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You're listening to Science Friday on NPR News. I'm Ira Flatow. You're still trying to stick to your New Year's Resolution, losing those 10 pounds like I am, and you're unhappy with your present diet. You know, we all know that dieting is one of the most confusing things we do. There are too many diets out there; you know, somebody swears by Atkins; you know, there's this - this raw food is the way to go; there's the grapefruit diet; maybe even the Mediterranean diet, which is gaining a little bit of esteem there. After all, if you like red wine and olive oil, what's there not to like about that diet?

Well, new research out this week in the New England Journal of Medicine says something really interesting. It says it doesn't matter what diet you chose, and you don't have to single out one program to slim your waistline. It's the calories, stupid, all about the calories. Joining me now is one of the authors of that paper, and if you want to talk about the study, our number is 1-800-989-8255, 1-800-989-TALK. Dr. Frank Sacks is a professor of cardiovascular-disease prevention in the department of nutrition at the Harvard School of Public Health in Boston. He joins us by phone. Welcome to Science Friday.

Dr. FRANK M. SACKS (Cardiovascular Disease Prevention, Harvard University School of Public Health): Thank you.

FLATOW: You know, this is almost like "Back to the Future."

(Soundbite of laughter)

Dr. SACKS: Yeah, you know - I mean, some people have said, well, what's new about this?

FLATOW: Yeah, you know, we used to be - I think it was Jane Brody of the Times used to - saying - writing about nutrition her whole life, saying, a calorie is a calorie is a calorie, and that seems to be what your study says.

Dr. SACKS: Yeah. No, that - well, in the end, that's what it's all about. But you know, to - I mean, when we first proposed the study, and even really lately, there are a lot of people who believe that one diet or another is better, and of course, you see a lot of different diets being promoted as being superior for anybody.

FLATOW: Yeah.

Dr. SACKS: And there is some scientific research that, you know, might - that supports the idea that certain foods, like high protein foods, give you, you know, more of a sense of satisfaction and you won't eat so much at the next meal. And that may all be true, but it certainly doesn't carry through beyond just the few-day period has been studied. So, I mean, there's a good rationale for, you know, for studying different diets with different protein, fat and carb contents.

FLATOW: But your study found that with a lot of people - comparing a lot of people and giving them foods that they would eat - right?

Dr. SACKS: Yeah.

FLATOW: Not starve them on certain diets - that basically, it all depends on the number of calories that you eat and not what form of the calories you're taking in.

Dr. SACKS: That's exactly what the finding was. It was very, very clear result. And we had - it was by far the largest study, 811 people. We conducted it in Baton Rouge, Louisiana, and in Boston. So, you can't imagine two more culturally diverse parts of the United States...

(Soundbite of laughter)

FLATOW: Right.

Dr. SACKS: That has some generalizability(ph). And we went to two years, which you really need to do in a weight-loss study, because after the first six months or so, people tend to regain the weight.

FLATOW: Yeah.

Dr. SACKS: And we found that after a year, people slowly began to regain some weight.

FLATOW: Right. So, on average, how many pounds did they lose on the diet?

Dr. SACKS: On average in the whole group, they lost nine pounds in the two years and about two inches of waistline.

FLATOW: That's not bad.

Dr. SACKS: That's really not too bad, two inches of waistline. That's the average.

FLATOW: Yeah.

Dr. SACKS: And that includes people who didn't, you know, show up for any of the classes, said they didn't want to do it and didn't show back up. So...

FLATOW: And that's what I also found fascinating about your diet, is that you kept this people in. With some people, you allowed them to cheat a little bit. So, you got sort of a real population of the kind of real people.

Dr. SACKS: That's right. That was our idea, that first of all, we wanted to study healthy diets, but reasonable diets...

FLATOW: Right.

Dr. SACKS: Foods that people could choose for themselves, and indeed, they did after the first few months, where they were out there choosing their own foods. And you said it exactly right. I mean, if the diet they were assigned to was not to their liking after awhile, they could certainly change it, and we still wanted them to stay with us because, you know, we wanted to know what happened to them. That's what you're supposed to do in randomized control trials.

FLATOW: You know, I know you're not endorsing any one diet at all, but to me, as someone who's been on Weight Watchers, this sounds sort of like the Weight Watchers diet.

Dr. SACKS: That's right. That's what people tell me. And no, I'm not really endorsing any particular program, but yeah, a nice, sensible program where you pick a healthy diet. You can try to experiment with different sorts of diets, if you like, and our results would support that, because there seems to be no inherent advantage of one versus another.

FLATOW: Were people able to stay on a diet when they're - when you've finished with them, or did they go back to their old habits?

Dr. SACKS: Well, we didn't have the opportunity to see what happened to the whole group when we - you know, when the two-year project was over. But you know, we did contact some of the people, and some have kept the weight all fine. They were actually on NBC and ABC because they want to interview some of our participants. But we've had some good long-term results.

FLATOW: 1-800-989-8255. Let's go to a few calls in here. Katya in Portland, Oregon, hi.

KATYA (Caller): Hello.

FLATOW: Hi there.

KATYA: Hi. I'm a therapist, and I've co-taught with a woman who has lost 125 pounds and kept it off. And what we teach people is to not diet, but to be able to pay attention to their bodies, something our culture teaches people not to. And then they can make better choices, and usually the calories go down and down and down as they find what they really need in the moment.

Dr. SACKS: Oh, I think this is a great idea. I mean, it really makes a lot of sense that - I mean, in order to lose weight, you really have to be mindful of what you're eating and be mindful of your body's responses. I mean, you know, be aware of that, you know, your belly is full; you don't need to, you know, eat another meal on top of the meal, which will just put weight on.

KATYA: Exactly. There's usually a different kind of hunger driving overeating.

Dr. SACKS: Yes, I would agree.

FLATOW: Something more in your brain than in your stomach is what you're saying...

KATYA: Your brain, your heart, your memories.

FLATOW: Yeah. All right, thank you very much.

KATYA: OK.

FLATOW: Take care. 1-800-989-8255. Dr. Sacks, what about the theory that says that fat calories are easier for the body to put on as fat? Does this study to dispute that?

Dr. SACKS: Well, I mean, those are one of a number of kinds of short-term metabolic studies, that - it produced findings that, in this case, would favor low-fat diets, because - I don't dispute that. I don't dispute the fact that if you eat lots of fat, it's easier for that fat to go into your body as fat, if you overeat it. But does that have, really, any benefit in the long run? Apparently, it doesn't. I mean, there may be other countervailing metabolic effects that hadn't been looked at, you know, for this protein in (unintelligible) thing. Well, I don't dispute that that's real very short-term, but again, it doesn't translate to a long-term difference.

FLATOW: Mm-hmm. Let's go to Chris in McLean, Virginia. Hi, Chris.

CHRIS (Caller): Hi.

FLATOW: Hi there.

CHRIS: Well, I just heard the topic today, and it just struck a chord with me because I've tried, I think, every diet under the sun. And then I finally resolved myself that it was a basic calories-in/calories-out, which Dr. Sacks is talking about, I believe, and I started tracking my calories, and forgetting any other type of - category of, like, type of food - whether its brownies I'm eating or, you know, skinless chicken breast and - but just the calories themselves, and I'd read that Lance Armstrong was doing that a number of years ago when he was competing - I guess he's competing again - but it worked for me. I went from 218 to 185 and maintained that weight, which is where I'm supposed to be for my height. And I've maintained that for over two years now. You know, maybe over holidays I might gain a few pounds just because of all the cookies that are available, but...

FLATOW: But you do still watch what you eat?

CHRIS: Absolutely.

FLATOW: Yeah.

CHRIS: And if I get hunger pains, I try to eat a quality food that - for example, acorn squash, OK? Acorn squash is very low in calories, easy to prepare. You can nuke it in eight minutes, an entire squash. It fills you up, it sticks to your bones, it'll carry you through, and it's very low in calories.

FLATOW: All right, Chris, we've got to take another call. Thanks for calling.

CHRIS: Sure.

FLATOW: And Dr. Sacks, it looks like people who want to stay on these diets find their ways of doing that.

Dr. SACKS: Yeah. I mean, the caller just now, he's a very independent, very mindful guy. He really has got the right formula for him and for many other people. I really commend him.

FLATOW: Yeah. How did you find the role of exercise in losing weight? Because everybody who talks about diet says there has to be a certain amount of exercise involved.

Dr. SACKS: Well, actually, exercise is a very well-researched field, exercise and weight loss. And here's what the studies find: that during the weight loss - during the period of weight loss, when you're actively trying to lose weight, exercise plays a small role, a very small role, compared to actually what - the amount of food that you eat. And that's because it's very hard to burn off lots of calories day in and day out, and that people tend to eat back quite a bit of the calories that they burn off. However, in the long run, after you've lost weight, to keep the weight off, exercise is really important, because even a net reduction of 100 calories a day burnt off will have a persistent beneficial effect long run.

FLATOW: Did you - were you able to measure the effects, possibly, on type-two diabetes or insulin production with any of these diets?

Dr. SACKS: Well, first of all, we didn't study - enrolled diabetics into the study because they have special nutritional needs. So - but on the other hand, they were people who you might say were pre-diabetic and they had high insulin levels. So, we found that these diets reduced the insulin levels and maybe especially the diets that were a little lower in carb or, let's say, not the highest carb. The highest carb didn't really reduce insulin levels. This is only for diabetics I'd recommend, you know, a lower carbohydrate type of diet.

FLATOW: Mm-hmm. So, where do you go from here with your research?

Dr. SACKS: Well, I think we, you know, we should move on from trying to figure out what diet is best, because it's probably no diet is best that - the diet is best as the diet that works for each individual person. And I really encourage people to experiment and try different diets and see what - healthy diets and see what they can, you know, keep up with. And I think another very important area of research is to find out why individuals vary so dramatically in their individual response, and I'll give you examples. We have had people who come to almost every one of our group and individual sessions almost every week for two years, and they, on average, did a lot better than the people who didn't come in to any of the groups. But we had some people coming in week after week and not losing a single pound over two years, and then we had some coming week after week and they lose 60 pounds or even more. So, I'd like to try to understand, you know, what's the difference between these people? Is it biology? Is it, say, family environment? I mean, it's sort of the difference in individual response just overwhelms any...

FLATOW: Yeah.

Dr. SACKS: Possible dietary difference.

FLATOW: Especially those people who, I would think, who came in and got all that support and still didn't lose any weight.

Dr. SACKS: I mean, that's amazing. I...

FLATOW: Yeah.

Dr. SACKS: I think they enjoyed the, you know, the social structure of the groups. But you see, then - totally on the other hand, we've had people that would just come to a couple of our sessions early on and then just go off on their own; they're very independent. Most of those did not do well, but a few of them did very, very well and, really, just were able to do it on their own. So, that's the gamut.

FLATOW: Mm-hmm. Interesting. Talking with Dr. Frank Sacks this hour on Talk of the Nation: Science Friday from NPR News. I'm Ira Flatow. Let's see if we can get few more phone calls in, Chauncey(ph) in Tallahassee, hi.

CHAUNCEY (Caller): Hi.

FLATOW: Hi there.

CHAUNCEY: I - OK. I have a comment, and this is something that bugs me, because - first of all, I have recently, recently - in the last year and a half - I've joined a program and a gym. I've lost 65 pounds. I'm 57 years old, and I feel great. But I did not do this by going on a diet; I did it by changing my lifestyle. And I think that that's an issue that a lot of people don't understand, is that, you know, you can't go on a diet, because everything we put in our mouth is a part of our diet.

FLATOW: So, when you say you changed your lifestyle, what do you mean by that?

CHAUNCEY: Well, what I mean is you do things differently than you're accustomed to doing them. For me, it was cutting a lot of fat out of what I was eating and it was, like I said, joining a gym.

FLATOW: Snacking less, less junk food.

CHAUNCEY: Portion control.

FLATOW: Portion control.

CHAUNCEY: Oh, my gosh, is that a biggie, but yeah.

FLATOW: Yeah, portion control.

Dr. SACKS: Well, I think that's the name of the game. I think you did fantastically. I'd recommend it to everybody.

CHAUNCEY: I feel great.

Dr. SACKS: Wonderful.

CHAUNCEY: And I just - but the problem is - like I said, a lot of people say, well, I'm going to go on a diet and drop a few pounds. Well, they do that, and then they're right back to where they were, you know, before they did it. You don't see a lifelong lifestyle change.

FLATOW: What motivation did you have? I mean, what - it takes will power to go on diets. So, it must take will power to change your lifestyle, too.

CHAUNCEY: It's horrible. I am a cook. That's what I do; that's what I love. I learned to do - what motivation? I wanted to get off some - you know, my cholesterol was through the roof; I wanted to change that. I wanted to feel better; I wanted my joints to feel better. And I do. I mean, I go to the gym four times a week. I walk for two to three miles a day. My husband is doing this with me. And you know, we have both seen benefits from making these changes.

FLATOW: And you're still cooking...

CHAUNCEY: I still cook, and I love to cook.

(Soundbite of laughter)

FLATOW: In many ways. Thank you very much, Chauncey. Have a good weekend.

CHAUNCEY: Thank you.

FLATOW: You're welcome. Well, there's - that's how you can do it on your own, Dr. Sacks. You just need the will, right?

Dr. SACKS: Yeah. It's will power, but it's just - just a very commonsense approach, to have portion control, cut out the highest-calorie stuff that you're eating, getting some exercise. It's all an integrated whole.

FLATOW: But we are so bombarded every day, you know, with junk-food commercials and it's all around us. It - you know, it's almost shoved down our throats, so to speak.

Dr. SACKS: It's true. I mean, in fact, there's some - some colleagues feel that the key to their obesity epidemic is, you might say, policy, health policy regulation. But at least what I would say is I'd like to see education. I'd like to see calorie counts be put on foods that you'd pick up in delis or restaurants.

FLATOW: Yeah, interesting. Oh, one I had heard - one theory for burning calories by drinking ice water, because you have to heat up the ice water with your body. If you drink enough ice water, you know, you lose weight.

Dr. SACKS: Well, you know, if you drink water instead of soda, you know, you'll lose weight. Maybe that's the key.

(Soundbite of laughter)

FLATOW: Well, the same person was - we were discussing this, saying, you know, you could go out and freeze, and you're body has to heat up while you're shivering, too. It's not the greatest...

(Soundbite of laughter)

FLATOW: Not the greatest dietary way of losing weight. So, there are a lot of diets around, but what's most interesting is your conclusion is that you count calories, you eat less food and it doesn't matter what kinds of foods you eat if you just eat less of them.

Dr. SACKS: That's right. It really simplifies the message.

FLATOW: All right. Dr. Sacks, thank you very much for taking time to be with us.

Dr. SACKS: Thanks a lot.

FLATOW: Dr. Frank Sacks, professor of cardiovascular-disease prevention in the department of nutrition at Harvard School of Public Health in Boston.

(Soundbite of music)

FLATOW: That's about all the time we have for this hour. This program is produced by Christopher Intagliata and senior producer Annette Heist. Charles Bergquist is our director. Flora Lichtman is our producer for digital media. Our intern is Shelley DuBois. And Neal Rausch is our technical director and at the controls here in New York. We also had help in Second Life from Lynn Cullins, Dave Andrews, Jeff Corbin and the University of Denver. And surf over to our Web site. We're still Twittering. Our tweet is @SciFri. And folks in Second Life are still having a good time there talking to each other. And you can surf over to our Web site where we have Science Friday's videos up there. Still looking for your videos. Our pick of the week is still up there, and we'll look forward to putting a new one up next week. I'm Ira Flatow in New York.

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