31 July 12 “Why Calories Count” – Interview with Marion Nestle

Guest post by Donna P. Feldman MS RD of Radio Nutrition

People use MyNetDiary to count calories. But what exactly are calories and why are we counting them? As Marion Nestle points out in the beginning of her new book "Why Calories Count", "You cannot see, taste or smell them. The only way you can tell whether you are getting enough or too many is to observe their effects on your belt size or your weight on a scale."

So if you're looking for background on why exactly calories should be counted, look no further than Nestle's book, which is co-authored with Malden Nesheim. It contains a wealth of information, from the beginnings of nutrition science to the research that documented that food provides us with energy, in the form of calories. She discusses the methods used to determine calories in food, as well as the complex combination of measures used to estimate how many calories a person needs everyday throughout life.

Our current obesity epidemic is inextricably tied to calories, in particular too many of them. The authors discuss how obesity is defined, as well as studies on metabolism, weight loss diets and the social and political contributors to our Eat More society. While this isn't a diet book, it does contain common sense about controlling weight with simple calorie control strategies.

I spoke with Marion Nestle recently about her book.

What is the public's understanding of calories?

Nestle: People really don't have a basic concept that calories are what determine body weight. I just know this from giving talks. They think it matters far more what they're eating than how much they're eating. And so there's almost no intuitive understanding that larger portions have more calories.

What foods in particular do you think are most surprising to people when they see the calorie counts?

Nestle: It's mixed foods. They have no idea about the portions that are served in restaurants. They're totally shocked, if they pay attention to the calorie listings.

What's the best way for people to get an idea of what their individual calorie requirement is?

Nestle: It's not possible to do that accurately. Almost everybody who tries to estimate their own is off by phenomenally huge percentages. It's not something that we recommend at all. If you want to know whether your diet is meeting your calorie needs, you have to weigh yourself on a scale at regular intervals. If your weight is going up you're eating too much. You have to cut back.

What about numbers posted for calories burned, such as with physical activity?

Nestle: It's very, very difficult to use up calories through physical activity. You have to be very skeptical about those machines in gyms. Trainers have told me that those machines are deliberately set to make it look like you're burning more calories than you are. What those people told me is that if they had the real number of calories on the machines, no one would use them because they'd be so discouraged. It's very easy to overeat calories and very hard to work them off.

What do you think of calorie counting apps?

Nestle: If people use them, then they're going to get some ball park idea, but a ball park idea is all you're going to get anyway. If people want to use them, that's fine. There will be some people for whom this kind of information is useful. I don't know how accurate it is, because you don't have the ability to weigh the food you're eating. Any difference in food weight is going to make an enormous difference in the number of calories.

Will restaurant menu labeling help people eat better?

Nestle: It will change behavior for people who look at them. It won't have any effect on people who aren't paying attention. You have to do a huge campaign and bring it to public attention, so people are taught how to use it. People have to know how many calories they're eating and how many they need on a daily basis. For people who do pay attention, it changes behavior. If I see a muffin has 600-700 calories, I won't eat it. I don't want to waste 1/3 of my daily calories on something like that. I know plenty of other people who are stunned seeing how many calories there were in something they thought was much smaller.

Was the obesity epidemic an inspiration for writing this book?

Nestle: The public is demonstrably confused about nutrition. A book that explains what calories are and how they work could be useful. Also, the 2 most important public health problems in the world are either not having enough calories, or eating too many. Calories are involved in the health problems of billions of people.

What is the most important contributor to obesity?

Nestle: Portion size is most important. Food and Agricultural policy is important, but not in an election year. But there is a role for policies that could be effective, such as taxing soda, or Mayor Bloomberg wanting to restrict the size of sodas. These are all policy attempts to try to change the environment, so people aren't exposed to so many calories. We know that individual people trying to keep a on lid on what they're eating doesn't work. We know that. Policy has to come in, if we're going to be effective.

You put less emphasis on physical activity as part of the solution. Do you think it's more of a food calorie issue?

Nestle: I don't think there's any question about it. The evidence is very clear. People aren't less active now than they were 30 years ago. They're eating more. There's so much evidence for that, but there's certainly no clear evidence that people are less active.

What would you say is take away message from Why Calories Count?

Nestle: Larger portions have more calories, so if you want to manage your weight, you have to eat less. If you want to change the environment so it's more conducive to healthier eating you have to get involved in the politics of it. Eat less. Eat better. It's easier to eat less if you're eating better.

Strangely, for the author of a book entitled "Why Calories Count", Nestle doesn't seem to think actual calorie counting by individuals is worthwhile. In her opinion, the results will be inaccurate, so why do it. She thinks the easiest way to monitor calorie intake is by weighing yourself, and then adjusting food intake accordingly. If you want to lose weight, cut back.

My take on this differs. If you are trying to pay attention and control your calories, counting them, whether you use a convenient app, web-based program or a piece of paper and a pencil, is a good way to tune in to what you're eating. Whether or not your daily totals are 100% accurate is not so important. What is important is that you enter your data in a consistent manner. If you feel you aren't losing weight as expected, or gaining unwanted weight, you just adjust food intake so the calories add up a bit lower. Whether or not they're 100% accurate, they will be lower, and that's the real goal.

In fact, given that most scales aren't 100% accurate, and don't always measure important variables like body fat vs. lean mass, monitoring weight as a way to check calorie intake isn't always that useful either.

I also differ with the authors on the issue of physical activity. I think that, while we may overestimate how many calories we burn with exercise, it's never advisable to try to control weight by simply eating less and less. Physical activity is critically important. If anything, the official recommendations are too low to accomplish much. And there's plenty of evidence that exercise has numerous health benefits other than weight management. Unfortunately, our sedentary but over-scheduled lives turn exercise into just another chore, easy to skip when we're too busy.

Despite our differing opinions, I think "Why Calories Count" gives the reader a thorough understanding of what calories are and why we care about them. This book will be useful for anyone looking for more detailed information about this critically important piece of the weight loss puzzle.

Katherine Isacks, MPS, RD, CDE
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