Fasting: When your body begins to eat itself
And why that's good for you
What if there was a medicine that everyone could take to improve their metabolic health - regardless of age, diet, wealth, or lifestyle? Hello, intermittent fasting.
While it may seem like a relatively new fad, fasting is as old as our ancestors who gorged on food when they found it, but sometimes went days without eating. Periodic fasting is recommended by almost every major culture out there, albeit usually with a spiritual focus.
Today’s sedentary lifestyle is exacerbated by our hedonistic eating habits that don’t give our body time to recover. Think about it - we are awake 16 hours a day on average, and most of us eat something every 2-3 hours - be it a meal or a snack. While snacking was encouraged beginning in the late 70’s, it has largely just benefitted large companies that have churned out more and more processed food. The former wisdom, and what a growing number of people are coming around to today, is to eat 2-3 filling meals a day with lots of healthy fat, protein and fiber that will power you for 4-6 hours between meals.
So why is fasting beneficial?
Arguably, the biggest benefit of fasting is that it reduces insulin resistance which is deeply linked to chronic diseases like type 2 diabetes and cardiovascular disease. Fasting lowers your insulin levels, because you don’t need as much insulin when you’re not eating. And when your insulin levels drop, weight loss often follows. And what’s more, weight loss that occurs as a result of fasting usually targets belly fat or subcutaneous fat which is the most harmful kind of fat on your body, and can predispose you to chronic disease.
In addition, fasting activates autophagy - which is a process that kicks off a series of biological changes that rejuvenate your cells. Weaker mitochondria die and new, stronger ones take their place - think of it as a spring-cleaning for your body! It literally slows down the process of aging.
Why does it work?
Our body has two ways to create energy - glucose that comes from the food we eat (primarily carbs), and energy that it creates from your stored fat. Once it uses up the glucose, it moves on to our fat reserves. This is called metabolic flexibility. But if we keep replenishing the glucose by eating often, we don’t give the body a chance to tap into its fat reserves.
Body weight is tightly regulated by a symphony of hormones - in particular insulin, which is a fat storage hormone. If you’ve got high insulin levels, you cannot burn fat. Dr. Jason Fung, a nephrologist and the author of The Obesity Code, talks about the concept of homeostasis - body weight balance, which is regulated by hormones. Think of it like a thermostat, which has a set point. When you increase the number of calories you eat, your body starts to burn more so that it can keep your body at its set weight. Conversely, if you start to eat less, your body will reduce the amount of energy it burns, to keep you at your set weight. This is why calorie counting often fails to work after initial effects.
Two highly effective ways to reduce your insulin levels are following a lower-carb diet and fasting. When you eat is just as important as what you eat.
A few years ago I could not comprehend the concept of skipping a meal. I woke up ‘starving’, or at least I thought I did. But I always felt sluggish after breakfast. I decided to try fasting 12 hours (8pm-8am), with trepidation. As I neared the 12 hour mark, I wondered how I would feel. And then, big whoop, I felt nothing! I didn’t even know how much time had passed because I was on a call.
While it’s possible to do longer fasts, I found that I’m happier when I do 12-14 hours, and research has shown that this is very safe. Now I find it hard to eat before that, and usually regret it if I do as I am not hungry. My energy levels are usually higher when I’m fasting and I often work out in a fasted state. My mind is razor-sharp and focused, no more post-breakfast slump. And honestly (even though I love to cook) I spend less time meal-planning, cooking and cleaning which is honestly quite liberating!
It can be daunting to start, so go slow and just postpone a meal for 15-20 minutes at a time to see how you feel. While fasting within your circadian rhythm (start eating earlier in the day, stop eating earlier in the day) has been found to be very effective, it is usually easier to skip or postpone breakfast than dinner, as dinner often has social implications with family or friends.
But most of us cannot do without our morning cuppa, and a common question is how to take your morning coffee or tea if fasting. Ideally, you would take it black - I do and love it. But there are modified versions where you can add a splash of cream or whole milk or unsweetened almond milk to your beverage - a tiny amount of calories should still give you most of the same benefits. Skim milk, creamers or sugar (even artificial sweeteners) are usually the ones to avoid, as they can spike your insulin.
I also often sip on black coffee, green tea or herbal teas when fasting. Caffeine has been found to be mildly beneficial as it can increase your metabolic rate.
Drink lots of water. Sometimes when you think you’re hungry you’re really just thirsty! I like (unsweetened) sparkling water as well. Chewing sugar-free gum occasionally also works.
But I find it is best to keep busy - fasting is easiest when you’re busy at work or home rather than on holiday when you keep thinking about your next meal.
Breaking your fast
Breakfast is so named because it literally breaks your night of fasting. It is also the best time to ensure you eat a balanced meal so that your insulin doesn’t stay consistently high for the rest of the day. Unfortunately, typical breakfast foods are typically high-starch and high-sugar - think cereal, instant oatmeal, croissants, bagels, orange juice and the like. To moderate your insulin levels, emphasize fat, protein and fiber at breakfast. If you like to eat fruit in the morning, do that after your protein-rich meal.
An important caveat is for those who are taking insulin - not to attempt longer fasting periods without being overseen by a doctor as this can be dangerous. It is also worthwhile to note that most research has been conducted on young white males, so the effects on women are not well-understood - it’s possible that very long windows of fasting can have downsides, particularly on menstruating women. Many women have been found to do better with shorter windows of 12-14 hours.
If you do extended fasts (24-36 hours or longer), be sure to replenish electrolytes (salt, magnesium, potassium) that your body loses. In addition, break an extended fast gradually - don’t eat a huge meal. Start with some vegetable broth, then eat a small-ish meal emphasizing protein, fat and fiber. This will give your body time to adjust.
It takes a lot of drugs to achieve the same benefits you can get for free with fasting. Combined with a whole-foods diet, it has been found to reverse metabolic dysfunction and inflammatory chronic diseases in many. There is even clinical research being conducted on if it can help treat cancer. While different diets (low-carb, low-fat, paleo, vegan, etc.) can be polarizing, fasting is unique in that anyone can do it and experience benefits. But it’s important to go slow, and see what works for your body and is sustainable for you.
Fung, Jason. The Obesity Code: Unlocking the Secrets of Weight Loss (Why Intermittent Fasting Is the Key to Controlling Your Weight). Vancouver/Berkeley: Greystone Books. See also his YouTube channel.
Dhru Purohit Podcast: How to Use Intermittent Fasting to Lose Weight, Live Longer, and Feel Better with Dr. Jason Fung
The Ultimate Health Podcast: The Complete Guide to Intermittent Fasting for Women with Cynthia Thurlow
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