The 'Peter Attia' Approach to Dieting for Endurance Athletes - Part II

In Part I of this blog post , I outlined the background information on Dr Peter Attia, detailing Peter’s individualization approach to diets, and the importance of fat oxidation for endurance performance. Reading the first post provides important context for understanding the basis of the forthcoming examples and recommendations.

Reading the first post provides important context for understanding the basis of the forthcoming examples and recommendations. As I mentioned in the first post, please note that while Peter Attia is fine with me trying to tackle the topic, it does not imply his endorsement of the approaches in this article as they are my own.

Continuing on from my first continuous blood glucose meter (CGM) example, my next case is from the lab, where I was volunteering for a study and asked to do a maximal volume of oxygen uptake (VO2max) test. In this test, the power ramps up quickly to determine my peak aerobic power output along with my VO2max. Prior to this, I had done a steady state test to determine my fat and carbohydrate oxidation rates. For the short 14 min test (only HR shown), what is interesting was that after I was finished, my blood glucose spiked to 8.9 mmol/L, which is a high number for me, and took an hour to get back down to baseline. This finding brought to light, for me, the impact of high-intensity exercise. Imagine the situation where you were always training hard, coupled with other lifestyle factors known to raise blood glucose. The high-intensity exercise could potentially be adding to the problem rather than being a healthy solution. I’ve written about this issue in a prior TrainingPeaks blog post. High-intensity training is still important, but I suppose balance is the key.

Stress comes in many forms, not just high-intensity exercise, but also due to poor sleep, and the self-imposed stress we inflict on ourselves in today’s world of pinging Emails and incessant social media updates following us everywhere we go with our digital devices. Peter’s reported on the impact of stress in his podcasts, where despite keeping his glucose low during the day, he can still experience high levels of blood glucose in the evening in line with stressful situations occurring in his daily life. Likewise, I could show another CGM trace with nearly the identical response to my VO2max test, but where the rise in glucose involved no exercise or diet manipulation whatsoever, but simply reading an Email that burned. But each situation shares a common cause, with the stress hormone cortisol most likely to blame. Thus, to combat against these environmental stressors that affect us, and in the name of maximizing fat oxidation for performance and longevity, Peter recommends practicing some form of meditation, an idea which was once dismissed by many as being a bit 'out there', but has gained greater traction in the science realm as the benefits are reliably proven. From personal experience, low-key meditation is something that’s certainly helped me control my response to stressful situations and improved my sleep.

Finally, I’ll share a nutrition example from my colleague Dr. Dan Plews. In this example, The Plews ate what we might consider to be a delicious, healthy pear at about 11am, during work hours. We were surprised how high this spiked his glucose levels (6.7 mmol/L) for an hour before his lunchtime run (70 min), which worked to return his glucose levels back to normal. Note the response of his pear in contrast his earlier morning LCHF breakfast (6:45am) that did very little to impact his glucose level.

Alternatively, take again the example of The Plews during a 7-hour training ride we did in the Swiss Alps, with a clear break in the middle where we enjoyed a relatively high carbohydrate meal. In this situation however, where a high workload preceded the meal (note the 42 min climb at 300 W just prior), there’s no noticeable impact on his blood glucose level. Thus, timing is everything. You can ultimately cheat the system if you know how it works. Additionally, perhaps this is how professional endurance athletes, some known to train 35-40 h, can be successful on high carbohydrate diets. However, we believe that it can be done successfully on a much lower training load when proper attention is paid to some of these principles.

As mentioned, everyone’s an individual, but here are a few key learnings from the N=1 data shown before getting back to Peter.

if fat oxidation is important, we should try to keep blood insulin (proxy glucose) relatively low throughout the day,
we can exercise at surprisingly low blood glucose levels if we are fat-adapted,
stress, in many forms, including high-intensity exercise, poor sleep and even nasty Emails, can raise blood glucose levels; heart rate variability can additionally be an easy measurement to monitor in this regard,
even so-called healthy foods such as fruit can impact our blood glucose levels in certain states,
higher-carbohydrate feedings are tolerable from a blood glucose (proxy insulin) situation where you’ve already exercised,
high-intensity exercise is attainable on an LCHF diet (ketoadapted state).

The Peter Attia Approach to Diet for Endurance Athletes

So how does this information affect us? And how does it relate to the Peter Attia approach to dieting for endurance (and longevity)? As Dr. Attia has said, at least for athletes 40 years of age or older, it's a diet that keeps insulin low (along with some other biochemical markers you can learn about by following Peter; IGF, MTOR1, RAS, with AMPk high). The optimal fraction of these molecules will be different for each of us. For Peter, someone who is mildly insulin-resistant like myself, it winds up being a diet that is about 20% carbohydrate, 20% protein and 60% fat. Importantly, he recommends a diet that keeps your average blood glucose low, without major spikes throughout the day (or evening). He also recommends protein to be just high enough to maintain your muscle mass, but not any higher. The balance of the diet should be in the form of healthy fats, which he says is the thing people seem to find most challenging. To keep tabs on the quantities of these macronutrients in your diet, I recommend using a new free smartphone app called Senza.

To finish, Peter’s approach has been revolutionary for my own health and performance, as well as those of the athletes that The Plews and I coach. Thus, we value Peter’s leadership in the area. Of note, a couple of our elite male athletes, Kyle Buckingham and Jan van Berkel recently underwent a 180 degree flip of their diets using these principles, in concert with personal best performances at the recent South African Ironman and remarkable changes in markers of health documented here.

I’ll be presenting on these topics, as well as the information from my first blog post, at the upcoming Endurance Coaching Summit.

Key points:

Fat burning is important. To maximize it, aim to keep blood glucose (proxy insulin) relatively low throughout the day.
We’re all individuals, so find out where your glucose levels sit throughout the day by getting a hold of a CGM. If that’s not available, a morning fasted blood glucose measurement can also be informative, a device that you can pick up at most pharmacies.
To learn about the quantities of carbohydrate you’re consuming in foods and how they relate to you blood glucose, use the free Senza app food diary.
Even ‘so-called’ healthy foods like fruit can impact our blood glucose levels (proxy insulin and subsequent fat burning ability) in certain states. Therefore, timing carbohydrate ingestion so that it occurs during/after exercise may be most effective in terms of having the least negative impact on your fat oxidation rate.
Stress, in many forms, can raise blood glucose levels, and HRV monitoring can be an easy and practical means of understanding daily fluctuations.
If you, or someone you know has the signs of Type II diabetes, get in touch with experts at Virta Health.