For the past few months I’ve written extensively about the benefits of intermittent fasting, something I’ve been practicing in my personal life for the past two years. I also work closely with a number of people who are currently fasting intermittently.
Intermittent fasting is an eating pattern in which you don’t eat any calories for an extended period of time. Usually between 12 and 40 hours. The results can be remarkable for those who follow the rules closely. This means fully understanding that fasting consumes nothing but water, black coffee, or unsweetened tea. The key is to avoid anything that triggers an insulin response because insulin helps you store fat.
I was meeting up with a good friend who had just returned from vacationing at a resort in Mexico. In the last few months of intermittent fasting, he’s lost 27 pounds of body fat, and it’s particularly evident in his greatly reduced waistline. He told me how in the past at the resort he wasn’t able to walk the mountainous trails nearby but this time he flew along and loved it. Additionally, he confided again that the intermittent fasting approach is the easiest and most effective thing he’s ever done to manage his weight.
So here’s what you need to know about intermittent fasting and how it could benefit you:
How does intermittent fasting affect the body?
Like many others, I was drawn to intermittent fasting not only for the weight management benefits, but also for several other health benefits. It makes sense to me that by relentlessly eating food at regular intervals—breakfast, lunch, dinner, and late-night snacks—I’m giving my body the message that digesting food is a priority. Since digestion, especially of dietary fat, takes several hours, the body is actively involved in the digestive process from early breakfast to evening snacks and many hours beyond.
As a result, the body gets minimal breathing space from digestion and only fasts for a few hours, at best late in the sleep cycle, which is short-lived as breakfast is soon to come.
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This is an important consideration because the gut contributes to health in many ways, especially when it comes to the immune system boosts that occur during fasting. Hand-in-hand with increased production of immune cells goes autophagy, the body’s method of cleaning out damaged cells to regenerate newer, healthier cells. A good analogy for autophagy is taking out the trash or cleaning up the debris. The debris in this case consists of parts of body cells that are damaged and must be removed so that new cells can develop.
Fasting also promotes the production of human growth hormone, which helps you shed body fat and maintain muscle, both of which become more important to health as you age.
How do I do intermittent fasting?
There are several ways to approach intermittent fasting. My approach is to fast daily and only eat food in a narrow window of two to four hours. I gradually built this up, starting with a larger window and gradually reducing it. Around the 18 hour mark of the fast, the benefits described above kick in and accelerate.
Here’s what I outlined in a previous column about my typical daily approach to intermittent fasting: I imagine what I would normally have eaten for breakfast and lunch, plus snacks (power bars, nuts, etc.) and consume those “after.” my first meal of the day at 6 p.m. I drink black coffee regularly throughout the day, which keeps me comfortably full until dinner.
And let me add, if I want to cheat at night with a treat like a hot fudge sundae, I don’t hesitate.
Also, my workouts are great with no loss of energy despite fasting many hours before the workout.
How is intermittent fasting different from other crash diets?
A reader recently wrote to me about intermittent fasting. He wrote: “I’ve read your books on nutrition, healthy eating and exercise, and you rail against crash dieting because lack of nutrients leads to loss of muscle mass. Now, I’ve read about your use of intermittent fasting, which reduces calorie intake to zero for extended periods of time, and I’m wondering how this differs from calorie restriction on a crash diet?
An insightful question worth investigating.
First, on a crash diet, you reduce your calorie intake from perhaps 2,000 calories a day to less than half that amount and enter semi-starvation mode. When you drastically reduce calorie intake, the body struggles to keep your blood sugar, known as glucose, at optimal levels. Blood sugar is crucial because the brain depends on glucose as its primary source of energy, and of course the brain is the body’s top priority.
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Glucose is stored in the liver as glycogen. When you eat “normally,” when blood sugar levels drop, glucose is released from the liver to raise the levels again. However, on a crash diet, the supply of liver glycogen is depleted as the body is in semi-starvation mode. So when blood sugar levels drop, the body is alarmed that the liver cannot respond appropriately.
This, in turn, prompts the body to take emergency measures. The hormone cortisol is released, which breaks down muscles into proteins, which are further broken down into amino acids. Selected amino acids are transported to the liver and converted into glucose, which strengthens blood sugar levels. In other words, the body breaks down muscles to make glucose, and the process is called gluconeogenesis.
Are there any advantages of crash dieting over intermittent fasting?
Crash diets always fail because losing muscle mass is counterproductive, and even if you lose a lot of pounds, the fact that you’re losing several pounds of muscle doesn’t mean you look any better. That’s disappointing, because when you start a crash diet with the goal of losing 30 pounds or more, you picture in your mind’s eye going back to the body that was 30 pounds less fat. Your “new” crash diet body doesn’t look like you imagined it.
Also, you tend to feel lousy and only think about food.
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When you fast intermittently, you don’t cut calories or enter a semi-starvation mode. On the contrary, even though my weight has been reduced, I’m actually eating more now than before intermittent fasting because I don’t want to lose any more. This is an easy way for me to replenish my liver glycogen stores every day and keep my blood sugar at optimal levels, which helps maintain my muscle mass.
All that is required is simply making a firm decision to eat at prescribed times and sticking to them.
Reach Bryant Stamford, Professor of Kinesiology and Integrative Physiology at Hanover College, at [email protected]