IRA FLATOW: This is Science Friday. I’m Ira Flatow. I am one of those people who made a New Year’s resolution to change my diet, not just to go on diet, but to change what I eat and the way eat. And I went looking through diet books and believe me, we get a ton of diet books here in our office. There’s lots of books by Michael Pollan. Remember his mantra, eat food, not too much, mostly plants. Good advice.

But what enticed me about my next guest’s advice was the title of his book, Always Hungry. It spoke to me. Yes, always hungry. As I read the book it explained why. And the problem boil down to my fat cells. You see fat’s not just some gloopy innard blob you’re trying to get rid of. It’s alive, and releases and responds to chemical signals in the body. It’s even looped in with your immune system, and can cause inflammation if you don’t treat it right.

And this diet does not count calories. Yay. It lets you eat as much as you want once you’ve retrained your fat cells. Dr. David Ludwig is author of Always Hungry. He’s a practicing endocrinologist at Boston’s Children Hospital, professor of nutrition at the famed Harvard School of Public Health. Welcome back to the program, Dr. Ludwig.

DAVID LUDWIG: Thank you, Ira. Great to be with you again.

IRA FLATOW: And we have an excerpt of your book at sciencefriday.com/alwayshungry. David, always hungry. What was the catalyst for calling it that?

DAVID LUDWIG: Well what is the most difficult problem that arises on a diet? People get hungry. And according to the conventional model, we’re supposed to ignore the hunger, use discipline, and stick to the diet. And if you just do that it’s really so simple. If you just do that, eat a little less, move a little more, you’ll be able to manage any kind of weight problem over time.

And because it sounds so simple, people who can’t do it, which are 90% of the country or more with a weight issue, people can’t do it are blamed for the problem. It must be at the very least poor willpower or discipline, or possibly a character issue. And of course, in our society we stigmatize people for this particular medical issue in ways that we don’t for virtually any other.

IRA FLATOW: The real star of your book, the lead protagonist may be the fat cell. Tell us why we have such mythology about being fat in the fat cells.

DAVID LUDWIG: OK, well the basic premise of the book is simple, although provocative. Overeating doesn’t make you fat. The process of getting fat makes you overeat. Now that sounds provocative, but it’s actually based on decades, if not a century of research to say that body weight is really much more about our biology than our will power behavior.

So something has triggered our fat cells to suck in and hoard too many calories. The fat cells are in communication with the bloodstream, and they actively can either take in or release calories. But if fat cells are driven into a feeding frenzy, in effect, they hoard too many calories. They hold onto them. The calories can check in. They can’t get out. And there are too few in the bloodstream.

So the brain recognizes that as a metabolic crisis. It doesn’t see that there’s too many calories in the fat cells. It’s really a distribution problem. It’s not in the right place in the bloodstream and available to fuel the needs of the body. So the brain does what it’s supposed to do, what it’s evolved to do, which is it makes us hungry and it slows down metabolism making us more and more efficient.

Cutting back on calories only makes the situation worse, creating a battle between mind and metabolism that were destined to lose. So really, the solution is to think about weight issues like we do about any other problem controlling a basic body system. There’s something biologically wrong. How did it happen? And what can we do about it?

IRA FLATOW: So you have to retrain the body and the fat cells in it to release the energy that’s stored up and get rid of those fat cells.

DAVID LUDWIG: So the issue is– we argue that the low fat diet, not necessarily every low fat diet, but the low fat diet we’ve been eating the United States for the last forty years, which was loaded with processed carbohydrates, right? We think of up until very recently we were told that a healthy breakfast might be a bagel, fat free cream cheese, and a glass of juice. These foods, these highly processed carbohydrates, raise blood sugar more than would ever happen throughout human evolution eating natural, less processed foods. The problem with that is it causes a massive outpouring of the hormone insulin. They call insulin the Miracle-Gro for your fat cells, but it’s not the kind of miracle you want.

So think of what happens in type 1 diabetes, that’s juvenile onset diabetes. Children come in without enough insulin, and there invariably going to be suffering weight loss. They might be eating 5,000, 7,000, 10,000 calories a day, they’ll still be losing weight. Without insulin, you can’t gain weight. If you treat them with insulin, they’ll get back to normal weight. If you over treat them, they’ll inevitably gain too much weight.

So the premise of the book is that the highly processed carbohydrates we’ve been eating and a few other dietary and lifestyle influences has caused hormonal changes in the body, especially involving insulin, that drive fat cells into a feeding frenzy. So they feast. The rest of the body starves.

We think of obesity as a state of excess, but it’s really an issue of starvation to the body. And cutting back on calories makes that worse. So instead, we proposed a much higher fat diet, a three phase program, and some other dietary changes, and some lifestyle supports that also help the fat cells calm down.

When that happens, the calories flood back into the body. You feel much more energetic, cravings decrease, energy expenditure increases. And you start losing weight with your body’s cooperation, not against it.

IRA FLATOW: I found it to be have elements of the Atkins diet in it.

DAVID LUDWIG: Well this does involve the same principles as very low carbohydrate or ketogenic diets, but this is not that. The phase one, we eliminate grains, potatoes, and added sugar for just two weeks. Phase two we add back whole kernel, unprocessed grains. And then in phase three, you get to start adding some of the more processed carbohydrates, but based on your body’s ability to handle it. People differ in how they manage that.

Let me give you an example of what– a metaphor for the conventional approach. So we tell people just eat less. And they get hungrier, and their metabolism slows down. We’ve known that for years.

It’s like considering fever a problem with heat in, heat out. We hear the whole calorie in, calorie out. Imagine somebody said, you know fever– we don’t know what’s really causing it, but it’s just simply heat in, heat out. So we just got to remove heat from the body, take an ice bath. So imagine how you would feel if you had a fever, and you got into an ice bath. First of all, you probably wouldn’t do it. If you did, of course your body temperature would drop, but your body would fight back with severe shivering, blood vessel constriction, and you’d feel miserable.

That’s, in a sense, what’s happening with our treatment of obesity. It’s missing its symptomatic treatment. And it’s causing the body to fight back harder and harder, as well it should if the basic problem is there aren’t enough calories in the bloodstream. So this approach targets the source of the problem, which is fat cells on calorie storage overdrive. Once they calm down and stop storing too many calories, weight loss occurs without struggle.

IRA FLATOW: I do think that you could cure some people’s type 2 diabetes on this diet?

DAVID LUDWIG: Well we know the type 2 diabetes in its early stages is fully reversible. It happens in the majority of people who undergo bariatric surgery. And I think in principle, there’s no reason that diet can’t do the same.

And we used to call type 2 diabetes carbohydrate intolerance. And yet, the standard treatment for type 2 diabetes for the last 50 years has been a high carbohydrate diet. Somebody with lactose intolerance is told not to eat things with lactose. Why do we give so much carbohydrate to people with carbohydrate intolerance?

IRA FLATOW: But you don’t do away with all carbohydrates? You try to find and you actually create recipes in your book for [INAUDIBLE]–

DAVID LUDWIG: That’s right. I think there may be– and this is an exciting area of research. To the extreme low carbohydrate is called the ketogenic diet. And with essentially no carbohydrate, the body shifts into a different mode. In fact, the brain becomes adapted not to using much glucose at all. And it can live on ketones.

Some people are claiming ketones are a sort of super fuel that brain loves. It actually can be effective in preventing seizures in children. Some people are talking about it as anti-inflammatory and even anti-aging. But that’s a very extreme diet. You can’t even have much of any fruit, let alone grain products or starchy vegetables or the like.

I think for most people– most people can do perfectly well as long as we target the highly processed carbohydrates. In other words, you can get most of the same effects but with a much more easily adaptable diet that doesn’t require the nation of any major nutrients at all.

IRA FLATOW: What about fiber? We keep hearing that our microbiome lives on fiber. Is that key in your diet?

DAVID LUDWIG: Yeah. We like fiber. And even though that we certainly have options for mediators, there is a lot of plant foods, whole plant foods, which provide fiber, which serves as a fertilizer for our internal garden, the gut microbiome. So fiber is a key part of it. That’s called prebiotics.

Probiotics are the good bacteria that you get in yogurt or naturally fermented foods. And then, polyphenols are sort of like a weed killers. Polyphenols are the chemicals in plants that typically have color and oftentimes flavor, things like turmeric, the herb, the spice. And these polyphenols tend to target the harmful bacteria, while leaving the helpful bacterial alone. So prebiotics, probiotics, and polyphenols are a way to grow a healthy internal gut flora, which we now are discovering really key to health and weight maintenance and chronic disease prevention.

IRA FLATOW: Now, what I found also interesting in your book is that you make no distinction in artificial sweeteners and regular sugar. And I know they’re different, and you talk about that. But you say that the body may not know the difference, and may get just the taste of sweetness. Even an artificial sweetener may trigger your body to act as if it sugar. And that’s a bad thing.

DAVID LUDWIG: Yeah, let me just fine tune that message, just slightly. I think that the research and we’ve done– my research partner, Cara Ebbeling, and I and our group here in Boston have done a number of studies looking at sugary beverages versus non-caloric beverages on body weight and children and young adults. And it does seem from our research and others that if you have a weight problem and you get off of sugar onto the diet beverages, diet or artificial sweeteners, your body weight will improve.

But that leaves the big question open. How did these artificial sweeteners compare to natural boundaries, unsweetened beverages pr mineral waters and the like? And we don’t know, but there’s reason for concern because they bind the sugar, the sweetness receptor that’s in the mouth, but also throughout the digestive tract and even on fat cells. Fat cells have sweetness taste receptors. They can bind them and cause metabolic changes that signal the brain and signal the fat cells in possibly harmful ways.

So we’ve got some interesting research studies pending. But I think for the moment, the safest approach is to think of these artificial sweeteners as at most a transitional tool to get you off of the highly sugared stuff.

IRA FLATOW: In your book it also talks about your body, your fat cells being linked to the immune system. How does that happen?

DAVID LUDWIG: Absolutely. Well let’s put on the perspective of being a bacteria. Fat cells, the fat tissue in our body is the most prized source of nutrition for invading microbes. They would love to go to town on our fat tissue. But why is fat so rarely infected? It’s because it’s under constant surveillance from the immune system. White blood cells are continuously traveling through fat cells looking for any possible invading microbe. And in fact, the fat cells themselves and the white blood cells send messages to each other.

What happens in obesity with insulin resistance is that the fat cells start to overgrow their blood supply. Some of them may actually suffer dysfunction or even die. They start releasing warning chemicals. More white blood cells rush in. And it creates inflammation, but in this case, there’s no bacteria to kill.

That information becomes chronic. Fat tissue then starts secreting into the rest of the body these toxic inflammatory substances. When that information spreads to the lining of the blood vessels it can contribute to atherosclerosis and heart attack. When it goes to the pancreas it can contribute to diabetes. If it goes to the brain, neurodegenerative diseases. We’re now seeing an epidemic of Alzheimer’s, which some people are now calling type 3 diabetes.

IRA FLATOW: I’m Ira Flatow. This is Science Friday from PRI, Public Radio International. Talking with Dr. David Ludwig, author of Always Hungry. I’m actually going to try this book out.

[LAUGHTER]

DAVID LUDWIG: Good.

IRA FLATOW: Because I want– it has recipes for it inside. You really have to be diligent it looks like, because there are charts and graphs. And you not only talk about food, but you talk about your mind and having to get sort of into a mindfulness state to some degree.

DAVID LUDWIG: Yeah, let me just say in terms of how difficult, yes, we do have to make changes. And the first thing that we suggest, we walk the reader through this, is a home clean out. It’s a good time of year for the home cleaning out. Get rid of the unhealthy– there’s so many toxic influences around us in society. At least we can create the home as a bastion of protection, little sacrosanct area where when we’re eating there, we’re moving in the right direction.

But because this doesn’t restrict any major nutrient, it’s inherently easier to follow. And I’ll have to give credit to my wife, who is a gourmet natural foods chef and educator. She oversaw all of the recipes and meal plans. And she’s a busy working mother. And so we made it a point that all of the dinners can be made– essentially all of the dinners can be made in 30 minutes or less. Lunches in 20 minutes or less. Although you prepare a bit on the weekends.

This is a rich, high fat diet full of nuts, nut butters, full fat dairy, avocado, dark chocolate.

IRA FLATOW: We’re going to try it out. Dr. David Ludwig, author of the new book Always Hungry, professor of nutrition and Harvard School of Public Health. Thank you be joining us today.

DAVID LUDWIG: Great to talk to you.

IRA FLATOW: We have an excerpt at sciencefriday.com/alwayshungry. We’ll be right back after this break.

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