Dear Mark: Acrylamide, Sprint Alternatives, Gynoid Fat, and Adult Bed Sharing

French FriesIn this week’s edition of Dear Mark, I’ll be covering three wide-ranging topics. First is acrylamide, the french fry toxin, the coffee carcinogen, the rat destroyer. It appears in almost every starchy item cooked or roasted at high heat, and it’s classified as a carcinogen. What do we do about it? Do we even have to worry about it? Next up are sprint alternatives for the person who loves to runny really fast every once in awhile but has a herniated disk that becomes aggravated shortly after said sprint. Sprinting is an important, beneficial activity, so long as you can do it pain and injury free, so I try to come up with a few worthy options. Then, I offer some advice to a man with gynoid – or lower body/hip/thigh – fat, most of which hinge on my suspicion that he’s low in free testosterone. Finally, I discuss the benefits – and drawbacks – of co-sleeping with your adult partner.

Let’s go:

So recently I was in Starbucks and it seems a law has been passed in San Diego where mandatory posted warnings against the detriments of Acrylamide, a chemical that is created when a food is baked or roasted that is highly toxic and carcinogenic, must be presented. Are you familiar with Acrylamide and how would you suggest we go about avoiding it?


Acrylamide is a carcinogen that forms when starches are heated above 250 ºF, particularly when “browning” occurs. Boiling and steaming do not reach 250 degrees and thus do not form acrylamide. The easiest way to avoid acrylamide is to avoid the foods highest in it.

As you saw in the link, restaurant and store-bought french fries, chips, crackers, baked goods, and other high-heat starchy fare are uniformly high in acrylamide, while meats and most vegetables are extremely low. Bread, particularly crusty, well-toasted bread, is a big offender as well. Coffee’s another one (hence the message in Starbucks). Homemade foods can also be high in acrylamide, but they don’t have to be. Provided you take certain precautionary steps, you can enjoy your sweet potatoes without worry.

Steaming or boiling are good options. Braising should be better than baking, roasting, or frying, but there’s still the chance for some acrylamide formation.

Certain “dietary plant materials,” like clove extract and grape polyphenols, are actually able to inhibit acrylamide formation during the cooking of starches. Rosemary, too, can reduce it. I’d imagine other antioxidant-rich plants, herbs, and extracts would have similarly inhibitory effects. Next time you make sweet potato chips in the oven, consider including some herbs and spices in the mix.

Fermentation reduces acrylamide fermentation. This may not matter much to you (who ferments french fries, and how do you even do that?), but if you have any bread eating friends or family, try convincing them to make the move to real sourdough (or away from grains altogether).

It’s also worth noting that man is the cooking animal. We’ve been subjecting our food to fire for hundreds of thousands of years (at least), and it’s likely we’ve developed some endogenous acrylamide detoxification pathways along the way. Most human studies have failed to find a connection between dietary acrylamide and rates of cancer (except for kidney cancer and multiple myeloma). That’s not to suggest it’s harmless. It’s that every (cooked food) diet is going to include some acrylamide. It’s unavoidable. The key, I think, is to avoid or minimize eating the most egregious sources. Don’t eat fries every day, for example – even if they’re cooked in pastured duck fat.


I’ve, in the last few weeks, gone totally paleo. I feel better, look better, and my back hurts a little less than it did. However, I do have a herniated disk in my back and as much as I’d love to sprint ( I actually love running and go to the gym daily), it makes my back pain way worse afterward. Any suggestions on cardio that will be similar to sprinting or a way I can run with my bad back?


If I had to guess, the reason why sprinting aggravates your back is the impact of landing. When you sprint, you’re hitting the ground pretty dang hard, and the shock can reverberate throughout your body. Any weak link – like a herniated disk – will feel the brunt of the effects. Here are my tips:

1. Sprint uphill. When sprinting uphill, your feet don’t “fall as far” as when you’re sprinting on a flat surface, and so the impact is reduced.

2. Check your sprinting form. Make sure you’re landing on the forefoot-to-midfoot, rather than on the heel. Allow your heel to come down into contact with the ground, but only after you’ve established contact with the fore/midfoot. You also want to maintain good posture when running. If you let your shoulders internally rotate and your head dip forward, you’ll lose postural integrity and risk incurring pain. Also, when you run, your head shouldn’t be bobbing up and down. Film yourself, or have someone watch when you run and note whether or not your head bobs and your posture fails.

3. Try an alternate mode of transportation. Cycling, swimming, running in water, even crawling can reduce the impact on your back. I love a good stationary cycle sprint myself.

4. Find a full body exercise, preferably involving weights, that you can perform safely at a high intensity with good form without pain. Then, do that exercise at a high intensity for short, repeated bursts – maybe 5-10 rep sets with short rest periods.

5. Don’t sprint. If nothing’s helping, avoid the activities that cause pain. You want to heal, and pain is your body’s way of telling you that damage is (or soon will be) being done.

Hi Mark,

Thanks to supportive friends and the resources you and others have provided online, I’ve been following the paleo lifestyle for around a year now. So first, thank you for everything you’ve already contributed to the world.

As I’ve gone down the paleo path, to measure progress, I got a DexaFit body scan. Part of the result showed that I store an abnormally high proportion of my body fat in my gynoid region (waste/hips/thighs). For additional context, growing up, I was a “fat” kid until I was about 14, when I started exercising more / eating less.

All this got me wondering – is my body shape today due exclusively to my genetic make-up (nature) or the actions I’ve taken in life (nurture)? Is it some combination favoring one or the other? At what point are we “locked-in”, where our actions no longer have an impact?

I wonder, if I hadn’t been a “fat” kid growing up, maybe I’d look different today, even eating the same things and following the same workout regimen. Through the years, I’ve heard miscellaneous “facts” like weightlifting too early stunts growth, there’s some belly fat you can’t lose after a certain age, etc.

Thank you for your insight! I really appreciate your expertise on this.


As with just about everything, it’s both nature and nurture. That is, environment interacts with genetics to produce the people we become, with all our health conditions, quirks, foibles, flaws, and strengths. The black and white dichotomy between nature and nurture is pure silliness (except for maybe something like eye color or hair color) that no one really takes seriously anymore. It’s (almost always) both.

On to your specific issue. For you, a male with a more “feminine” pattern of fat deposition, I would suspect low testosterone levels. A recent study found that patients with hypogonadism, characterized by chronic testosterone deficiency, stored dietary and free fatty acids primarily in the hips and thighs. In the leg-and-thigh adipose tissue of the low-testosterone group, acyl-CoA-synthetase (which is partially responsible for fat deposition) activity was greater. Another study confirms that when it comes to body fat distribution, genetics have a greater role in women, while environment is the primary determining factor for how fat is distributed in men. Luckily for you, you can control your environment. You can affect how much testosterone you produce, often without resorting to hormone replacement creams or injections or anything like that.

Certain nutrients help restore and maintain testosterone productions. Eat the foods that contain them. Supplement if you can’t or won’t eat the foods.

  • Magnesium – Eat leafy greens, almonds, halibut. Take epsom salt baths, apply magnesium oil transdermally, take chelated magnesium supplements.
  • Selenium – Eat Brazil nuts, kidneys, wild fish.
  • Zinc – Eat red meat, oysters.
  • Cholesterol – Eat brains, egg yolks, liver. We make testosterone out of cholesterol.
  • Fat – Eat fat, especially saturated and monounsaturated fats. One study found that olive oil (monounsaturated) and coconut oil (saturated) enhanced the conversion of cholesterol into testosterone, beating out grapeseed and soybean oils.
  • Vitamin D – Get sun, eat wild fish, take D3 supplements.

You’ll also want to make some lifestyle changes, if you haven’t already.

  • Get enough sleep. A lack of sleep dramatically reduces testosterone in young men. Similar relationships between sleep quality and testosterone are found in older men, too.
  • Reduce stress, or find ways to deal with it. Cortisol “opposes” testosterone, so an imbalanced or excessive cortisol rhythm will hamper your production of testosterone.
  • Meditate. Meditation is relaxing by definition, and one study even shows it reduces the cortisol:testosterone ratio.
  • Try breathing exercises. I talked about belly breathing a while back, and you might want to try that out.
  • Get a massage.

Even if these tips don’t result in reduced gynoid fat (I bet they will, though), they will result in an improved, more enjoyable life and diet. You might also want to get your free testosterone tested, just to make sure that low T is indeed your problem. Good luck!

Hi Mark,

Can you tell us your opinion about adults (partners) sleeping together? Is this a primal behaviour? Is sleeping on your own more restful?


It all depends, of course. There’s no one single absolute overarching answer.

If your partner snores to the point of keeping you awake, sleeping separate will get you more sleep and is probably going to be more restful and therefore more healthy.

If your partner has the jimmy legs, and the notion of a bony knee or ankle bone digging into the small of your back makes you unhappy, sleeping separate is going to be more restful.

If your partner has obstructive sleep apnea, you may have disturbed sleep and increased musculoskeletal pain.

However, recent research indicates that sleeping with a partner lowers cortisol (reducing stress), increases oxytocin (increasing bonding and closeness), and lowers inflammatory cytokines. If you’re fighting with that partner over conflicting sleeping habits, of course, you’ll probably be stressed out (cortisol goes up), be unwilling to touch each other (lowering oxytocin), and you probably won’t get the anti-inflammatory benefits.

Harmonious co-sleeping with a partner is more restful. Argumentative co-sleeping is not.

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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