There is increasing evidence from recent human and animal studies that intermittent fasting — refraining from food or caloric beverages for at least 12 hours a day, several days a week — reduces the risks of cardiovascular disease, dementia and cancer. Those benefits are well-documented in the hyperlinked articles, so I won’t repeat them here. Yet many nutritionists hold that skipping breakfast or other meals and snacks can lead to weight gain and metabolic imbalance. Several recent articles have suggested that IF and breakfast skipping is a particularly bad idea for women. Much to my chagrin, this view been even embraced recently by a number of ‘Paleo’ advocates whom I respect, such as Chris Kresser and Mark Sisson.
In this post I’d like to address three main objections that have been raised against skipping breakfast and other forms of intermittent fasting:
- It spurs hunger cravings, leading to compensatory overeating and obesity
- It causes cardiovascular disease and metabolic dysregulation of blood glucose and hormone levels
- It’s bad for women, leading to hormone imbalance, disrupted menstrual cycle, and heightened stress response
I believe these concerns with breakfast skipping are overblown, based on an incorrect interpretation of a few animal and human studies, and flawed personal implementation. To the contrary, adaptation to meal skipping can actually help boost stress tolerance and improve blood sugar control. If practiced correctly, intermittent fasting (IF) can actually be a powerful tool to overcome hypoglycemic symptoms, and regain control over a harried lifestyle. And it can be particularly useful for women who are struggling with cravings, weight management and stress management.
Opposition to intermittent fasting arises from both published research and anecdotal reports. I’d like to address both in this post. I’ll first point out some significant flaws in the interpretation of several recent studies purporting to show negative effects of reduced meal frequency on women and other groups. And I’ll end by pointing out how to avoid common mistakes made by many who try intermittent fasting find it to be unpleasant and unsustainable.
Approached correctly, IF can provide major health benefits for most us.
My recent post on Why I don’t take vitamin D supplements generated a lot of interest and a few misconceptions. In that article, I did not suggest any practical alternatives to taking high dose vitamin D supplements. Here I will suggest a way that may provide the benefits of vitamin D without popping any pills, spending all day in the sun, or ingesting copious amounts of fish.
Some readers got the idea that I believe vitamin D is not beneficial, and that I discount the evidence from studies that show the benefits. I want to dispel that notion. I do acknowledge the key role that vitamin D and the vitamin D receptor (VDR) play in bone mineralization and regulation of innate and adaptive immunity, and among other things. I further acknowledge that many (but certainly not all) studies support an association between higher vitamin D3 levels and reduced incidence of diseases such as cancer.
As I wrote:
Nobody doubts the important role of vitamin D in the body. But are higher levels of a hormone like vitamin D–whether or not provided as a supplement– always a good thing?
My doubts are focused on several points:
My article created a dilemma for several commenters. These people acknowledged the risks, but nevertheless cited benefits they personally experienced from supplementing with vitamin D–ranging from fewer colds and flu, to relief of autoimmune symptoms, and even lessening of depression.
For these people, a key question remains:
Is there a way to get the benefits of vitamin D supplementation, while avoiding the dependency and risks of taking vitamin D capsules daily for the rest of your life? While I don’t have a definitive proven answer to that question, recent research leads me to speculate here that there is a promising approach that is within everyone’s reach.
It lies within a powerful natural biological process called autophagy.
What a great conference! I had heard such high praise for the inaugural meeting of the Ancestral Health Symposium last August, but I was too late to register in 2011. This year I submitted an abstract that was accepted as a poster presentation. For those who missed it, I’ve attached a copy of my presentation below.
What an edifying and uplifting experience! We just wrapped up three days of excellent talks, panels, poster presentations and plenty of informal networking and socializing. This conference is really the hub of the Paleo movement. The emphasis was on the most recent developments in the scientific, cultural, political, and practical approaches to overcoming the contemporary health epidemics that derive from a mismatch between contemporary lifestyles and the biology of our evolutionary heritage. The talks and panels were diverse, covering nutrition, cholesterol, cancer, immune health, farming, exercise, and many other topics.
One of the primary topics covered on this blog is intermittent fasting (IF). Many approach IF as a diet or weight loss method. I know from research, personal experience and conversations with others that IF can indeed be an effective way to drop unwanted pounds. However, viewing IF as merely a new way to diet entirely misses what I believe is the most important reason to pursue it: the activation of hormetic processes that foster improved health, keep degenerative diseases at bay, and hold out the promise of a longer, more vibrant life. These benefits are a known consequence of calorie restriction, but intermittent fasting offers a more comfortable and versatile way to reap the benefits of calorie restriction without the sense of deprivation, the loss of lean body mass, and the metabolic risks that have been associated with simple calorie restriction.
It is because I’ve found intermittent fasting to be an attractive practice, both scientifically and personally, that I was so excited to be invited to give a lecture on IF at The 3rd Door, an innovative health and fitness studio, cafe and social center in downtown Palo Alto. The fitness director at The Third Door, Johnny Nguyen, is himself an advocate and practitoner of IF, which he blogs about with great flair and common sense at The Lean Saloon. The talk gave me an opportunity to reframe intermittent fasting in the terms of the philosophy of Hormetism, or applied hormesis that I write about on this blog. I believe that the framework of hormesis helps to make sense of why IF works, and why it is so much more than a diet.
What follows is a video of my talk on the benefits of intermittent fasting, presented on May 18, 2011 at The 3rd Door. I would like to thank Dianne Giancarlo and Johnny Nguyen for inviting me to speak, Vaciliki Papademetriou for technical assistance, Francesca Freedman for introducing me to The Third Door, Tom Merson for the still photos and Ken Becker for the masterful video production.
Posted 23 May 2010 — by Todd
One of the first scientifically rigorous demonstrations of the benefits of hormesis was a 1934 study of calorie restriction (often abbreviated “CR”) in laboratory rats, conducted by Mary Crowell and Clive McCay at Cornell. They found that reducing the calories of rats by 30-50%, supplemented with adequate micro-nutrients, could almost double their lifespans. Later studies found continued lifetime extension with calorie restriction up to 65%. In addition, the rats remained energetic and youthful in appearance, with greatly reduced incidence, and delayed onset, of age-related diseases. This same phenomenon has been observed in a variety of other animals.
Studies on calorie restriction in primates or humans are as yet inconclusive. Controlled primate studies only started in the late 1980s and have yet to be completed, although the preliminary indications are very promising. And in humans it is more difficult to conduct controlled studies for both ethical and compliance reasons. An additional factor to consider is that animals raised post-weaning on calorie restricted diets typically have much smaller adult body sizes that animals not restricted in their eating. Because of the social and physical implications of this consequence, advocates of calorie restricted diets for humans advise that they be started only upon reaching adulthood.
Whether or not a restricted calorie diet extends the human lifespan, the evidence is becoming overwhelming that a nutritionally complete diet with reduced calories has the potential to greatly improve our health, particularly as we age. But is it practical and possible for humans to happily adhere to such a diet?