By Peter Park



I have a new book out! It’s called, “Rebound: Regain Strength, Move Effortlessly, Live Life Without Limits.” The book’s an ode to my “Second Journey” clients, folks who used to “just do it” – play tennis, run marathons, jump out of airplanes, dive for abalone – but aren’t getting it done anymore. Their Second Journey is about getting fit again so they can do all those things again. Go to if you want to read more about it.

One of the things I talk about in “Rebound” is that throughout my career as a strength and conditioning coach I’ve acted as my clients’ personal science project. Their guinea pig. Whenever I hear of anything new and promising in the fitness or nutrition world, I learn everything I can about it, experiment on myself, and if it passes muster, I integrate it into my routine. And when I have it down, I introduce it into my clients’ routine as well. A good example of this guinea pig paradigm is kettlebells. When they first came to the States, I was intrigued, so I went straight to the godfather of kettlebells himself, Pavel Tsatsouline and learned everything I could from him. (We still see each other frequently and I’m still learning from him and his StrongFirst organization.) And then I brought back what Pavel taught me to my gym, Platinum Fitness, where I practiced get-ups, swings, rows and dozens of other kettlebell exercises. And after I mastered them, I integrated kettlebell training into my own routine and then my clients’. So the paradigm goes.

Last year, some of my clients asked me about a popular diet that, until recently, was trending mostly with endurance athletes. It’s called the ketogenic diet, a mostly fat (80%), moderate amount of protein (15%) and almost no carbs (50 grams or less per day) diet that converts the body into a fat-burning machine.

Going keto is popular in endurance sports, because our human fuel tanks have the capacity to store far more fat energy than our glycogen (sugar) ones. That means (at least in theory) that while going keto, athletes can go longer and farther without refueling. And, fat is a more stable source of energy than sugar, so those athletes don’t experience the extreme highs and lows sugar-sourced energy can cause during training and races. So for you triathletes, ultra-runners, and long-haul cyclists, going keto might very well be an efficient way for you to fuel for your sport.

But go in a bookstore (virtual or brick and mortar) these days and you’ll see that going keto has now become a mainstream weight loss diet as well. Wait, eating loads of bacon can help the average Second Journey guy or gal lose fat? First, not loads. Second, I’m talking about mostly healthy fats. Thirdly, actually, yes, going keto can help you lose weight, especially if you train long and slow, or, crazy sounding as it is, if you don’t train much at all. Because fat burning happens at lower levels of exertion (as opposed to high-intensity or interval style training.) So if you’re eating a mostly-fats diet even if you sit on your ass all day, the few calories you do burn are likely to be from the very fat calories – the avocado, egg, and spinach cooked in olive oil – that you ate that morning. Sounds almost too good to be true? That’s what my clients wanted to know. And so did I. But I also wondered if going keto is a healthy way to live over a lifetime. Consuming all that fat, even so-called “healthy fats”, is a pretty extreme way to eat, so before I advised any of my clients to try it, I took on the job of becoming their ketogenic guinea pig. And for ten months I went total keto.

(Note: One man’s 10-month journey hardly constitutes a widely tested, long-term scientific study. Nonetheless, I think the results here have value, especially for Second Journey folks like me.)

So what did going keto look like for me? I ate a lot of eggs, veggies cooked in coconut, olive, or avocado oil. I ate nuts, moderate amounts of red meat, chicken, fish, avocado, cheese, butter, and I spilled cream into my coffee. I did eat bacon, I ate sausage, not tons, only occasionally. (Going keto isn’t a license to be a fat-gorging pig.) Those are the foods I added to my diet. But equally as important, what did I subtract from it? Almost all fruit (because of sugar), some vegetables that are higher in sugar like beets and carrots. And I slashed and burned brown rice and sweet potatoes out of my food landscape. In other words, almost anything containing fiber was jettisoned. (As I said, it’s an extreme way of eating.) So how did it go?

What I really liked about going keto is I sometimes struggle to find the time to eat breakfast and lunch during my busy day, but the ketogenic diet is so dense with fat that I could fuel myself in the morning – on, say, a three-egg omelet with veggies, avocado, goat cheese, maybe a few pieces of bacon, some heavy cream in my coffee – and I didn’t have to eat again till dinner. I felt satiated all day. And fat really is a stable source of energy. I didn’t find my energy levels dipping in the afternoons or find myself craving junk food fixes.

And I lost a couple of pounds that I didn’t really need to lose. My body fat went down to five percent. I looked pretty ripped!



As for my performance, as expected when I stuck to longer and lower intensity exercise – fat burning – I did very well. On three, four or more-hour bike rides, I didn’t have to eat a bite. And longer, lower-intensity workouts in the gym, same thing, I felt great.

But when I did high-intensity interval training, with very little glycogen in my tank, I’d eventually hit the wall. And in the weight room, during kettlebell complexes or quick-paced circuit/cardio training, I got fatigued, and I struggled to finish my sets or had to use lighter weights to finish. Or, more typically, I gutted it out and paid the price later (fatigue and sluggish recovery.) Bottom line, over those ten months of going keto, I lost power and strength.  

As for my blood work, that’s where the sticker shock really hit hard. After ten months of eating all that fat, and cutting out fruit and fiber, my total cholesterol jumped from 170 to 280. (Under 200 is considered good, 239 and above is high risk for heart disease.) And my blood work showed that I’d developed hypothyroidism. My body wasn’t producing enough thyroid hormone and that was affecting my metabolism.

After I got the results, I talked to a lot of people, mostly athletes, who’ve gone keto and whose cholesterol levels have remained stable. So not everyone has had the same negative results as me. But some folks I talked to had their cholesterol levels skyrocket just like mine. Pretty confusing, huh?

So amid the contradictory results, what do I recommend to my clients? First, if they want to try going keto, they should monitor their blood, so they know the effects eating all that fat is having on them. Second, maybe a good way to use the ketogenic diet is to marry it with your training. Spend a few months going longer, slower, building a strong base while eating ketogenic. Then go back to interval training and add back the carbs you’re going to need to fuel you through it.

As for me, my going keto experiment was over because I was kind of freaked out. Me and my heart have a history (notice the scar on my chest in the cover photo?) And now another potential threat was at my heart’s door. So once again I made a radical change in my diet. I became a guinea pig all over again, but this time on behalf of my clients who have high cholesterol. What diet did I switch to? I’ll tell you in my next post but give you a hint now: It rhymes with wegan. And the results surprised the hell out of me.


About Peter Park

Peter Park is a former Ironman triathlete, ultramarathon runner, and has been a strength and conditioning coach for twenty-eight years and is owner of Platinum Fitness Summerland. He’s also the co-author of “Rebound: Regain Strength, Move Effortlessly, Live Life Without Limits,” and “Foundation: Redefine Your Core, Conquer Back Pain, and Move with Confidence.” Peter lives in Santa Barbara with his wife, Kelly, and two sons, Hayden and Carter.



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