Food Politics

I can’t resist dealing with the questions just asked by Elliot and Johannes.  From Elliot:

A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of coronary heart disease or cardiovascular disease (see: American Journal of Clinical Nutrition, January 13, 2010)…[but] in his book, Good Calories Bad Calories, Gary Taubes clearly attributes most of our chronic disease problems — including heart disease — to carbohydrates (see page 454).  In contrast, Colin Campbell in his book The China Study (pages 113-133) forcefully argues that animal proteins contribute to CVD.  Yet, Dr. David Katz in his book Nutrition in Clinical Practice (pages 130, 133) asserts that to prevent heart disease, “saturated and trans fat should be restricted to below 7% (or even 5%) of total calories . . . .”  Who’s right?  We badly need your unbiased wisdom on this topic.

Joannes says that according to the Weston A Price Foundation,

it seems as if (naturally-occurring) saturated fats are almost better for you than the unsaturated fats we get fed these days, which mainly consist of rancid oils which more than anything contribute to heart disease, whereas many saturated fats are actually quite beneficial.

OK.  Here’s my “unbiased wisdom” (if such a thing exists).  I like to ask: What do saturated fats, sugars, and animal proteins have in common as factors in the development of heart disease?   Answer: They are all single nutrients.

Recall that nutrition research is difficult to do because diets contain many foods, foods contain many nutrients and other chemicals that affect health, and other behavioral, socioeconomic, and genetic factors influence heart disease.  Studies of single nutrients take these chemicals out of their food, dietary, caloric, and lifestyle contexts and are, therefore, reductive.

Such studies tend to produce ambiguous results that demonstrate small differences, if any.  Small differences create situations ripe for interpretation.  Interpretation depends on the viewpoint of the interpreter.  That is why it helps to know who is doing the interpreting and who sponsored the studies.

Short of that, you would have to read every study cited by these authors and come to your own decision about how to interpret them – a daunting task.

My approach to conflicting research?  I look for points of agreement. The authors cited here do not disagree about the basic principles of healthful diets: variety in food intake, moderation in calories, largely plant-based (although not necessarily exclusively), and minimally processed.  Eat according to those principles and you do not have to worry about nutritional details.

All of that boils down to the advice I propose in What to Eat: eat less, move more, eat plenty of fruits and vegetables, and don’t eat too much junk food.

Let the scientists and their interpreters fight it out over single nutrients.  Eat food and enjoy your dinner.

I recently received this request from Daniel posted to Feedback:

Would you mind writing a blog post on the new surgeon general’s obesity report? …Is there a food politic element to why this has gone under the radar? …I find it ironic that Michael Pollan’s Food Rules generated substantially more press than a report by the United States Surgeon General.

I’m not surprised.  Pollan’s book is a hot best seller (it’s #1 on Amazon books, and for good reason, in my opinion).   The need to prevent obesity and how to do it is not exactly front-page news.  And the new Surgeon General, Dr. Regina Benjamin, is still relatively unknown as a political force.

But let’s give Dr. Benjamin credit for taking on obesity in one of her first public actions: the release of “Vision for a Healthy and Fit Nation.“   The Vision, which comes with a press release and a fact sheet, recommends these actions to prevent obesity:

1. Reduce consumption of sodas and juices with added sugars.
2. Reduce consumption of energy dense foods that primarily contain added sugars or solid fats.
3. Eat more fruits, vegetables, whole grains, and lean proteins.
4. Control your portions.
5. Drink more water.
6. Choose low-fat or non-fat dairy products.
7. Limit television viewing time and consider keeping televisions out of children’s rooms.
8. Become more physically active throughout the day.
9. Breastfeed exclusively to 6 months.

These are all useful suggestions but we have heard them before.  The real issue is how to achieve them.  Here, the report disappoints.

The first two items should have grabbed attention: targeting soda reduction as as the first line of defense against obesity, and eating less junk food (my translation) as the second.

But Dr. Benjamin assigns parents the responsibility for feeding kids healthfully.  Fine, but what about about public health approaches to reducing soda consumption?  To pick a non-random example, soda  taxes are under intense debate right now.  Does Dr. Benjamin weigh in on such approaches?  Alas, no.  Only on the second-to-last page does she summarize suggestions from the Centers for Disease Control and Promotion (CDC), among them:

• Increase availability of healthy, affordable food and beverage choices in public service venues.
• Improve geographic availability of supermarkets in underserved areas.
• Improve access to fresh fruits and vegetables by providing incentives for the production, distribution, and procurement of foods from local farms.
• Limit advertisements of less-healthy foods and beverages.

I wish the report had focused on such ideas, instead of leaving them to an afterthought and personal responsibility. It’s great that the nation’s doctor cares about obesity but her Vision isn’t nearly as tough or realistic as it needs to be.  For that, we need the CDC or the report on food marketing to kids that the Institute of Medicine produced in 2005.

In 2001, Surgeon General David Satcher released the first government report on preventing obesity.  It got press. If this one didn’t, it could well be because it doesn’t break enough new ground.  Surely, it’s high time we got beyond blaming parents and instead started focusing on the need to create a food environment that makes it easier for parents and everyone else to make better food choices and be more active.

I hear that Michelle Obama will soon announce (tomorrow?) a new program to address childhood obesity.  I’m hoping that her program will take on some of the factors in the food environment that make it so difficult for everyone to eat healthfully.

Recent news reports encouraged me to take a quick look at the January 2010 American Journal of Clinical Nutrition where investigators have attempted to identify the proportion of human obesity accounted for by genetic variation.  Their conclusion: probably no more than 1% (we used to think it was 5%).  I don’t know why anyone would be surprised.  Obesity rates rose sharply in the early 1980s, with no possibility for so rapid a change in the genetic composition of the population.

I don’t think we need complicated genetic explanations for obesity.  We have so much evidence that people started consuming more calories at about that time and are continuing to do so.  Why more calories?  Portion sizes got bigger, and – hard as it may be to believe – larger portions have more calories!

In a commentary on the study, Claude Bouchard puts it this way:

The obesity epidemic we are facing today unfolded over the past few decades and can clearly not be explained by changes in the frequency of risk alleles. It is more likely due to a changing social and physical environment that encourages consumption and discourages expenditure of energy, behaviors that are poorly compatible with the genome that we have inherited.

Hence: eat less, move more!  And have an active weekend!

For years, some people – not me – have been saying that eating one extra 50-calorie cookie a day can make you put on 5 pounds per year.  This calculation comes from basic math: if about 3500 extra calories make you put on a pound of body fat, then 50 times 365 is 18,250 extra calories which, divided by 3500,  equals about 5 pounds.

This never made sense to me.  It is impossible to know how much you are eating each day within 50 calories let alone how many calories you are using in daily activities.  Yet people used to be able to keep their weight steady without thinking about calories at all.

This is because the body regulates weight and can easily compensate for such small changes in calorie intake or output with small changes in metabolic rate.  It takes more calories to move heavier bodies, and fewer to move lighter ones.

For years, I’ve been thinking that it must take a lot more than 50 extra calories a day – I guessed hundreds -  to make people gain weight.  I thought this for two reasons:

First reason: Portion sizes have increased greatly in recent years, and larger portions have more calories.  Sometimes, they have a lot more.  Foods eaten outside the home often have more calories in them than anyone suspects.

That’s why calorie labeling matters.  Labeling may underestimate the actual calories present in a food according to Tufts researchers (see this week’s Time for commentary and also see the industry response).  But even so, a new study shows that labeling encourages people to cut down on food intake, at least at Starbucks.  Make that two new studies: one from the Rudd Center at Yale comes to the same conclusion.

Second reason: I keep hearing from pediatricians who treat overweight kids that they have kids in their practices who drink from 1,000 to 2,000 calories a day from sodas alone.  I can’t judge whether these figures are correct or not, but several different kinds of studies suggest that many people today are eating a lot more calories than their counterparts of 25 years ago.

Now Martin Katan and David Ludwig have done the actual calculations in a paper in this week’s JAMA titled “Extra calories cause weight gain–but how much?”  Their conservative estimate is that it would take an excess of 370 calories to gain 35 pounds in 28 years.   To become obese in 25 years, you would need to eat 680 calories a day more than you expended.

To become 58 pounds overweight at age 17, they predict that a child would need to overconsume 700 to 1,000 calories a day from the age of 5 or so.

These figures are quite consistent with what those pediatricians were telling me.  By other estimates, average caloric intake has increased by 200-500 calories a day since the early 1980s, along with a 700 calorie-a-day rise in the availability of energy in the food supply (from 3,200 to 3,900 per day per capita).

As Katan and Ludwig conclude:

small changes in lifestyle would have a minor effect on obesity prevention.  Walking an extra mile a day expends, roughly an additional 60 kcal compared with resting – equal to the energy in a small cookie.  Physiological considerations suggest that the apparent energy imbalance for much of the US population is 5- to 10-fold greater, far beyond the ability of most individuals to address on a personal level.  Rather, an effective public health approach to obesity prevention will require fundamental changes in the food supply and the social infrastructure.

This is because on the personal level, prevention of weight gain means eating hundreds of calories a day less.  Moving more, useful as it is, will not do the trick unless people eat less as well.

On the societal level, we need measures to make it easier for people to eat less.

I can think of a bunch of examples.  You?

Investigators at the Harvard School of Public Health estimated the toll of behavioral contributors to early mortality.  Obesity, they say, is the #3 cause of death after cigarette smoking and high blood pressure.

Dutch researchers say smoking is what kills people.  Obesity just leads to disability.

The Robert Wood Johnson Foundation says schools could do something to help prevent obesity if they got their act together.  It provides a guide to doing so.

Adam Drewnowski, my colleague and friend at the University of Washington, says: if you want to understand obesity, take a look at what poverty makes people eat.

And Jeffrey Friedman, an obesity researcher at Rockfeller University tells Nature that obesity is neither an epidemic nor a disease of lifestyle.  It’s all in the genes and in evolution.

I say (see What to Eat): eat less, move more, eat plenty of fruits and vegetables, and don’t eat too much junk food!

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!

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.

I discuss the politics of diet and disease recommendations in my book, Food Politics (now out in a new, expanded edition), and this particular question in “Ask Marion” on Eating Liberally.

Does this help at all? Thanks for asking.