In Dr. Volek and Phinney's books The Art and Science of Low Carbohydrate Living and The Art and Science of Low Carbohydrate Performance they define HFLC in ketogenic terms. They find that typically speaking this requires a restriction in carbohydrates to 50 grams or less per day (ketosis is defined by your body's ability to produce 0.5mmol/liter or greater of ketone bodies). This likely holds true for the vast majority of people; certainly if they are non active. By this definition, I am not in line with HFLC protocol. I do drop my carbohydrate consumption down to these levels when in recovery as a way to reduce inflammation and recover faster. But when I'm in peak training, I rarely fall as low as 50 grams a day; certainly not on average.
Although my goal is not to remain in ketosis, I likely still find myself there often enough, despite surpassing the 50 gram marker. This is due to my extremely active lifestyle and, in my opinion, use of Vespa Power products. These allow me to "get away with" more carbohydrates than a sedentary person. If the carbohydrates I eat are timed strategically, I am likely in a state of ketosis quite regularly (my ketone body levels during the FASTER study ranged from .4 to .7 mmol/liter).
If you are interested in seeing a well-written description of the data emerging from Dr. Volek and Dr. Phinney's FASTER Study, check out this recent article from Ultrarunning magazine: Emerging Science on Fat Adaptation.
So why does this matter? It matters because there really isn't, and shouldn't be, a single definition of HFLC that can be applied to everyone. Just like there is no "cookie cutter" training plan that works for everyone, there is no specific number of grams/day of carbohydrate that fits everybody's genetics and lifestyle. There are people who can likely ramp carbohydrate consumption to 4-5 times that of what would be possible for others and still remain in a state of ketosis.
The last thought to consider is: Should ketosis be my goal? For me, and for the athletes I coach that follow an approach called Optimized Fat Metabolism (OFM), it is not the goal. The goal is to improve performance. This means using nutritional ketosis as a tool or core principle, but not as an end all, be all. My goal, and the goal of anyone following OFM, is to become as fat adapted as possible without sacrificing the high octane performance benefits of refined carbohydrates. I never have, and never will, argue that carbohydrates aren't a great source of fuel. The misconception comes in how many and how often we need them. I treat carbohydrates like a stimulant: When used properly they can vault you to the next level. When abused, they can leave you wrecked, burnt out, puking up gels, or in the worst of scenarios finishing an event in a state akin to going into shock.
So, am I HFLC? I believe so. After all, the majority of my calories always come from fat, my carbohydrate calories rarely surpass protein calories, and my maximum rate of fat metabolism peaked at 1.57 grams/minute (previous studies have shown .9-1.0 g/min. as maximum potential). But in the end, a label, properly defined or not, isn't going to get me to any finish lines any faster.
Nice post. I've never seen anything that would lead me to believe being in ketosis all the time is necessary for anything (assuming you're healthy, and not suffering from one of the conditions that specifically require it).
ReplyDeleteI've also not seen anything that indicates that if you are in ketosis all the time, it's harmful.
And people seem not to realize that there are two ways to go into ketosis: one is to eat low-carb, the other is exercise.
What seems to be optimum is being in ketosis regularly. The worse thing to do for yourself is to never go into ketosis: eating too much carbs all the time and not exercising.
The other thing to remember is that we're at the beginning of understanding how this works, as demonstrated that the fat-burning capacity of a human has been under-estimated for decades!
Keep up the good work!
Thanks Zach, good article. It's important to understand that, even while in ketosis, fat - not ketones - are the main source of fuel during exercise. I think that's where many people misunderstand LCHF & the ketogenic diet and its relation to exercise and fueling. As you say, nutritional ketosis can be a good baseline to work from but should be seen as a tool and a means to an end, not the end itself.
ReplyDeleteHallelujah! It's great to hear what I keep telling people about low-carb from someone who's actually doing it and getting results (and it's the results that do matter).
ReplyDeleteGreat post Zach! As you say everyone is an N=1 and the variation among humans is pretty wide but for each person that N=1 is their science. Now on the other end of the spectrum some athletes need to go down to under 30 gms /day to induce the physiological shift to being fat-adapted. Stephanie Holbrook represents a lot of people, particularly women athletes who struggle with inducing ketosis enough to trigger the shift. Those who are struggling may gain valuable insights from this podcast: http://fitnessnerds.podbean.com//e/coachsteph/
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