Sorting out low-fat vs. low-carbohydrate
October 9, 2007
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.
Yes, we are indeed fortunate to live in a country with so many choices of fresh and prepared foods.
In spite of this, I am amazed at the similarities of the food diaries I ask my patients to keep. They all eat the same breakfast sandwich at the fast food place, they all eat a double cheeseburger and large fries for lunch and they all drink many sodas daily. Or, so it seems. When I ask where are the fresh fruits and vegetables or whole grains, I am frequently told “I can’t afford that.” So, I have started a project to make a display of pictures of foods in 2 categories: a dollar’s worth of food (a dollar being the price of small french fries at the local fast food place) and $3 worth of food (the price of a pack of cheap cigarettes). My point will be to show what a person could have chosen instead, and each display will include the nutrition information for each item. I hope people will be interested to see how much real food they can buy for these money amounts they routinely spend. And, I hope they will see a large number of choices they don’t have to cook, so they might choose to take these foods along in their busy schedules instead of eating as much commercial fast food.
Comment by Sheila — October 9, 2007 @ 9:21 pm
Sheila, that sounds like a great idea! Thinking of maybe mass producing the display?
As a dietetics student, I’m surrounded by people who eat relatively well all the time, so sometimes I feel a bit of a disconnect with what the average person would choose to eat. Today my boyfriend was like, “You’re going to be so proud of me, I didn’t have as much caffeine today!” and when I asked him what he had, he told me he drank as much green tea as he usually would coffee (about 3 cups) and a Pepsi.
Comment by Vincci — October 9, 2007 @ 11:04 pm
At the end of the day, I think the average person just doesn’t have any idea on “how many” calories they eat daily - I try to explain it in terms of “allocation” - “you know where you $ goes, …but where do your calories go?”
Someone needs to pay special attention to what he/she eats for a few weeks before getting the hang of it.
-wahiba
Comment by wahiba — October 10, 2007 @ 11:31 am
I’m not sure Gary Taubes ‘comes down hard’ on carbohydrates. Nor does he claim to solve a problem that ’scientists have been grappling with for decades.’
His point, which he (sometimes laboriously) develops is that scientists were not particularly grappling with scientific questions, but trying to push a point of view. The question wasn’t ‘what works’ but ‘how can we prove that fat is bad’, and that doing otherwise was career suicide.
That effectively squelched any other lines of investigation.
I’m a little puzzled why there is so much research into obesity and diet/health if it all comes down to “eat vegetables and whole grains and move more.”
What the heck are they researching for, anyway?
Comment by WaltK — October 10, 2007 @ 11:37 am
Wow, I’m a graduate student studying climate science and this post reads like a conversation in my hallway everyday. Just replace ‘diet’ with ‘global warming’ and you’ll get the idea. If all of the scientific questions have been answered, what the heck am I doing researching it?
My question, though, is what about traditional diets? I suppose it’s too expensive to eat traditional foods, but I also wonder if they are supposed to be considered good or bad for us now? My great grandmother’s home-grown green bean casserole was full of butter and home-made bacon and tasty extra calories. I would consider it healthy, but I’m not sure what dietitians would think.
Comment by Kate — October 10, 2007 @ 1:02 pm
Oh, so many good thoughts here. WaltK, double - yup!!!!! You got the essence of Taubes’ book. How come others can’t? The low fat crowd doesn’t get it because of their defensive posture (how weird is it that Gina Kolata reviewed the book for the NYT when she is mentioned so unflatteringly in the book? Jane Brody will be the same way).
Sheila, you also hit a nail on the head regarding the perception of the cost of food. Your comment reminded me of a BBC America TV show I like, Ramsey’s Kitchen Nightmares (there is a US version now, too but I haven’t seen it). Gordon Ramsey, over and over finds that restaurants that are losing business and in imminent danger of failing often cut corners with processed, pre-prepared heat-n-serve restaurant supply foods, that in the end are losing them business (because the food doesn’t meet fine dining expectations) and also can cost the restaurant more in the final analysis. He teaches them how to prepare simple, real food that can enhance revenue, be prepared multiple ways, tastes delicious, and cuts costs in the long run. If you can handle the British curse slang, it’s a great show that also has value for home cooks.
Kate, I agree with your comparison of the global warming debate and the low fat diet dogma. Once concensus is achieved (one way or another) further investigation and discussion just seems to stop or only go in one direction. That isn’t good science at all. It is also a waste of money to spend 100s of millions of dollars on one idea. I don’t know what to think yet on global warming, but the debacle for the last 50+ years on the fat hypotheses (actually it’s much longer than that, but 50 years represents a public consciousness of it) has demonstrated how skewed the current science debate can become. Already it just seems that everyone (the public, not necessarily scientists) accepts one simple explanation. That really hit home with me when I saw a commercial for what seemed like a public service announcement on global warming but turned out to be a commercial for Trane or Lennox air conditioners. It’s like Snackwells for global warming.
Comment by Anna — October 10, 2007 @ 2:47 pm
[…] fat from cornfed animals (high in Omega-6s). (New York Times) Related: Nutritionist Marion Nestle comments on the Tierney […]
Pingback by The Ethicurean: Chew the right thing. » Blog Archive » Digest - Features: Grist goes ag-grow, excremental exhortations, and Cal Dining gets SOLE — October 11, 2007 @ 6:57 am
Taubes made the following conclusion in his new book, Good Calories, Bad Calories:
“Carbohydrates make us fat and ultimately cause obesity.”
For me, that “comes down hard on carbohydrates.”
Comment by Bix — October 11, 2007 @ 8:25 am
Dear Bix,
Have you actually read the whole book?
Looks like WaltK did.
Comment by Margot — October 11, 2007 @ 7:55 pm
Hi Margot, I’m working on it!
I think he does come down hard on carbohydrates. Have you read it? Do you think so?
Comment by Bix — October 12, 2007 @ 6:20 am
Even before finishing the book and waiting two years for its publication (I’m reading it as fast as I can), I personally come down hard on carbohydrates, with our without Taubes. Taubes just explains so much more elegantly what I had already discovered (the hard way, unfortunately).
Comment by Anna — October 12, 2007 @ 6:58 pm
Why are whole grains regarded as good? Sure, they break down into sugar more slowly than white bread, but they do break down to the exact same sugar which provokes the exact same insulin reaction, just over a slightly longer period of time.
Yes, there are more nutrients in whole grains than refined, but you can get these same nutrients in higher quantities in meats and other non-grain foods. Even when whole, grains appear to be foods deficient in necessary nutrients and full of risk.
Comment by Mike — October 12, 2007 @ 9:39 pm
Hi Bix and Anna,
No I am not done reading it yet. I am still reading my way through the complexities of the history of all these scientific studies to address the fat or the carbs hypothesis. What struck me immediately, and I think this is Gary Taubes’ first point, is how biased most studies were -especially in the “fat” camp- for ego reasons on the one hand (definitely not for the sake of Science). On the other hand, when politics and press interfere, and personal agendas lead to public health policies that are based on very thin scientific evidence, we are left wondering where Science has gone. Another point Mr. Taubes is making is the over-specialization of scientists, whose studies are biased by their limited lens: e.g. sugars solely studied through the glycemic index lens, or fatty acids through the cholesterol lens.
Today, I had the opportunity to talk to Rob Lustig, who has extensively studied the effects of fructose on insulin (separated from their natural fiber context, and in higher concentrations than in the whole foods form), and makes it a case for the obesity epidemic. I asked him if the facts in Mr. Taubes’ book were true to his knowledge, which he confirmed.
It is very difficult for me at this point not to question the fat hypothesis. Maybe the Carbs hypothesis should be re-named the Sugars and refined Carbs hypothesis.
Let us all keep reading:)
Comment by Margot — October 13, 2007 @ 1:12 am
By the way, Margot, Taubes is not the first to write a book about the weak science underpinning the fat hypothesis, he just has written a more detailed book (I hear it was originally 700+ pages but edited down) and he has a much wider reading audience. If you want to read earlier books, check out Uffe Ranvskov’s The Cholesterol Myths (not as much on alternative or competing theories), as well as the more recent The Great Cholesterol Con by Malcalm Kendrick (a much quicker, easier read). There are others as well, but those come to mind first. Both authors are members of The International Network of Cholesterol Skeptics ( www.thincs.org ). Taubes is not alone in his assertions that the science did not support the public health advisories for everyone to cut the fat.
Comment by Anna — October 13, 2007 @ 12:10 pm
[…] Marion wrote an interesting post today on Sorting out low-fat vs. low-carbohydrateHere’s a quick excerptIntelligent 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 … […]
Pingback by Diet Foods » Blog Archive » Sorting out low-fat vs. low-carbohydrate — October 15, 2007 @ 11:48 am
Dr. Nestle, I think it’s kind of ironic how you say you’re not going to comment on a book you haven’t read, and then you comment on it anyway.
I’m wondering if you’ve finished reading it since you first wrote this post.
You also talk about “50 years of science,” in support of fruits, vegetables, and grains, but of course carbohydrate restriction has been employed to treat obesity for over 150 years. And not all of the science supporting what Taubes calls The Carbohydrate Hypothesis is old, either - there’s still a great deal of insulin research happening to this day.
Comment by Migraineur — November 26, 2007 @ 1:54 pm
I find what Shiela said to be very interesting in that people often times seem off in their rationalization and choices. The debate over low-fat vs. low-carboydrate seems to be very subjective in my opinion. Like Marion said there are so many other factors that affect our bodies it would be hard to say what is the best and what is worst. It does seem apparent that people who eat an excess of fast foods do seem to be less healthy but is this because of the increase fat in a quarter pounder?? Or is it because of a lifestyle of doing whats most convient - which probably isn’t exercising. It is also important to take into consideration that fat contains more calories per gram than carbohydrates so someone who is eating more fats and less carbs should be eating considerably less overall. As Marion states at the end, when you are over-eating by hundreds of calories it doesn’t matter whether your fat is coming from fat or carbohydrates. In the end it is all a balance and people should know their bodies well enough to figure out what is better or worse for them.
Comment by Lou — April 17, 2008 @ 10:59 am
First comment in twelve weeks! I think the book must have been published a little later in UK and Ireland. Nonetheless, I am still reading it.
I find it incredibly informative. Biased? Somewhat but Taubes explains at the beginning that a sense of bias will be noted. In fairness to him, he does present the literature in a very detailed manner.
One of the main points that I have always been interested in is the question of calories. The last point on this board mentioned that at the end of the day, it doesn’t matter what you eat as long as you don’t eat too much of it. This is one of the notions that Taubes set out to disprove. You cannot simply say that eating low-fat brownies, slimline milk and Special K and processed meat is fine as long as the number of calories amounts to a figure less than or equal to that required by the body. This frustrates me so much when I hear people talk about only being “allowed” 1850 calories a day or saying that men should consume 2500 calories a day. It is over-simplified and Taubes is trying to get the point across that the human body does not work the way we would like to think it does, ie calories in vesus calories out.
I myself could probably consume 4000-5000 calories on some days. Yes I exercise every day but if I decided to gorge on healthy food and consume say, 6000 calories on a Sunday, this does not necessarily mean that I am going to put on 200 g of fat. It is so much more complex that that.
Apologies for the rant. Hope I got my point across!
Comment by David — July 9, 2008 @ 10:23 am