I get regular questions about fasting, from people trying to lose weight, cleanse their bodies, or just learn more about ‘alternative’ practices. It’s sometimes a tough question, as fasting is a practice associated with both life-changing healing experiences as well as horror stories, and so there are some strong opinions out there. Additionally, fasting has a long association with religious practices – monks, shamans and lay people the world over have fasted for spiritual reasons since recorded history began. Finally, it’s Ramadan, the Muslim month of fasting, so this week, I’ve opted to give my thoughts on fasting.
Let me start by saying that there is not a lot of research on fasting in humans – the little I have been able to turn up focuses on the performance of athletes observing Ramadan, and a few lab studies on how fasting affects gene expression. There is evidence that caloric restriction does increase lifespan among a wide variety of animals, but there are questions as to whether this would apply to humans as well. The most interesting research I came across was a group of studies that indicate that fasting induces production of a group of proteins called sirtuins, which have been characterized as ‘anti-aging’ proteins, and have the effect of increasing alertness and energy efficiency. From an evolutionary perspective, it appears that these proteins were induced during periods of famine, increasing our ancestors’ likelihood of finding food and surviving to pass their genes on. They have recently become major targets for commercial ‘anti-aging’ products.
So in the absence of a large body of research, here are some basic ideas on fasting, based on clinical experience and sound judgment.
First of all, let me say that I am not in favor of drastic fasting, like multi-day water fasts, multi-day juice fasts, or the perennially popular Master Cleanse. I don’t see benefit in depriving oneself of all calories for substantial periods of time, and I especially don’t see benefit in consuming sugary drinks at the expense of nutrients. It’s my belief that juices and the Master Cleanse, because they lack the mollifying effect of fiber and protein, subject your body to the stress of a blood sugar roller coaster, without much benefit. One of the benefits of fasting is giving the body a bit of a ‘metabolic break’, and drinking juice causes unhealthy spikes and valleys in blood sugar levels.
That said, I do believe that fasting can be healthy. Here are some essential components of healthy fasting: avoidance of unhealthy foods, mild caloric restriction to induce sirtuin proteins, reduced activity levels so as not to stress the body, short duration to prevent negative outcomes, and easily digestible foods consumed to break the fast.
Before I cite specific fasting practices, let me say that I think our bodies are more complex than we understand, and that practices that have a long cultural history are worthy of our attention. Our scientific minds have limited understanding, and can sometimes lead us astray – low-carb dieting is a good example – and I believe that long-standing cultural practices have survived because they work. This is why I recommend the Mediterranean diet over low fat diets.
I find two main healthy examples of intermittent fasting, or periods of lean eating, in our cultural history. The traditions of both Lent and Ramadan are associated with forms of fasting, which I believe may have more beneficial health effects than our modern aggressive forms.
Fasting during Lent has taken many forms in the past, including daytime fasting with evening breakfasts and abstinence from animal products. Certainly, the abstinence from animal products for substantial periods of time has beneficial health effects, as it provides a respite from significant sources of saturated fat and cholesterol in the diet. In our modern time, Lent has been associated with abstinence from meat on Fridays, a theme that I believe can be converted into a plan for weekly fasting – caloric restriction once a week for a set period of time satisfies the criteria I mentioned previously for a healthy fast, and I think that we may do well to embrace this form of fasting.
Daytime fasting, followed by breaking of fasts with balanced, easily digestible meals is also worthy of our attention. I’d posit that this method of fasting is effective at inducing sirtuin proteins while also providing adequate nutrition. While this method of fasting is practiced daily for long periods of time in Ramadan, and was practiced for long periods of time in older Lenten traditions, I don’t think that it needs to be practiced for long periods to be effective. Fasting once a week on occasion may be similarly effective. Most important, I think is that the meal that breaks the fast be easily digestible and provide a balance of protein, fat, and carbohydrates, along with a range of vitamins and minerals.
Several years ago, I learned of the Moroccan practice of eating harira to break the Ramadan fast, and was really inspired. Harira is a soup consisting of lentils, chickpeas, tomatoes, onions, rice, olive oil, a small amount of meat or broth, and a rich array of herbs and spices. This meal provides a good balance of protein, carbohydrates and unsaturated fat, and is rendered extremely easily digestible by a combination of long-cooking and the use of spices that aid digestion and assimilation, such as ginger, pepper and coriander. When it comes to easily digestible foods after a period of fasting, I think harira may have it nailed.
And finally, one important oversight that I see people make consistently is that they don’t give themselves a break while fasting, and just keep at their normal activities. Sometimes this is difficult to avoid, but I think it’s important to give our bodies a break while we are depriving them of calories – maintaining a high level of activities on a low amount of calories stresses the body physiologically, which I think is less than healthy.
My final message today is a restatement of the important components of a fast: avoid unhealthy food, mildly restrict calories, take it easy, keep it short, and eat gently to break the fast. Above all, keep it sane – crashing your system is the opposite of what a fast should achieve.