What if I told you that there's a red carpet trick that the stars use to get ready for red carpet appearances like the Oscars and that it's safe, healthy, effective, and free — and you can use it too. That's the claim of a new book by a diabetes specialist who has studied the best way to get his patients off the insulin, free of all their meds, and slimmed down — with a technique called 'intermittent fasting.' His name is Dr. Jason Fung and he gave The Beet a preview of his new book that he's co-authored, called Life in the Fasting Lane.

The book is all about how to use intermittent fasting to lose weight and to do it safely, healthfully, and effectively to slim down in a matter of just days or weeks, depending on how much fasting you want to try. Life in the Fasting Lane is about to hit bookstores and make intermittent fasting, or IF the most followed diet in the country, since it's healthy, it works and you can use it any time you need to lose weight fast.

What is Intermittent Fasting?

Intermittent fasting (IF) is a dietary pattern that uses regularly scheduled alternating periods of eating and fasting to lose weight. There are many different methods of IF which vary the time periods between eating and fasting:

  • Twice a Week (5:2): This method prescribes eating less than 500 calories for two days a week, and ensuring these days are separated by one non-fasting day, in which you eat your regular amount of calories.
  • Time-Restricted Eating (16:8): This method requires 16 hours of fasting and permits eating only within an 8-hour window. This ratio is repeated for as many or as few days per week as you'd like.
  • Eat Stop Eat: This method uses a 24-hour fasting period and is usually observed just once or twice a week.
  • Alternate Day: As the name implies, this method alternates fasting days with days in which you observe a normal, healthy diet. On fasting days, Alternate-Day fasting suggests you cap your calories at a quarter of what you normally eat on a non-fasting day.

How Does Intermittent Fasting Work?

Dr. Fung: "If you fast, and don't eat at all, for 12 or 14 or 16 hours, then your insulin is going to fall – therefore, your body is going to switch over and naturally burn fat. So your body wants 2,000 calories a day, and your body has maybe 200,000 calories stored (as fat). So your metabolic rate doesn't fall, even without exercise. You just start to burn all those stored calories from fat.

"This is proven. Take one study – they fasted patients for four straight days and measured their metabolic rate and after four days of eating zero, they were burning 10 percent more calories than when they ate 2,000 calories a day.

"So if insulin falls, the counterregulatory hormones in the body go up. You activate your fight or flight response, your norepinephrine goes up, and adrenaline goes up, etc., which means you burn more.

"When you go back to eating, your metabolic rate stays the same. You start burning food as fuel. Your body fat is nothing more or less than the body's fuel storage system. But you have to fix the hormone response to food to pull that energy out of storage.

"When we asked patients with Type 2 Diabetes to participate in fasting 24 hours, three times a week, they lost weight and got better. They even got off their meds. And it happened so fast. But you don't have to fast for 24 hours for this to work for you.  You can eat an early dinner, and then not eat until morning or early afternoon and you are essentially doing it, burning fat."

Is Intermittent Fasting Healthy?

Before you shake your head in disbelief and think: "No way is this a good idea," I too was skeptical since I've always believed a healthy diet that is low in calories is the way to go. After editing a health and fitness magazine for over a dozen years and imparting knowledge of how to follow the "fewer calories in, more calories out" way of losing weight the safe and healthy way, when I listened to the science behind fasting, and then read the book, I was convinced that Dr. Fung is onto something.

In fact, fasting dates back to the beginning of humankind when no matter how hungry, humans had to be sharp, strong, and energized to find, forage or hunt for that next meal. Cycling through feast and famine was as natural as cycling through sleep. When Dr. Fung explains the science of how fasting works, he unwound decades of scientific "knowledge" I had held dear. In short, he is extremely convincing. The benefits of IF can include:

"Fasting makes you more focused and helps your mental acuity. You can think a lot more clearly when you're not trying to digest a heavy meal. When you're not eating, everyone thinks it would make it harder to concentrate, but actually, the opposite is true: You can think more clearly. The lion who just ate is sleepy and not dangerous – but the hungry animal is dangerous and can focus on what it needs. When you're full – or you've had a big meal – all you want to do is lie down and take a nap. So when fasting you're super sharp."

How to Lose Fat and Gain Muscle With Intermittent Fasting

One thing to know before you start: There is a way to do it right, and that will help you lose without "yoyo-ing" in energy or weight gain. It all has to do with fuel systems in your body and training your energy to pull from fat and keep insulin levels low so they never tell your body to "store excess energy as fat." Once you get the hang of it, you will burn fat as fuel, all day long.

"If you never let your insulin drop then you never tell your body to pull calories from fat. So there is a whole movement among athletes to train in the fasting state.  If you train without eating, then you need to pull calories out of storage to get through an intense workout. If you eat in the morning – let's say you have a muffin before your workout – then you use up that source and your body never uses calories from fat and your workout was not effective if the reason you're working out is to lose fat.

Here's the great news. whether you fast for 12, 14, or 16 hours or longer it is completely flexible – you could push it up to 16 hours, and do it a couple of times a week. So you eat in an 8-hour window, from 11 am to 7 pm, and then have 16 hours of fasting. A lot of celebrities have talked about IF and how it helped them, like Jennifer Aniston, Reese Witherspoon, and Hugh Jackman. It's really simple. Counting calories and counting carbs are complicated, but timing is simple.

"When people ask me: Is there anything you can eat during the fast? I tell them, Yes. There are variations of fasting. Classic fasting is water only. But there are variations. You can actually do well with all kinds of things: Take tea for example, or coffee with cream, which has fat so there is very little insulin response to that. Just don't put sugar in it. Even if you take something like celery sticks, Insulin would blip up temporarily but go back down. We use a lot of fasting aids, predominantly tea and other drinks. Green tea is very good: The main advantage is the chemical compound called catechin that helps to suppress hunger. The caffeine in both coffee and tea will help your metabolic rate. Keep your metabolism up.

I love to recommend cold brew green tea – or I like to tell patients to try Pique Green Tea which comes in crystals; they brew it and dehydrate it, so it's essentially an instant tea.


"I tell people to cut out snacking [after dinner], so you get to 14 hours. Then you push it to 16 hours. Typically it's a lot easier to drop breakfast than dinner. If you look at circadian rhythms, hunger is usually at the lowest point at 8 am and it's easy to not eat. At that moment you've gone 12 to 14 hours without eating and you're the least hungry. Your body is fueling itself without food.

Can You Eat Anything While Fasting?

"IF works well on a plant-based diet, which is how people ate for many years in Asia. And they stayed slim. It's only when you add processed or high-carb foods that you have to watch out. You have to be careful about the types of foods you eat since processed foods like wheat and flour, bread is now so processed. For bread now they take the wheat berry and grind it into a fine dust. So the absorption is super quick, unnaturally quick. If you eat a lot of cakes and cookies and processed bread and donuts, that will spike your insulin. If you're eating a plant-based diet, make sure to keep it whole-food, plant-based, not processed food.

"So if you're plant-based and eating beans, legumes, vegetables and whole grains like quinoa that all keeps insulin low. If you look at the simple sugars in cereal like Captain Crunch and chocolate donuts that may be vegan but they're terrible for you.

What to Eat to Break Your Fast

Focus on whole foods and healthy plant-based options that are easy to digest when breaking your fast. These include:

  • Cooked vegetables
  • Healthy fats
  • Legumes
  • Nuts
  • Seeds
  • Raw fruits
  • Vegetable broth or soups
  • Vegetable juice

Expert Tips to Start Fasting

1. Start slow

Begin by trying IF for 16 hours, which just means not breaking your fast until lunchtime and beginning your fast again in the evening.

2. Stop snacking and limit your alcohol

Create a strict rule about snacks after dinner which will make it easier to kick off your fast, instead of being tempted to prolong your eating window by having a late dessert or midnight snack. Alcohol is metabolized like sugar, so be sure to limit alcoholic beverages and stop drinking at the same time you begin your fast.

3. Break your fast with whole foods

Avoiding processed food and instead reach for whole foods like fruits, vegetables, nuts, and legumes prevents blood sugar spikes. To break your fast, eat easily digestible foods from the list above.

4. Sip on green tea when fasting

Green tea contains catechin which can help to suppress hunger, so it's a great tool to use while fasting.

Bottom Line: Intermittent fasting is an effective way to promote weight loss.

Before beginning a fasting regimen, it's a good idea to talk to your doctor about any potential risks and choose an IF method that will be the healthiest for you.

If you want to read more from Dr. Jason Fung, get a copy of The Complete Guide to Fasting. And his other book, The Obesity CodeLife in the Fasting Lane is available on Amazon.

For more great expert advice, visit The Beet's Health & Nutrition articles

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