One of the well-established findings in longevity research is that caloric restriction (CR) leads to increased longevity in every animal model, and there is significant evidence CR also improves human longevity.
In other words, in rough terms, consuming 30% fewer calories leads to something like a 30% increase in lifespan.
An interesting finding, but few of us would sign up for that kind of regimen, going a lifetime with reduced calories.
The good news, however, is that you don’t have to do CR for your whole life in order to get most of the benefits: periodic fasting does almost as well as chronic CR.
USC Professor Valter Longo, Ph.D. has gone one step further, developing what he calls a Fasting-Mimicking Diet (FMD) that he says gets the benefit of fasting while still having some food each day. He describes the connection between fasting and longevity in this TEDxTalk from 2016:
Dr. Longo is the author of The Longevity Diet, which describes a program of a basic daily diet along with an occasional 5-day FMD. I’ve listened to him be interviewed on various podcasts and have watched several videos, and I think he does a great job of explaining the science of how fasting reboots the immune system.
If the thought of fasting seems overwhelming to you, maybe you should consider FMD. At the very least, I hope you’ll watch the video above for a primer on why fasting or FMD can improve both lifespan and healthspan.
I personally haven’t tried FMD because I have found that fasting isn’t that difficult for me, and so I don’t feel a need to mimic fasting when I can do the real thing.
In future posts I’ll describe some fasting and time-restricted eating strategies that have worked well for me.
The scientific method involves proposing a hypothesis — e.g. “Drug A improves symptoms of Disease B” — and then designing an experiment, or study, to test it.
The “gold standard” studies are double blinded and placebo-controlled. Half of the subjects get the drug, and half get a placebo (or “sugar pill”) that has no expected effect. Neither the investigators nor the subjects know who is getting the real treatment. Then when the data are analyzed, it can be clear that any observed effect is the result of the drug, not wishful thinking.
And to reduce the likelihood that any observed difference is due to chance, scientists design their studies with a sufficiently large n, or number of subjects.
In an earlier post in this series, I conceded that I’m an n of 1. I’m an anecdote. Scientists tend to look down on anecdotal claims. Just because a low-carb diet and time-restricted feeding program has led to me losing 60 pounds doesn’t mean it will get the same results for you.
There could be something peculiar about me that led to this result. Perhaps it’s just a random coincidence. Or maybe just the fact that I had decided to pay attention and try to lose weight was the main factor, and the particulars of what I changed didn’t matter so much.
But together Lisa and I are an n of 2, and we’ve lost a total of 100 pounds on a low-carb diet with intermittent fasting or time-restricted feeding. And the weight loss for her didn’t really kick in until she went low-carb with intermittent fasting.
We’re also not alone. The n of those getting good results from a similar approach is much, much bigger.
And the reality is you can’t do a blinded study of a lifestyle intervention. If you’re switching from pizza and pasta to steak and eggs, you’re going to know it. And if you are going 12 hours a day or more without eating, you’ll know that too. There’s no placebo effect here.
I’m not sharing our stories to boast about our accomplishments. We did have to change what and when we ate, but it truly hasn’t felt like much of a sacrifice.
I’m sharing them because I’m frankly kind of mad that following official government policy (avoid fats, eat lots of “healthy whole grains”) made us fat.
The “eat less, move more” or “calories in, calories out” dogma is trite and simplistic, and doesn’t correspond with the reality of why we get fat.
In the 1950s and 60s nobody worked out. It was only in the early 70s that running and aerobics became “a thing.”
Obesity hasn’t tripled in the last few decades because people don’t move enough. If anything, people in recent decades have exercised much more than our parents and grandparents did.
Exercise is good and important, but its lack has not caused the obesity epidemic.
I’m sharing our stories because I’m pretty confident that among our social connections, and those we can reach through them, there are scores, or hundreds, or even thousands of people who feel as trapped and defeated as we did four years ago.
There is a better way, and there is hope for a reversal of metabolic syndrome. I want to point you to those from whom Lisa and I have learned this.
I look forward to sharing what we’ve learned from these people and others, and the benefits we’ve seen from applying those lessons. I linked mostly to their Twitter accounts in the list above, in case you want to start following them before I get to writing about them.
Some of them are physicians, while others are Ph.D. researchers, and still others are scientific writers actively poring through the relevant research. They have applied the skepticism of the scientific method to the disastrous dietary dogma that has had such a negative record for the last five decades.
So while Lisa and I together are only an n of 2 and our experience is not definitive, we have seen good results in the last four years through applying what we’ve learned from these people and others.
What other scientific researchers, physicians or writers have you found helpful in understanding diet, lifestyle, weight loss and health? I’d appreciate your recommendations as I continue my journey of exploration.
Dr. Jason Fung calls fasting “medical bariatrics.” For patients with type 2 diabetes it has the same benefits (under proper medical supervision) as bariatric surgery, but it’s totally reversible.
And compared to surgery or medications, it has radically fewer side effects. It’s been used by literally billions of people throughout history and has been part of every world religion.
And it’s even better than free. It actually saves money.
The other major positive aspect of fasting is its flip side.
Fasting isn’t a continual pledge of self-denial. It’s a decision to forego
eating for a time. And when the fast is over, it’s time for…
It’s not a great idea to break an extended fast (2-3 days or
more) with a huge meal. That can be a shock to your system. But if you
regularly maintain a narrow feeding window of perhaps 8 hours or less, and
occasionally throw in a 24-48 hour fast, it frees you to really enjoy
occasional excess without guilt or fear.
So as Dr. Fung says, “Enjoy that birthday cake!” Relish
those holiday meals.
For me, another big application is when I travel to our Mayo
Clinic locations in Phoenix and Jacksonville. I get to each of them perhaps
twice or thrice per year, and so I make sure to visit my favorite gluten-free
restaurants in each city.
I also eat at Zinburger, where in addition to gluten-free burgers and double-chocolate milkshakes they have a separate fryer where they prepare French fries loaded with cheese and bacon.
Thankfully, when I visit I’m usually there a couple of nights, so I can make it to both places.
As I write this, I’m in the Sky Club in Atlanta on the way home from a couple of days in Jacksonville. That meant on Thursday night I got to visit V Pizza in Jacksonville Beach, where I had the Carnivora with gluten-free crust:
The great part about fasting is that I can look forward to meals like this because I know I will have them a few times a year at most. So I couldn’t develop a habit of visiting these restaurants more frequently even if I got a sudden craving.
When I do eat there, I typically have fasted since dinner the night before, and will fast the next morning as well.
So even though I’m eating 10-15 times the carbs I usually have, within a day or two of my feast I’ll have burned the sugar and starch and be back to gluconeogenesis and maybe even moving toward ketosis.
If you haven’t tried fasting, I’d encourage you to investigate its benefits. Read about our 10-week alternate daily fasting experience. And again, if you’re on diabetes medications or insulin you absolutely do need medical supervision to prevent hypoglycemia.
Once you’ve developed a time-restricted feeding or intermittent fasting pattern or mindset (especially a low-carb diet), you’ll not only be free from the tyranny of cravings and having food seem so important.
You’ll also really enjoy the times when you do feast.
If you want to explore why intermittent fasting works, this video featuring Dr. Fung is a great way to start.
As I mentioned in this post, when I heard Art De Vany say he eats “two meals a day, sometimes one, sometimes none” I thought that was unfathomable.
But after reading The Obesity Code and The Complete Guide to Fasting, in which Dr. Jason Fung described his experience with his Intensive Dietary Management clinic and how he would get many patients with type 2 diabetes off insulin and diabetes medications within just a few weeks through extended fasting, Lisa and I were ready to give it a try.
Neither of us had even been diagnosed as prediabetic, but Lisa’s fasting blood sugar had been 102 in October 2016, which is what got us started on this dietary and lifestyle journey.
In The Obesity Code, Dr. Fung cited a study of 70 days of alternate daily fasting in which body weight was decreased by an average of 6%, while fat mass decreased by 11.4%, with no loss of lean mass. He also said
Studies of eating a single meal per day found significantly more fat loss, compared to eating three meals per day, despite the same caloric intake. Significantly, no evidence of muscle loss was found.
The Obesity Code, p. 243, Jason Fung, M.D.
It’s important to note that with alternate daily fasting, you’re still eating every day. Typically you eat dinner every evening, and skip breakfast and lunch every other day.
So on Sunday you would eat all three meals, but then on Monday skip breakfast and lunch, limiting yourself to water, black coffee or tea. Then repeat the cycle.
Two Three important additional points:
If you are taking insulin or medications for diabetes, you absolutely need to have medical supervision while fasting to prevent dangerous low blood sugar episodes.
If you’re eating lots of carbohydrates, you will be miserable on an all-day fast. It’s best to get at least somewhat converted to fat metabolism before starting fasting. Eggs, meat, avocados, nuts and other foods relatively high in fats and with moderate protein, combined with limiting carbs to 25-40g per day, will help convert your body to burning fat.
I’m not a doctor. I’m not giving medical advice. Check this out for yourself and make your own decision in consultation with medical professionals you trust.
One more tip: a good way to start is with time-restricted feeding, just skipping breakfast every day and eating lunch and dinner during a 6-8 hour window. This still gives you an extended period of lowered insulin levels, and isn’t quite as extreme as going 24 hours without food.
With all of those caveats, here are my weekly bluetooth scale readings from our 10 weeks of alternate daily fasting. I weighed every day, but for simplicity am just sharing the Wednesday morning readings.
With the caveat that the body fat and muscle percentages seem to be calculated by some voodoo electrical signals running through the soles of my feet, at least all of those readings were coming from the same scale.
So the bottom line is that I lost about a pound of fat per week while essentially preserving muscle mass. (The other 4 lbs. lost, according to the scale, were water weight .)
Note also that when we started the 10-week experiment I was already down 37 lbs. from Peak Lee, as demonstrated in my “before” pictures. So presumably I had already lost the “easy” weight.
And in keeping with the study cited by Dr. Fung, my body weight was reduced by 6.2%, while my body fat was reduced by 18.1%, during the 10-week period.
Have you tried intermittent fasting or time-restricted feeding?
The Obesity Code by Dr. Jason Fung came up among my recommended titles on Audible in May of 2018.
The name didn’t put me off, because the subtitle was compelling: “Unlocking the secrets of weight loss.”
And while by that time I had lost about 25 lbs. through the Trim Healthy Mama Plan and the Slow-Carb Diet, I figured this highly rated and recommended book would add to my knowledge.
Little did I know it would be among the most important books in my health journey.
Dr. Jason Fung is a nephrologist who became increasingly dissatisfied with his practice because he felt helpless to deal with the progressive kidney damage his patients were experiencing.
Many if not most of them had diabetes resulting from obesity, which led them to need increasing amounts of insulin, which led them to gain more weight, and the cycle would continue. Eventually, they would end up on dialysis or would have foot ulcers that required amputation.
In listening to this book, I felt an increasing sense of the despair he must have felt in his practice, because in the first several chapters he laid out the scope of the problem, describing both the epidemic of obesity and why so many diets fail.
Essentially our weight control mechanisms behave like a ratchet, at least in our current food environment. Once we gain weight and our bodies adapt to a new normal, they in effect establish a new “set point.”
If we then follow the “eat less, move more” advice as exemplified by The Biggest Loser, we may achieve some short-term success, but at a long-term price. With chronic caloric reduction, our metabolisms slow because our bodies sense starvation and the need to conserve energy.
Instead of a basal metabolic rate of, for example, 2,000 calories per day it may be reduced to 1,500.
Our body temperature is reduced, as is the stroke volume of our hearts. We end up cold, tired and hungry.
Then when we resume normal eating, we gain it all back (and more) because we still have the lowered metabolism.
Fung describes obesity as primarily a hormonal issue, and highlights those hormones that play the largest roles: leptin, grellin, cortisol and, above all, insulin.
He describes how the Atkins diet showed some success, but that it too tends to have problems with long-term compliance.
This dreary story continues for 18 chapters, until he summarizes as follows:
There are two primary findings from all of the dietary studies done over the years. First: All diets work. Second: All diets fail.
Dr. Fung then gives some helpful advice on the importance of eating whole foods and avoiding sugar and refined carbohydrates. But it isn’t until the final chapter, after nine hours of describing the futility of other approaches, that he provides the solution.
As I said, the title of this book is really unfortunate. I would love to have all of my friends read it, but the title makes it kind of awkward to recommend.