What if I told you that there's a red carpet trick that the stars use to get those sleek camera-ready bodies in time for the Oscars and that it's safe, healthy, effective, and free—and you can use 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—fast. 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" coming out this April.

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.

Can Intermittent Fasting Actually be 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.

Here is Dr. Fung's take on how to use IF to empower you to lose weight, get yourself through the hungry moments and not suffer brain fog or lack of energy between meals. The result is that you'll lose weight, have a healthier body, and shed inches without losing tone. Meanwhile, you will see vast improvements in your important health metrics like cholesterol, blood sugar, and blood pressure. I too was a doubter. Not anymore.

How He Discovered That Intermittent Fasting Worked: He Studied Diabetics

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 all of this sounds barbaric, consider that doctors use intermittent fasting to maintain their weight and energy levels during long, grueling hours of rounds when they need to be alert.

Dr. Jason Fung trained conventionally in internal medicine at the University of Toronto and then practiced nephrology—the study of kidney diseases such as diabetes and cancer—while at UCLA. Fung learned first-hand from his patients that obesity creates type-2 diabetes and that diabetes, in turn, leads to kidney failure and then dialysis. "Doctors were treating the kidney failure," and as far as he was concerned "they got it backward. First, they needed to treat the cause, which was obesity. And the best way to do that is to ask your patients to stop eating."

"At first, I practiced like every other doctor practiced in treating Type 2 Diabetes, which is the reason for a lot of the kidney disease we see in America. And the numbers just keep getting bigger and bigger.

"What we were doing was treating patients with medication and insulin and it didn't work. And that impacted a lot of patients I was seeing. And I realized that what we were doing was treating it backward. The causality goes from obesity to diabetes to kidney disease and then dialysis. So we have to treat the obesity -- not the kidney failure -- because if you treat obesity then you can reverse type-2 diabetes. I know this because I tried it. And my patients who did it got better."

Americans in the '60s Did Not Have the Same Rate of Obesity. The Question Is Why?

Fung: "The obesity epidemic dates back decades, and started in the '70s, so it's not really a genetic thing. People had access to food. There was no problem with access to food in the 60s, yet there was no obesity. So people were talking about genetics as a cause, but something else happened. Seventy percent of Americans are obese or overweight today. Consider this: If you see one child fail in school that may be an individual's issue, but if 70 percent of children fail then that's something wrong with the way the school is teaching. So instead of blaming the individual, let's look at the whole system and what's happening.

"The idea that we need to be looking at calories didn't ring true. So that's when I started to look at the hormonal underlying or underpinning reasons -- why are so many people obese. It's not about calories. The body isn't having a response to calories. In fact, 100 calories of soda vs. 100 calories of salmon -- the hormonal response to those are not the same at all. Our bodies respond to hormones. The effect of grilled salmon vs. cola or cookies on your body is completely different.

"Predominantly, we are talking about the insulin response in your body. Insulin tells the body to store fat. When you eat, insulin response goes up, and it tells the body to store excess blood sugar as fat. When you don't eat, like when you sleep, insulin levels fall. So you have to mobilize calories from fat to burn energy to live.If you eat too much sugar or too many carbs, you have to store all those calories as fat. After you do that, there is no energy available -- so you go out and eat more. And again, when insulin goes up again, all the new calories are stored as fat.

Not All Calories Are Created Equal. It's Your Insulin Response that Matters

"Some foods are more fattening and some foods are less fattening. People who eat more salad don't get fat while people who eat more cookies and cake (or any sweets) do get fat. So, the next step is to understand how the hormonal response to the type of food you eat tells your body to store fat or not store fat. This is why people care about the glycemic index of food. The lower the GI, the less your insulin response spikes.

"In the 1930s people were eating up to 2,500 calories a day. Back in 1917, they did studies -- called semi-starvation studies -- where they actually measured what happened when they cut the number of calories a day to between 1,800 to 2,000 calories a day. So they cut calories to that number, which means they had originally been eating more like 2,200 to 2,400 before they reduced for the study. And in the 40s the same thing was true. They cut calories 40 percent to 1,600, so they had been eating more like 2,000 calories a day. And people weren't obese. So it's an interesting paradigm. It's not about the number of calories you eat, but the insulin.

How Do You Get Your Body to Mobilize Fat Stores as Energy?

"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 training 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.

"So I started to understand more about insulin. At that point, when I started my studies on Type 2 Diabetes patients, there hadn't been a lot of people talking about it and I started thinking about fasting. If you want to drive your insulin low then that's going to involve fasting. And I thought 'That sounds like a bad idea.' But then I realized that there is a misconception that your body slows down. That does happen on a low-calorie diet, but not when fasting. You're switching your body over to a new fuel system.

"People who cut their calories and go on a low-fat diet are losing all the dietary fat. If you do that and lower your calories to 1,500 -- you may be lowering your intake but since fat has no effect on insulin, if you have 1,500 calories of bread or pasta, the carbs still stimulate an insulin response.  But, if you eat whole foods that have fat, such as avocado, it won't stimulate insulin. So look back at the low-fat 90s trend in dieting, and insulin gets mobilized by those calories -- even if they are lower calories than you're used to eating.  When you eat a low-fat, high-carb diet, your insulin still responds to the carbs. So you have to reduce your calories in order to draw down fat as energy. Just reducing calories wasn't working. People got fatter.

This is Where Fasting Comes in. You Probably Already Do It Without Even Trying.

"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 4 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 in order 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, the 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.

Breakfast is literally "breaking your fast." You can't break a fast if you aren't fasting.

"Typically people eat breakfast at 8 am and dinner at 6 pm and in that case, we are already fasting 14 hours a day without thinking about it. In the 70s they ate supper earlier. Even if you eat breakfast at 7 am and dinner at 7 pm then you're fasting at least 12 hours a day. This acknowledges that you're supposed to eat in a cycle. There is a certain number of hours in a day when you are supposed to be eating and a certain number of hours when you are supposed to be fasting.

"If you throw your body out of balance and eat from the minute you get up until the minute you get in bed, then you're only fasting for 8 hours.

"If you drink alcohol it is metabolized like sugar, so you have to count wine or beer or spirits in this equation -- so people who drink a lot of wine, they need to know that it's metabolized in the body just like sugar. Two glasses of wine are like having dessert.

"If you want to lose weight, skip the carbs and the alcohol. Insulin gets mobilized the same way, whether it's carbs in food or the sugar in alcohol. People talk about drinking with dinner -- which is reasonable, except if you're trying to lose weight.

How Long You Fast is Up to You. There are Variations, Which Mean You Can Eat!

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 really helped them, like Jennifer Aniston, Reese Witherspoon, and Hugh Jackman. It's really simple. Counting calories and counting carbs is complicated but timing is simple.

"You can push it up to 24 hours of fasting -- you could have dinner and then fast from 8 p.m. until 8 p.m the next night. That's the one-meal-a-day diet. You still are eating that one meal in a day. Eating is not just for sustenance. It's also for interacting with your family and gives you that time to sit down with your family and be social.

"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.

Surround Yourself with Friends Who Are Supportive

"It's important to enlist friends who are supportive. The other thing is to understand about hunger -- because it's going to be most people's pressing concern -- is that it doesn't go up and up. It peaks and comes back down again. When you don't eat, you are going to get hungry...you have to understand that is your body switching over to burning fat.

"Hunger will go up ad then peak and then go down. Hunger has three peaks, breakfast, lunch and dinner. So there is obviously a trained response to when we are used to eating. But if you don't eat, your hunger subsides in a little while. When your hunger drops, whether you eat or not, it's because your body fed itself from its own fat. Your body gets more efficient at pulling calories from fat. So as you fast your hunger decreases over time. People say, "I got used to it." I think my stomach shrank. But your stomach didn't actually shrink. The body just got better at pulling calories from fat. Your body is learning to fuel itself on its own body fat.

"It's now fueling itself so efficiently that you won't have the same level of hunger after the first few times you try it.

How Do You Start Learning to Fast?

"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.

"It 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. So if you eat a lot of cakes and cookies and processed breads 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.

Try Intermittent Fasting for 16 hours. Between 16 and 24 hours twice a week is probably the most popular amount of time. When you get into it for health reasons like diabetes you can go much longer because you've trained your body to know what to do. But always consult your doctor first, of course. Our body carries body fat -- so we can use it. Therefore, if you don't eat you're going to lose it. If you eat all the time you will never lose it.

Celebrities Use IF to Get Red Carpet Ready

"I worked at UCLA and celebrities use this all the time when they have to go on the red carpet. This is an open secret, that everyone does in Hollywood. You can stop eating for several days and get in shape quickly. You can fast and look really good and there is nothing wrong with it. You can look fit. You get rid of all that sugar and your body gets lean. I mean, bears do it -- they don't eat for weeks. Because they have body fat, and so do we.

Ready-carpet ready in days
Getty Images

"Fasting actually 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.

It Makes Sense That If You Want to Lose Weight, You Don't Eat All the Time

"It's a fascinating area because it's the opposite of what people once thought. This research gives people the freedom to not eat. You aren't doing yourself any harm. In fact, you're doing a body good. It gives people the knowledge and confidence to think "I am not hungry and I want to lose weight and so why not skip lunch today?"

"We eat in airports. Schools give snacks all day long. At soccer, kids eat before, during the half time and after the game. We are used to eating before we eat: We have appetizers before dinner. We think we need to eat eat, eat, eat, eat to lose weight. Does that make any sense? No!"

This Makes Sense to Me, Who Had to Unlearn What I Thought I Knew For Years

I thought about this interview. I had heard all these years that reducing below about 1200 calories a day would turn the body onto dimmer mode, lower your metabolism, and cause you to lose weight temporarily but then gain it back the minute you start eating normally again. And that you would have successfully lowered your metabolism in the process. The fact that the body works on an "on" and "off" switch due to insulin response to the food we eat makes sense.

I thought about my mother who was always preternaturally thin. When she had a big day of eating she would intuitively stop eating the next day, and pat her nonexistent belly and say: I feel full from yesterday. Then she would start eating again when her appetite came back, usually about 24 hours later. She intuitively knew that intermittent fasting worked for her. She never held back what she wanted or loved: Ice cream and pasta and wine. Then she would flip a switch and not eat for a day or so. She never gained weight, never lacked for energy and would work hours into the night on her paintings and always had a cup of black coffee nearby. This may be the "new" way of dieting but it's been around forever.

I tried it, and I am trying it still. IF does give you a sense of power, that you can have your delicious lunch of Beyond Sushi (true story) then a light dinner with my husband (he had a burger while I had a spinach salad with mushrooms, a glass of red wine, and half his fries) then turn off the eating from 9 p.m. until about lunchtime the next day. I went running -- hill repeats with my triathlon team at 6 a.m. -- and ordinarily, would have had half of a banana or a handful of blueberries before heading out the door.

After my hill run, ordinarily, I would have nibbled on a bagel or breakfast cereal. Instead, I drank my black coffee and resolved to wait to eat until later. I'm not good with hunger as I get "hangry" and never thought that "depriving myself" was a good thing -- it flies in the face of my feminist sensibility that I always had to watch my weight when my brother could eat Doritos all day and never have to worry?

Then I realize if you watch fit, slim, healthy people, they often cycle through their eating habits. They usually eat with abandon one day and then fast the next. Even as toddlers, my kids were like this. One day they would eat enough for two people, then lose all interest in food the next. This seems like a natural human state: indulge, then hold back. Or eat when hungry, and then don't eat for stretches when hunger subsides. I never used to "skip" a meal. Now I see intermittent fasting as a chance for my body to self-regulate, and so far I'm enjoying this new way of giving myself a chance to be both satisfied (with the food I eat) and healthy, and maintain a weight that fits my clothes, my lifestyle and my desire to be active and fit. Try it, do it your way, and let me know what you think.

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 Code." Life in the Fasting Lane is available for pre-order on Amazon.

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