Researchers, bless them, have done the obvious at last and published it in the February 26 New England Journal of Medicine (and here’s how USA Today explains the study). They put some intrepid volunteers on 1400-calorie diets varying in content of protein (15-25%), fat (20-40%), and carbohydrate (35-65%) and waited to see how much weight they would lose by the end of two years. Ta-da! The participants all lost a lot of weight in 6 months, but slowly gained it back. By the end of 2 years, they lost about the same amount of weight regardless of the mix. Conclusion: when it comes to weight loss, how much you eat matters more than what you eat. Or, as I am fond of saying, if you want to lose weight, eat less!
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According to Food Chemical News, November 3 (which, alas, only subscribers can read online), the first meeting of the 2010 Dietary Guidelines committee began with speeches from the agency sponsors. FCN quotes Penelope Slade Royall, deputy assistant secretary of health in HHS’s Office of Disease Prevention and Health Promotion (an office in which I worked from 1986-88):
“even when the new guidelines are approved and released in 2010, there’s nothing the committee can do to change people’s behavior…There are very dedicated people across the country working on these [guidelines] and I don’t understand why we’re not more successful.”
Really? I can make some guesses. Why not start by making the guidelines clear, direct, and unambiguous? How about “eat less sugar,” “eliminate sugary drinks,” “eat less fast food,” “eat less often,” and “eat smaller portions.” Or just the mantra of What to Eat: “Eat less, move more, eat fruits, vegetables and whole grains, and don’t eat too much junk food.”
The Department of Health and Human Services has just issued new guidelines for physical activity. They come with a guide for adults, a toolkit for community organizers, and research information for professionals. The approach is easy: some activity is better than none; more is better than less. Seems like good advice (but if you are worried about weight, you still have to eat less).
The New England Journal of Medicine has just published a new diet study that is already causing plenty of debate (see the Wall Street Journal’s take on it, for example). The investigators put about 100 people each on one of three diets: low-fat, low-carbohydrate, and Mediterranean. After two years, everybody lost about 6-10 pounds. The low-carb people did best, the Mediterraneans came next, and the low-fat people lost the least – but the differences were not great. The low-fat diet was not really low in fat (30% of calories) but it doesn’t matter. Everybody reduced caloric intake, increased physical activity, lost some weight, and made some metabolic improvements. One funny thing: the study was funded by the Atkins Foundation but the low-carb people were counseled to choose vegetarian sources of fat and protein, not meat. So this was not a test of the Atkins diet. My interpretation: eat less, move more works, and you have choices about how to do the “eat less” part.
A reader, “rj,” sends a link to an article in Men’s Health (“What if bad fat isn’t so bad”), and asks about: “The supposed inconclusive evidence for sat fat being the culprit in atherosclerosis. Personally, I couldn’t find any credentials of the author but nevertheless would be much interested in your thoughts on the matter.”
My thoughts: As I keep saying, nutrition science is complicated and this article, by an excellent science journalist, is the latest in a series by excellent science journalists (see, for example, the recent books by Gary Taubes and Michael Pollan) to point out the inconsistencies in data on saturated fat and heart disease risk. Let me make several quick points: (1) All fats–no exceptions–are mixtures of saturated, unsaturated, and polyunsaturated fatty acids (2) Saturated fats occur in greater proportions in animal fats–meat and dairy foods, (3) Some epidemiologic evidence–but not all–suggests that people who eat a lot of meat and dairy foods have a higher risk of heart disease than people who eat a lot of fruit and vegetables (this is correlation, not causation), (4) The same clinical studies that show how trans fats do bad things to blood cholesterol levels also show that saturated fat does too, although not as much (But: people take in a lot more saturated fat than trans fat), and (5) Saturated fat is a single nutrient and the studies reviewed and discussed by the journalists take saturated fat out of its dietary context.
Out-of-context studies of single nutrients are exceedingly difficult to interpret. At the moment, today’s dietary (not single nutrient) advice is the same as it has been for the last fifty years. As I put it in What to Eat, “Eat less, move more, eat plenty of fruits and vegetables, and don’t eat too much junk food.” Michael Pollan gives exactly the same advice: “Eat food. Not too much. Mostly plants.” Do this, and you really don’t need to give a thought to single nutrients.
Does this help at all? Thanks for asking.
The World Cancer Research Fund and the American Institute for Cancer Research has just come out with an update on their 1997 report on diet and cancer risk and prevention. After five years of research, the groups have produced ten recommendations. These, no surprise, look not all that different from most other sets of dietary recommendations issued for the last 50 years or so for prevention of chronic disease risk. The recommendations emphasize staying lean and being active (“eat less, move more”). The report will be loaded with data, charts, and references and I’m looking forward to getting my copy. Enjoy!
- Be as lean as possible within the normal range of body weight.
- Be physically active as part of everyday life.
- Limit consumption of energy-dense foods. Avoid sugary drinks.
- Eat mostly foods of plant origin.
- Limit intake of red meat and avoid processed meat.
- Limit alcoholic drinks.
- Limit consumption of salt. Avoid mouldy cereals (grains) or pulses (legumes).
- Aim to meet nutritional needs through diet alone.
- Mothers to breastfeed; children to be breastfed.
- Cancer survivors: Follow the recommendations for cancer prevention.
City University and the Public Health Association of New York City have just released their long-awaited report, “Reversing the Diabetes and Obesity Epidemics in New York City: A Call to Action.” The report focuses on public health–rather than individual–causes of these problems and makes recommendations about how to change the environment to make it more conducive to eating better (less, I call it) and moving more. It’s a good place to go for data on the extent of these problems. Enjoy (?)
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
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.