by Marion Nestle

Currently browsing posts about: Eat-less-and-move-more

Oct 9 2007

Sorting out low-fat vs. low-carbohydrate

Several people, among them Kerry Trueman of Eating Liberally, asked my opinion of John Tierney’s column about Gary Taubes’ new book, Good Calories Bad Calories, in today’s New York Times. Taubes’ book arrived while I was in India and I can’t really comment on it until I have had a chance to read it. I gather from Tierney’s piece and Gina Kolata’s review of it on Sunday that it comes down hard on carbohydrates.

I continue to be impressed by how difficult it is to separate the health effects of fat, carbohydrate, and protein from the calories they provide, the foods that contain them, the diets as a whole, or the rest of the lifestyle that goes along with the diet. Finding out what people eat is hard to do. Determining the health effects of dietary factors or patterns is even harder since humans make such awful experimental animals. Plenty of things about human nutrition are reasonably well established–the basic nutrients that are required and the amounts that prevent deficiency diseases, for example. But it is much trickier to figure out the effects of nutrients on chronic diseases that are also affected by activity levels, cigarette smoking, alcohol use, and social factors such as poverty, stress, and lack of control. So I can’t help but be skeptical of journalists who think they have answers to questions that scientists have been grappling with for years.

In a situation in which questions remain, is it better to say nothing or to give the best advice possible based on existing knowledge? Intelligent people may differ on this point but I am convinced that people really want to know what diet is best for their health and want help making food choices. What seems amazing to me is that despite decades of arguments over fat v. carbohydrate, basic dietary advice for preventing chronic diseases hasn’t changed in 50 years. I summarize this advice in What to Eat as don’t eat too much (eat less, move more); eat plenty of fruits, vegetables, and whole grains; and don’t eat too much junk food. This seems like a pretty good approach backed up by plenty of research.

Oh, and the calorie question. It’s not that people are overeating 50 to 100 calories a day (the amount in one or two Oreo cookies) and gaining weight. Most bodies can easily compensate for small differences in caloric intake and output. But, as I hear from pediatricians all the time, kids these days are consuming hundreds of calories more than they need, and sometimes thousands. Metabolism–in kids or adults–just can’t handle that level of overload. In that situation, carbohydrates may be harder to handle than fats, but both will end up in the body as fat if those calories aren’t used up in physical activity.

Fortunately, my precepts leave plenty of room for enjoying delicious food, and aren’t we lucky to have so much around.

Aug 30 2007

We’re Smart: How Come We’re Gaining Weight?

A comment on my August 15 post, “Playing With Obesity Maps” (click on Obesity), asks: “…can you “weigh in” on…the fact is that the nation’s getting fatter even though there’s so much information available out there that should make these numbers go down instead of up?”

Sure. Happy to. We like to think that knowing what to do to stay healthy would be enough to make us do it and it would be great if it did. But mere mortals need more help than that. That’s why the social environment is such an important influence on what we do. Right now, we have a social environment that encourages us to eat more (larger portions! food everywhere!) and move less (computers! remotes! cars! elevators!). As individuals, we fight society when we try to eat less and move more. So education, which is easy to do, rarely turns out to be enough. We have to change society–and that, of course, is not so easy, not least because doing so runs up against a lot of vested interests.

Aug 30 2007

What’s My Take on Diet Books?

That same commenter had a second question: “What’s your take on all the diet books that are out there these days?”

I’m not sure which ones you mean in particular, but it doesn’t matter. They are all pretty much the same. They promise that if you just do this one thing, weight will pour off. All of them work–for some people, for some period of time. All of them say they are easy to follow and are a breakthrough, and all provide a semblance of biological rationale (some better than others). Whatever the gimmick–low fat, low carbohydrate, high volume of fruits and vegetables, low glycemic index, whatever–all have to be based on some method to reduce calories. Calories count. That’s why it matters to eat less and move more. Diets that suggest “eat more” fruits, vegetables, and whole grains, however, do make sense. But the ones that suggest eating more fat usually don’t (because fat has more concentrated calories). Whatever the diets suggest, they are unlikely to be harmful for a few weeks.

Aug 29 2007

F as in Fat: More Obesity in America

The Robert Wood Johnson report on climbing rates of obesity awards the prize to Mississippi as the first state to reach 30% of the population as overweight. The most distressing finding: rates are rising in one-fourth of the states, with the highest rates in the south. What to do? “Make healthy choices easy choices,” says the report. Good idea: make it easier for everyone to eat less or better and to move more.

And here’s what the New York Times had to say about this.

Aug 20 2007

Type 2 Diabetes is Now Controversial?

Today’s New York Times has a front page story by Gina Kolata, who seems to make a career of taking contrary positions on commonly held ideas about health matters. This time, she takes on common understanding of type 2 diabetes. Her article appears to argue that people with type 2 diabetes do not need to worry nearly as much about high blood sugar as they do about high blood cholesterol, that they need a mountain of drugs to stay healthy, that obesity isn’t really related to this condition (genetics counts more), and that rates of type 2 diabetes are not increasing, anyway (it’s just being diagnosed more frequently). Statisticians are unlikely ever to agree on the numbers but type 2 diabetes is the best reason I can think of to follow my “eat less, move more” mantra. Type 2 diabetes is a largely preventable condition. Yes, only small percentage of overweight individuals will develop type 2 diabetes, but the probability of getting it increases with increasing body weight. And if you look at the body weights of people who have been diagnosed with type 2 diabetes, most of them–95% in some studies–are overweight. It doesn’t take much of eating less and moving more to prevent or resolve symptoms. And that works for high blood cholesterol, as well.  Doesn’t doing that seem better than being tied to a lifetime of pharmaceuticals? And what about type 2 diabetes in young children? Isn’t type 2 diabetes something that everyone ought to be trying to prevent? I wrote about these issues in an editorial in the American Journal of Public Health a couple of years ago. Read the references to it and see how they compare to the this-won’t-work attitude expressed in Gina Kolata’s article. Will her article help clear up public confusion about how to approach chronic diseases related to diet and activity levels? Do weigh in on this one.

Aug 17 2007

Nutrition Policies to Prevent Cancer?

A most unusual presidential panel on cancer prevention, sponsored by the National Cancer Institute, has just weighed in with a report asking for better policies to make it easier for people to eat more healthfully. The Washington Post views the report as taking on the food industry (also tobacco). It quotes the chair of the panel as saying that the country has a moral obligation to protect the health of Americans. Indeed it has, but it is surprising that a panel reporting to this president puts so much of the responsibility for healthful eating on the food industry. The report itself is worth reading for its strikingly candid comments–“Ineffective policies, in conjunction with limited regulation of sales and marketing in the food and beverage industry, have spawned a culture that struggles to make healthy choices – a culture in dire need of change”–and its emphasis on the need to eat less and move more (my philosophy, precisely). The committee had only three members: it’s chair, Dr. LaSalle Leffall of Howard University, Margaret Kripke (M.D. Anderson Cancer Center, University of Texas), and none other than Lance Armstrong.

Aug 11 2007

Can Foods Be Ranked Nutritionally?

A comment posted yesterday under the Label category asks whether it is possible to rank foods: “The idea that I’m trying to express is some measure that shows that 100 calories of, say, broccoli sauteed in olive oil is healthier than 100 calories of shortbread cookies or 100 calories of potato chips, even if they happend to have the same number of fat grams.”

I have philosophical as well as practical problems with this kind of approach. First, the practical: Foods contain 40 to 50 components known to be required in the human diet and hundreds more (antioxidants, for example) that are not considered essential but have effects on health. All foods except sugar–which has calories but no nutrients–have lots of different nutrients, but in different proportions. Once you get beyond soft drinks, the situation gets really complicated. Many groups have taken this on: Center for Science in the Public Interest, Hannaford supermarkets, the Australian Heart Foundation, for example. I think they are way too complicated and the cut points set up a slippery slope. If you rank foods high because they contain vitamins, all companies have to do is add vitamins to their products to make them rank higher.

Philosophically, I much prefer the “eat less, move more, eat lots of fruits and vegetables, and don’t eat too much junk food” approach. Because there are so many different nutrients to keep track of, and because foods have nutrients in different proportions, eating lots of different kinds of relatively unprocessed foods takes care of nutritional needs. Keeping junk foods (highly processed by definition) to a minimum means that you don’t have to worry about the nutritional details and can enjoy what you eat.

Thanks for asking!

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