Dear Mark: Mortality Risk, Fish Heads, Metformin and Exercise, and Cooking Frozen Veggies

For today’s edition of Dear Mark, I’m answering four questions from readers. First, what does an “increased risk of mortality” actually mean if everyone’s going to die in the end? Second, what makes fish heads so delicious and nutritious? Third, what is the relationship between metformin and exercise? And finally, how do you prevent frozen vegetables from getting all mushy when you cook them?

Let’s go:

Hey Mark,
In regards to the “garbage” meat study, how does relative versus absolute risk work? Does 3% increased risk of dying mean that if my chance of dying this year based on mortality tables is say, 10%, if I eat red meat my chance of dying is 10.3%?

Yep, you got it. It means that for the duration of the study, the subjects eating more meat had a 3% higher risk of dying. Some people lived, some died.

It’s not open-ended, though (because as everyone knows, everyone dies someday). The risk is confined to the duration of the study.

Since you mentioned eating whole organisms, I was wondering if there are any specific nutritional benefits to fish heads? I can get really cheap great fresh fish heads from my fishmonger which are fantastic steamed, and I’m curious as to their nutritional value. I can’t get much data on the heads particularly—surely the eyes and fish brain must have some unique stats and benefits? And while I’m at it… could I overdose on them? How much would be too much too consume each week in your opinion?

Grizzlies know the deal. During salmon season, they camp out on the river and snag salmon on their way to spawn. They’ll often eat the brain, eyes, roe, and belly, then toss the rest. They’ll go through dozens of them in a day, focusing only on the head and belly. Why? What’s good about the head?

Let me tell you about the beauty of the fish head.

The brain: A cow brain is incredibly rich in omega-3s, especially DHA. A salmon brain is INSANELY rich in omega-3s. Not only that, they are in phospholipid form, a structure that’s far more bioavailable than other types of fatty acids. The roe of a salmon is another excellent source of phospholipid-bound omega-3s.

The eyes: Eyes in general (like yours) are also loaded with DHA. A fish eye will have even more.

But a fish head is also delicious, not just nutritious (although the two often pair up, especially when you’re talking about whole Primal foods).

You’ve got the collar, that meaty ring of flesh and skin. Any Japanese spot worth its salt will have grilled yellowtail (hamachi kama) or salmon collar on their menu. Get it—it’s a great deal and a marriage of meat, skin, and collagen.

You’ve got the cheeks, unctuous bits of tender fish meat.

You’ve got the skin, which is incredibly fatty and collagenous.

You’ve got the brain, whose nutritious merits I’ve extolled. The brain is mild.

The eyes are pretty good, too. A bit chewy with a large deposit of collagen.

And if you’re willing to get messy, you can just dissect the head and look for the meat, fat, and skin. A good-sized wild salmon head roasted in the oven with just some salt and pepper is a solid meal that leaves you incredibly satiated because it’s so nutrient-dense.

Peter Attia has noted that in healthy people (non T2D, no metabolic issues) metformin blunts the benefits of exercise, especially the Primal type of low-intensity training. It therefore may decrease mitochondrial function. In other words, the more healthy you are, the less helpful metformin may be and can possibly make you less healthy, though that is not completely confirmed. Basically, if you’re healthy and Primal and do some intermittent fasting here and there, you may at best not benefit by taking metformin. See his podcast with Iñigo San Millán for more details.

There’s definitely something to this.

According to an interesting study in older adults without chronic disease, metformin actually inhibits mitochondrial adaptations to aerobic training. Exercising increases insulin sensitivity, unless you take metformin. Exercises improves mitochondrial respiration in the muscles, unless you take metformin.

It also appears to blunt the anabolic response to strength training in older men. In this study, those taking metformin and training saw less muscle gain than those training and taking a placebo. If true, this is a big blow against metformin supplementation for this population. The older you are, the more muscle you need to stay healthy and avoid morbidity. Every gram of muscle is crucial.

And it’s not just in “healthy” people. For instance, type 2 diabetics who take metformin and exercise regularly have worse glucose control than those who do neither. The authors of the study suggest that it may be “too much of a good thing”—that trying to stack metformin and exercise leads to a counter-signal, reversing the benefits.

Metformin might make exercise feel harder. Of course, it also increases fat-burning during exercise, and if you’re not used to burning fat during exercise, a sudden shift in that direction might  make your workout feel harder.

There’s a confusing relationship between exercise and metformin for sure.

I’m not sure what to think about metformin, to be honest. Another interesting study came out in the middle of last year comparing metformin alone to an intensive lifestyle modification program for weight loss. What happened?

Around 29% of the subjects who took metformin lost at least 5% of their weight in the first year. Almost 65% of the subjects who underwent the lifestyle program lost at least 5% of their weight.

Then, they followed up to see who’d kept the weight off from year 6 to year 15.

The metformin group won this one; 6.2% of that group maintained the weight loss while just 3.7% of the lifestyle group did.

So metformin can definitely help your average person who can’t (or won’t) maintain the lifestyle changes necessary to make a real difference. But if you can maintain the lifestyle that brings so much initial success—the diet, the training, the sleep, and everything else—it’s far superior than any pill you can take.

I would really appreciate any suggestions on how to cook frozen vegetables to make them taste delicious and crisp rather than soggy and limp… many thanks.

The trick is to use high heat. Whether you’re going to roast your veggies in the oven or cook them in a pan, you must get everything good and hot before introducing the vegetables. That means preheating the pan with fat (avocado oil works great here, obviously) before you add the vegetables. Cast iron can help here, as it really gets hot and holds that heat.

If you’re using the oven, hit 450°F or so. If you’re using the stove, go medium-high to high heat.

Also, don’t crowd the pan and cool things down by overfilling with frozen plant matter. You want room between each piece of vegetable. You want them to caramelize and crisp, not steam.

Thanks for reading, everyone. Take care, ask any followups you might have, and have a great day!

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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12 thoughts on “Dear Mark: Mortality Risk, Fish Heads, Metformin and Exercise, and Cooking Frozen Veggies”

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  1. Fish: I love fish skin, and my husband doesn’t like it, so I generally get a double dose. Whole foods has started carrying whole fish, as in, not even gutted, recently. I love it because I get to rescue the fish liver. I only eat that cooked though, too much chance of wormies. Fish stock is incredible. The trick to it is to cook it for a short time, the opposite of bone broth from cow bones. It’s not that it will be bitter (I tried the long cooking, it tasted fine), it’s that the fish gelatin breaks down under boiling. So the liquid is full of gelatin, but it’s not going to gel because it broke down. It’s not harmful to the nutrition I don’t think, but it helps the efficiency in the kitchen to not cook it too long. I add a strip of Kombu seaweed and some salt and a bit of rice vinegar. I”m a huge fan of fish broth. I don’t cook the liver in the broth though.

    The liver gets cooked in a bit of milk, cooled, shredded and the whole thing added to a bit of canned tunafish, then it tops a bit of bread or cracker. I try not to make a lot of it as I’m still getting used to the taste. Onion cups would be a good “cracker” alternative for this. I don’t know why I didn’t think of that until just now.

    I’ve never been able to eat salmon roe. Looks so pretty, but every time I open it it stinks so bad. I’ve stopped spending big bucks on it.

  2. Another trick for cooking frozen veggies is… air fry them! I’ve had good luck with much tastier, crunchier veggies that way. Coat them in a spritz of avocado oil, fry away…

  3. Loved this dear Mark, one of the most helpful I’ve ever read!

    Appreciate the frozen veggie cooking tips, with kids and a full time job frozen vegetables by the end of the week are usually my go to. Would love if you incorporated them into some of your weekly recipes too on occasion.

    Really interesting about fish heads also, will have to look into acquiring some very soon for a super nutritional boost!

    Since you delve into fish heads what about large fish roe? I often see John Dory roe and fresh mullet roe on sale where I live but haven’t been brave enough to buy any. Mostly as I don’t know how to cook it. They are huge and look a little like an oddly coloured bran. Any special benefits? And any cooking tips?

    Also my husband really can’t stomach fat very well. He genuinely hates the taste and sensation- plus he says it makes him feel slow and heavy. He’s been that way since a child. He’s much better with white fish and lean cuts of meat, plus some primal carbs like sweet potato, potato, pumpkin, plus lots of veggies and fruit. He eats plenty of oysters, mussels, scallops and lean chicken liver every month and is very slim and active but I worry about fat soluble vitamins and the other great benefits of good fats. Should I be concerned? And what would you recommend to add to his diet if so?

    Cheers Mark, and please never stop dear Mark- I always really enjoy these posts ??

    1. I have 2 boys aged 8 and 11 who are the same way as your husband any fat on meat they hate, added oil or butter even! No Avocado either, they just do not like it. They eat plenty of fruit, vegetables (no oil or butter), meat without the fat, and potato’s plus other safe starches, and they eat almost any seafood you put in front of them, but the no fat thing worries me at times. Would love to hear Mark’s take on this.

      1. My kids are the same. The only high fat (and its not really high fat) thing I can get in them is the occasional glass of whole Jersey milk. They hate oil, butter, fatty meat, avocado, mayo, anything creamy (aside from the minimal milk) It makes me anxious they aren’t getting fat so liable vitamins but I’m inclined to trust their instincts. They eat plenty of potatoes and sweet potatoes, fruit, some veggies and enough lean protein to get by for now. Would still love to hear Mark’s take on this though, are some people just naturally more suited to a low fat diet? Outliers perhaps?

  4. We use frozen veg a lot. And, yes, high heat. Tonight did stir fry with mostly frozen stir fry mix. Some fresh broccoli and onions, and chicken thighs. Was good.
    Fish heads? Nope!

  5. Cooking Frozen Veggies – nothing beats a Pressure Cooker
    It’s fast & they will come out as crisp & bright as fresh.
    Don’t overcook & don’t use too much water

  6. I prefer fresh vegetables because the texture is better. The flavor usually is too. About the only frozen ones I regularly buy are peas and various types of greens (turnip greens, collards, spinach, etc.).

    In my area you usually can’t find fresh unshelled peas. Sometimes the farmers’ markets have them in the summertime, but the grocery stores don’t carry them. That’s unfortunate because garden-fresh peas, steamed and buttered, are a real treat.

    As for fish heads, nah. I’ll pass. There’s something about fish heads–and fish skin–that I find a little too off-putting.

  7. The blog on Metforman was definitely beneficial. I am new on keto diet as of April 2019 and had trouble staying on the diet but now 11 months later I am keto adapted and doing better with exercise as well, country dancing, pickle ball and 4 sets of 15 squats a day. Your blog has motivated me to stay on my Metforman which was ordered for inflammation not diabetes , until I am completely compliant with the diet and exercise and have attained a normal weight. Then I will start weaning Off of it. I am 64 years old. My top weight was 265 and I now weigh 188 with a goal of 150.