For those of you who follow me on social media platforms like Instagram and Facebook, you saw me posting about the Low Carb U.S.A. conference that I recently attended. It is a great way to stay on top of the research about living a low carb lifestyle, in addition to getting a chance to hear from and meet the internationally-renowned leading minds in the field! The line-up included people like Dr. Nasha Winters (one of my favorite authors on living a fully-holistic ketogenic lifestyle – find her life-changing book here), Maria Emmerich, Dr. Andreas Eenfeldt (a.k.a. The Diet Doctor), Gary Taubes, Nina Teicholz (author of the incredible The Big Fat Surprise, which should be required reading for anyone wanting to live low carb!), Dr. Gary Fettke, and Dr. Stephen Phinney TO ONLY NAME A FEW! So, needless to say, it was quite the line-up and I was honored to be in the same room with these amazing minds!
Because I’m a nerd (Don’t believe me? Here’s my book list!) and also because living low carb has radically changed my health and the course of my life (find my story here), I make it a point to stay well-informed of the science and updated research on the topic. However, there was one lecture in particular by Dr. Stephen Phinney, a trailblazer for a low-carb lifestyle that has been doing research on the success of living low carb for decades – even for endurance athletes and even before it was “trendy,” that COMPLETELY rocked my world! It was about fasting and it completely changed my mind about fasting!
I describe in a previous blog that the longest I have fasted to date was 72.3 hours. My fasting schedule is not about starvation. It’s about retraining my body, previously crippled by severe reactive hypoglycemia, to be able to build strength running off it’s own fuel so that my blood sugar doesn’t crash as it used to, creating a horrible quality of life for me that went beyond just being “hangry”. And, while I happened to do that extended fast for spiritual purposes (as is a practice that has been done for thousands of years across many different religions), based on Dr. Phinney’s lecture, I will NEVER do this again. Here’s why:
The News to Me!
While I had always read about the power of extended fasting to harness the power of cellular healing processes like “apoptosis” and “autophagy” from various other leaders in the field, the understanding was that such fasting was always healing. Heck, the longest recorded fast was 382 days long! Proponents of extended fasting, like Dr. Nasha Winters’ work with patients with terminal cancer or Dr. Jason Fung’s work with the/Diabetic obese, describe that muscle loss is not an issue. However, Dr. Stephen Phinney explained that we “self-compost” protein/amino acids. So, we excrete nitrogen (which is around 6 grams of protein for every 1 gram of nitrogen) every day. The challenge? If you’re not eating, you can’t replenish that lost nitrogen. So, yes, your metabolism increases, but it’s as a result of a stress response used for survival that includes things like cortisol and adrenaline.
What This Means
Given that half of the protein in the body is muscle, this means that fasting weight loss can be around one pound a day. But, half of this weight comes from lean body mass! So, Dr. Phinney went on to explain that we simply don’t have enough information how fasting more than 24-36 hours affects the body to be able to say that it is “safe” and has “no long-term negative effects.” Extended fasts aren’t likely to kill you but the challenge is that, without more research, we simply don’t know if the alterations in the metabolism and any potential damage caused by extended fasts have cumulative effects over weeks, months, or years.
Don’t Rule All Fasting Out Yet, Though!
There are a couple protective factors that Dr. Phinney did describe, however. They are as follows:
- The obese, who have a lot more body fat that they can use as clean fuel (e.g. ketones), don’t have a much of a risk of this given that they have their fat stores to burn through.
- Intermittent fasting for up to 24 hours, given that it is been the way that we have survived as a species when food is both plentiful and scarce (Dr. Fung has some great books on this topic: The Obesity Code and The Complete Guide to Fasting), is not inherently risky. This is because it is the period of fasting past 24-36 hours that we simply do not know enough about related to the way it affects metabolism.
- If extended fasting is done in a way where protein can be spared (technically called “Protein-sparing modified fasts;” something like a diet of less than 800 calories a day but with high levels of protein), Dr. Phinney’s research has shown that lean body mass can be maintained even related to muscle mass for endurance athletes!
Interestingly, although Dr. Phinney was the one who bravely warned of the potential dangers of fasting, when other leading physicians/researchers in the field were asked questions about extended fasting, the consensus was that none of them (other than someone like Dr. Nasha Winters, who works with terminally ill cancer patients and is focused on short-term rapid healing and survival) would recommend fasting for any more than 24 hours. Wow! News flash to me!
So, needless to say, my mind has been TOTALLY changed on fasting!
Hopefully, as Dr. Phinney commented, we will learn to know more about extended fasting. Hopefully we will find that, given the amazingness that is our body and the ability for us to survive this long as a species, extended fasts don’t, in fact, cause irreversible damage to our metabolism. In the meantime, however, you will see me fasting for no more than 24 hours. I’ll take any chance I can get to enjoy some more tasty low-carb recipes, anyway! 😉
Reference:
Phinney, Stephen. 2019. Metabolic Effects of Fasting: A Two-Edged Sword. [Powerpoint slides]. Retrieved from Low Carb U.S.A. San Diego 2019 Conference.
