than just cutting back on the chocolate I am eating).

          If you prefer the gradual method, try it first, try different angles of it, then try cold turkey. Hope this helps!

    3. I too have a sweet tooth, especially for chocolate. I make it a point to give up chocolate, and then lately sugar, for Lent each year. For some reason (spirituality? I’m not actually Catholic), I can only find the willpower to give up sugar during these 40 days. After that time away, everything tastes way too sweet. The rest of the year I stick with dark chocolate and fruit. And I make it a point to avoid dessert after dinner, including fruit, as much as possible. That evening sweet load does not do me well. After 5 years of this (Lent and restricted sweets), I really find that I no longer can eat milk chocolate or any sugary treat.
      BTW, Trader Joe’s 85% dark is the best stuff ever! (Thanks, Mark. That was your recommendation.) Not chalky and better savored when melted on the tongue; not chewed and swallowed quickly. It has a subtle vanilla bouquet that I love.

    4. Bobbi, I used to make (and eat) a batch of from-scratch brownies, with extra chocolate, every night! It was bear of a habit to kick! First, I tapered. I put aside one brownie a night for a while, til I had a batch saved. Then I ate the saved brownies, not baking a batch that night. Next phase, I put aside two each night, again not baking on the night I ate the saved brownies. And so on. Then I joined an evening class, leaving myself little time for baking OR thinking about it… Good luck!

    5. For me breaking the sugat cravings was a combination of two things. First of all I started drinking kefir several times a day for its various health benefits and found that the sugar cravings began to reduce naturally. After doing that for a while I started cutting out sugar deliberately and found much better success with curbing them with fruit rather than trying to fight it completely. Half an apple or a banana drizzled with just a taste of chocolate syrup if the chocolate craving was very strong. Over time it’s enabled me to be on a lchf diet with very little craving.

  5. Don’t think I could ever eat that much garlic, but love the idea of torching my veggies! And I tend to stay away from the microwave. I don’t think it’s the worst thing, I just generally don’t enjoy anything that is cooked in it. At most I’ll use it for heating something, but can’t even remember the last time I did that.

  6. Yes, it’s hard to trust the microwave. But, as you say, it’s hard to find good evidence against using it. They work well, quickly and consistently. It’s the best way to eat sweet potatoes! I’m sure that somebody will eventually discover that given access to a mirrored box and a quasar, macaques microwave their food as well.

  7. I love your suggestion to eat lots of whole garlic. One of my fav recipes is chicken a la Allium – layer of chicken thighs in a pan, covered by equal parts chopped onion, garlic, and shallots. Not for the faint of heart!

  8. The salt comment struck me, since it is a comment I have been hearing from low-salt-diet proponents for years, and never believed. I have always found salt to enhance flavor, unless it is overdone. I like my vegetables and meats well-salted, and potato chips are about my favorite not-so-primal treat.
    Did any of you (Mark, this includes you and your staff) notice this article in the New York Times, titled “Why Everything We Know About Salt May Be Wrong” ?
    It is VERY interesting. It references two research papers: and
    Bottom line (my own focus and interpretation) is that salt behaves in a more complex way in our system than anyone had thought. It also seems to affect both appetite and energy levels. I will be watching for more from these researchers.
    I also personally believe that real, simple sea salt (which has many different salts, and many different minerals, in it) is a great way to increase the nutrient density of your food. Think about it.

  9. Don’t torch veggies or anything. Get a sous vide. Put a rib roast in it in the morning. Enjoy a wonderful dinner of nutrient dense succulent meat in the evening. It will cure what ails you and kick your sweet chocolate cravings to the curb.

  10. Love how you have an open mind, hinting at having come across structural water. Interesting stuff, Def the next frontier to explore

  11. How do I submit a “Dear Mark” question? I can’t find anywhere on the website. My question is: You often hear how farm raised salmon and non-organic berries may actually be bad for you. When eating out, and wild caught salmon and organic berries aren’t available, should I actually choose something else over them? They are still what I like to eat, but now I’m overly worried about pesticides and bad composition of the fish. Thanks!

    1. The dose makes the poison. If you eat farm raised salmon or non organic fruits once in a while, it won’t have any impact. By the way unfortunately wild salmon might be more polluted than farm raised… There are also farms who do it quite ethically, without overfeeding them with soy… Wild or organic is not always better. Local and small producers are also a good way to go, even if not organic certified.

  12. I love garlic (and onions) so you can be my friend. But other people may not be if they catch a whiff of the resulting breath! Any strategies to get rid of garlic/onion breath quickly?

  13. The butane torch is a seriously good idea! I hate eating cold food (especially meats), so it would be great for when I don’t have access to an oven or grill. Could Mark go into a bit more detail about the process? What do you use to hold the food while torching, or what surface do you have it on?

  14. “I can’t come up with a good, evidence-backed reason not to use the microwave.”
    Neat, me neither haha!

  15. This info just in from a physician with degree in biochemistry and physics:

    “Just a science PSA. Microwaving relaxes plant cell walls and makes nutrients more bioavailable.” Thus easier to digest and absorb.