Dear Mark: Leptin Resets, Cold Thermogenesis, and Safe Starches?

Before we get to the topics du jour I’d like to express my appreciation to everyone that participated in last week’s “Dear Readers” comment board. As I said, Mark’s Daily Apple, my books, and what I do is constantly informed by your thoughts and ideas. In other words, I couldn’t do this without you, so thank you for your feedback.

My team and I have compiled all of your ideas and have begun laying out a plan to give you what you want, and to reach the largest number of people possible. We’ll be checking things off the list in coming months, so stay tuned! Now on to today’s article…

From cruise ships to tweets to ice baths to supposedly hacked social media accounts, Dr. Jack Kruse the man is nothing if not controversial. But what about his ideas – do they have any merit? That’s what many of my readers have been wondering, along with how I feel about them. I’ve remained pretty silent on this matter, because Jack was doing his thing and apparently helping a lot of people in the process. I was doing mine and helping people in my own way. And all was well. Now, though, the questions are coming in droves, and I can’t really ignore them any longer.

“Do I have to sit in ice water to stay healthy?”

“Do I really have to eat 50 to 75 grams of protein for breakfast even if I can’t force it down?”

Etc., etc.

I’ve also included a question about safe starches for good measure. Ready? Let’s go:


What do you think about Jack Kruse’s Leptin Reset or his Cold Thermogenesis protocol? Any merit to them?


Well, let’s look at the Leptin Reset. What does it call for, exactly?

  • A big protein-rich breakfast, at least 50 grams’ worth, but even up to 75 grams.
  • Eat low carb Paleo, especially if you’re really overweight, in which case you should eat very low carb. Increase carbs only if weight loss progresses.
  • Don’t snack, especially late at night. Eat three solid meals.
  • Reduce or eliminate light exposure after sunset.
  • Keep workouts to a minimum, and if you do work out, do it after five.
  • Practice meditation or some other form of mindfulness before bed.

Sound familiar? Other than the emphasis on protein (more later) and the “after five” admonition, I can’t really find too much fault with this approach. It hits all the major points we talk about and have talked about in the past.

That said, my views slightly differ on the importance of protein in the diet. It can be extremely satiating, which is helpful when trying to lose weight and subconsciously curb food intake without obsessing over calories. Anytime you’re trying to stuff yourself with a macronutrient past the point of feeling disgusted with yourself, though, I have a problem. We shouldn’t be doing that. It shouldn’t be necessary. Studies do show that a high-protein breakfast improves weight loss and satiety better than a breakfast of any other macronutrient breakdown, but it should not be continued indefinitely.

I also question whether that amount of protein is really necessary – or even useful – for most people. Thirty grams at a sitting is probably the most your body can deal with. Of course, if you’re legitimately using that protein toward muscle building and repair, have at it. Metabolically healthy, training hard and lifting heavy? Eat to your heart’s content. But if you’re eating protein just to stuff yourself and stay full and satisfy a requirement you feel bound to, you’re going to waste a lot of it. As I’ve said before, I’m trying to minimize my use of glucose, whether exogenous or endogenously produced. If I’m eating so much protein that the excess is being converted to glucose, I’m not really minimizing it, am I?

What about the Cold Thermogenesis stuff?

I like the idea of using cold water as a hormetic stressor, and I even did a post on the benefits of cold water immersion back in 2008. Throughout the year, I take frequent cold plunges myself in my pool, which reaches the mid 50s in winter. I’ve been doing it for years now after a training buddy of mine turned me onto it. I use it for recovery after a training session, and sometimes just to wake up and feel energized in the middle of the day. My sessions typically last about five or ten minutes, but I’ve gone as long as thirty. What do I notice since doing cold plunges?

  • Enhanced recovery from particularly vigorous training or playing. I’m ready to go the next day, rather than feeling beat-up and worn down.
  • Reduced DOMS, even after a heavy day.
  • Less pseudo-arthritic pain in my lower body joints. My arthritis pretty much disappeared since going Primal and giving up endurance athletics, but once in awhile I’d still get a few lingering, worrisome pains. No more.

I’ve never had much fat to lose, so that’s never been a determining factor for me. I do have a concern, though, with the concept of regular prolonged immersions and cold “adaptation” for people trying to lose body fat. One of the epigenetic adaptations to regular long exposures to cold is an increase in subcutaneous fat, as the body attempts to prevent heat loss by building a layer of insulation (fat). This happens often in marathon swimmers who train in cold water. Even non-elite pool swimmers who put in huge yardage tend to have this layer. The other concern is what seems to be an increase in appetite after long exposures to cold (after burning all those calories shivering). That would seem counterproductive – and uncomfortable.

Dr. Kruse is enthusiastic, and, judging from his followers and his monster thread on my forum, many people have found success using his methods. I’ve got nothing against the man. I just want people reading his stuff to be cautious. Take cold plunges, absolutely, but be careful with the two-hour ice water baths. Be wary of some of the more fantastical claims, like improving your lifting numbers by 150 pounds just by sitting in an ice bath, getting “shredded” just from cold water exposure, or falling asleep in a bathtub full of ice for ten hours being safe.

If you’re really interested in cold water therapy, I’d look to Ray Cronise, the NASA scientist who helped Tim Ferriss on the cold water immersion section in the Four Hour Body book. He’s far more measured in his claims and recommendations. According to Cronise, “cool water” is very effective for weight loss, not just freezing cold water, and you don’t have to go numb for days on end to derive benefits from it. Another place to look for inspiration is Richard Nikoley of Free the Animal, who’s been experimenting with cold water exposure for a few years now. Check out Richard’s post from a few weeks’ back where Cronise participates; it’s pretty interesting. If you want to try this out without getting too obsessive or buying any special equipment, you could do the occasional cold shower thing, maybe, but my advice is to just go for a swim in a cool – or even cold – body of water. A pool, a river, a lake, the ocean, whatever. And yes, swim. Don’t sit and stew. Just do some laps, see how many times you can swim underwater from end to end without taking a breath, play Marco Polo, play water polo, get three more people in there for some chicken fights.

Hey Mark,

Safe starches. Are they really safe?


There are certainly safer starches. Things like white rice, yams, sweet potatoes, potatoes, and any other starchy root, tuber, or vegetable that are relatively free of food toxins (gluten and related proteins, grain and legume lectins, etc) are far better choices than pasta, bread, muffins, and pizza. But that’s not to say that everyone should be making those choices, day in, day out.

In general, I’m trying to burn as little glucose as possible. That’s not to say I’m always full-blown ketogenic. I tailor my carb intake to my activity level and my natural inclinations and desires. If I’m playing a lot of Ultimate or going through one of my periodical (but rare) two week stretches of heavy lifting and sprinting a ton, I’ll generally eat a few more sweet potatoes than usual and opt for nigiri over straight sashimi at the sushi spot. But that’s not very often. Most of the time, I stay active, but I don’t go nuts. I’m mostly burning fat, walking a lot, staying on my feet, maintaining a constant level of activity, and punctuating my days with brief spurts of intense activity. I’m not intent on increasing my work capacity, my muscle endurance, nor my ability to take a ton of pain and come out on top – even though I do pretty well when I try something (like Ultimate) that calls for that stuff. So I rarely feel the need to “carb-up.”

The common factor among all these scenarios is that I let my needs dictate my consumption. I call carbs “the elective macronutrient.”  If I need the safe starches to perform better at what I want to do, I’ll eat them. If delicious food that happens to be higher in carbs is in season, I’ll eat some. Just last week, I spied a flat of organic Gavota strawberries at peak ripeness on my way to pick up pastured eggs at the farmers’ market and felt like eating a bunch. So I did. I bought that flat and we went through it in a few days. Was it a “lot” of carbs? Sure, but they were delicious, the weather is really warming up, and they were in season. It just felt right. And because my glycogen stores are generally light, I’m sure I simply topped them off and then burned through most of it doing HIIT the next couple of days.

That’s how I think we should approach safe starches. If it feels right, if your body seems to want it, and you’re going to use those carbs, then go for it. If not, don’t. You’ll probably find that 150 grams of carbs gives a surprising amount of leeway. You’re still low-carb and relying on fat for the bulk of your energy needs, but you’re not in full blown ketosis all the time, which can be limiting (but useful as a therapeutic tool). And if it’s not enough, if you insist on hitting the training a little harder (than I’d like) some days, try a cyclic low-carb approach. Eat low-carb on rest days, higher-carb on training days. A “carb refeed” might be warranted in this case, and it would allow you to still be in fat-burning mode most of the time.

But ultimately, I think we should be focusing on becoming fat-burning beasts, running on clean plentiful fuel, enjoying steady even energy, and avoiding a lifetime of sugar-burning. If that means limiting the types of chronic high-intensity, high-volume training that necessitates eating loads of safe starches, so be it. That’s what I’ve chosen to do for the rest of my time here, and it seems to be working pretty well. I’m rarely ketotic, since I like my veggies and berries as much as anyone, but when I do slip into ketosis, it’s not a struggle and there are no side effects. The machinery is already in place and fully operational.

Well, that’s my take on it all. What’s yours?

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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