by Marion Nestle

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Jul 7 2016

More on carbs vs. fats: The NuSI study*

Yesterday I explained why “butter is back” is not useful dietary advice, even when studies show that eating butter has little or no effect on disease risk (the total diet and calories are what matter).  Now I can say the same thing about low-carbohydrate diets.

The debate about whether fat or carbohydrate is responsible for obesity has passionate advocates on both sides, although those for carbohydrates predominate in the press these days.

As explained by Julia Belluz of Vox,

The main scientific model behind the low-carb approach is the “carbohydrate-insulin hypothesis,” which journalist Gary Taubes, Harvard professor David Ludwig, and others have extensively promoted. It suggests that a diet heavy in carbohydrates (especially refined grains and sugars) leads to weight gain because of a specific mechanism: Carbs drive up insulin in the body, causing the body to hold on to fat and suppress calorie burn.

According to this hypothesis, to lose weight you reduce the amount of carb calories you eat and replace them with fat calories. This is supposed to drive down insulin levels, boost calorie burn, and help fat melt away…instead of just cutting calories, you’re supposed to change the kinds of calories in your diet to lose weight.

To his great credit, Gary Taubes was willing to put this hypothesis to the test.  He organized the Nutrition Science Initiative (NuSI) to fund studies that he must have hoped would demonstrate the benefits of low-carb diets.

To its great credit, NuSI recruited highly experienced and respected obesity investigators to design and conduct the studies.

The first of these studies has just been published.   It fully discloses the role of NuSI.

Supported by the Nutrition Sciences Initiative…Nutrition Sciences Initiative (NuSI) convened the research team, helped formulate the hypothesis, and provided partial funding. NuSI and its scientific advisors were given the opportunity to comment on the study design and the manuscript, but the investigators retained full editorial control.

In this case, because I am familiar with the work of some of the investigators, I’m inclined to take these statements at face value.

Here’s what they did.  They put 17 overweight or obese men in a metabolic ward and fed them a very low carbohydrate diet, so low that it would induce fat breakdown and ketosis.  The calories were supposed to be sufficient to maintain weight, but were not.  The men lost weight from water excretion and breakdown of body protein as well as of fat, as is typical of what happens during partial starvation.  Energy expenditure did not increase to the level anticipated from the carbohydrate-insulin model.

The Abstract concluded:

The isocaloric KD [ketogenic, very low carbohydrate diet] was not accompanied by increased body fat loss but was associated with relatively small increases in EE [energy expenditure] that were near the limits of detection [translation: barely detectable] with the use of state-of-the-art technology.

The Discussion concluded:

Therefore, our data do not support the carbohydrate–insulin model predictions of physiologically relevant increases in EE or greater body fat loss in response to an isocaloric KD. However, it is possible that dietary carbohydrate restriction might result in decreased ad libitum energy intake—a prediction of the carbohydrate-insulin model that was not tested in the current study but deserves further investigation.

In other words, restricting carbohydrate does not increase body fat loss or energy expenditure but might help you eat fewer calories.

This result confirms some of the results of a previous study from the first NuSI author. That one, funded by NIH, concluded:

Whereas carbohydrate restriction led to sustained increases in fat oxidation and loss of 53 ± 6 g/day of body fat, fat oxidation was unchanged by fat restriction, leading to 89 ± 6 g/day of fat loss, and was significantly greater than carbohydrate restriction (p = 0.002).

Taken together, these studies show that both low-carbohydrate and low-fat diets cause weight loss when calories are restricted, but low-fat diets cause greater losses in body fat content than do low-carbohydrate diets.

In my book with Malden Nesheim, Why Calories Count: From Science to Politics, we review a 1964 study that put obese patients in a metabolic ward and fed them low-calorie diets of widely varied composition.  They lost weight at the same rate on diets ranging from 3% to 60% carbohydrate and from 13% to 83% fat.  They titled the study “Calories Do Count.”  The NuSI studies confirm the benefits of reducing calories from any source to lose weight.

Bottom line:

  • With regard to weight loss, calories count and the relative proportions of fat, protein, and carbohydrate do not matter much (although low-carb diets may help with eating less).
  • With regard to health, the food sources of calories matter very much indeed, and nearly everyone would be better off eating less sugar—at the very least because sugars provide calories, but no nutrients.

*Note: this version corrects an error in the version originally posted.  Hall et al.’s 2015 study was funded by NIH, not NuSI.  Apologies.

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Jul 6 2016

No, butter is not back (eat in moderation, please)

I like butter as much as you do—and definitely more than margarine—but Time Magazine took it to an extreme with its cover story last year on how scientists (they are so dumb) got it wrong.

Hype alert: any time you read that science got it wrong, be skeptical.  Maybe they did, but it’s more likely that the science is still incomplete.

Time Magazine is really dug in on the butter issue.  It continues to insist that scientists were wrong about saturated fats.  Indeed, Time says, its case against saturated fats has just gotten even stronger.

On what basis?  A new study with the provocative title, “Is butter back?”   The study concludes:

This systematic review and meta-analysis suggests relatively small or neutral overall associations of butter with mortality, CVD, and diabetes.

It comes as no surprise that a single food like butter is not linked to a higher risk of heart disease. The highly respected Cochrane Collaboration’s meta-analysis of 15 randomized clinical trials concluded that replacing saturated fat (from all sources) with polyunsaturated fats lowers the risk of heart attacks and other cardiovascular events. (That finding is consistent with clinical studies on blood cholesterol levels and well-designed analyses of observational studies). One would not expect any single food to matter, since people who eat butter don’t necessarily eat an overall diet that is high in saturated fat.

No, butter is not back says the Harvard School of Public Health:

What the headlines miss is that in a meta-analysis such as this, there is no specific comparison (i.e. butter vs. olive oil), so the default comparison becomes butter vs. the rest of the diet. That means butter is being compared to a largely unhealthy mix of refined grains, soda, other sources of sugar, potatoes, and red meat…Here is the most important takeaway from this study not making headlines: Butter, a concentrated source of saturated fat, is still a worse choice than sources of healthy unsaturated fats such as extra virgin olive, soybean, or canola oils.

And just published is the Harvard group’s latest report on the diet and health of tens of thousands of nurses:

Different types of dietary fats have divergent associations with total and cause-specific mortality. These findings support current dietary recommendations to replace saturated fat and trans-fat with unsaturated fats.

Even the “Is butter back?” investigators temper their conclusions:

These findings do not support a need for major emphasis in dietary guidelines on either increasing or decreasing butter consumption, in comparison to other better established dietary priorities; while also highlighting the need for additional investigation of health and metabolic effects of butter and dairy fat.

Time Magazine:  Your science writers need to do a better job of reading the literature and putting new studies in context.

Readers: consider “scientists are wrong” (and, by implication, “we are right”) to be a red flag.  Saturated fat is one nutrient in diets that contain many, and studies that examine the effects of one nutrient without considering the total diet—and calorie balance—are highly likely to require further research.   In the meantime, enjoy butter—in moderation, of course.

Jul 5 2016

The Disney-funded paper episode comes to closure (I sincerely hope)

My invited, accepted—but omitted—commentary about a study funded by Disney has at last been published by the Journal of the Association of Consumer Research.

In February, I explained how the editors had solicited this commentary, but then given it to the article’s authors to rebut, and allowed me to comment on their rebuttal.  None of this correspondence appeared when the journal published the Disney-funded article.

Could Disney’s involvement have anything to do with this omission?  The editors said no; they had just ran out of page room.

But in April, I wrote about how Stat had obtained e-mails between Disney and one of the authors indicating that the company had attempted to withdraw its study because it feared adverse publicity.  Some of the study’s authors had been associated with the Global Energy Balance Network, the group funded by Coca-Cola to promote the idea that physical activity is more important than diet in maintaining healthy weight.

When I complained about the omission of my accepted piece, the editors arranged to have it and the correspondence published in the journal’s June issue.

While the correspondence was in proof, I added a last line bringing the situation up to date: “Disney’s now exposed attempt to withdraw their paper from publication (Kaplan 2016) provides further evidence for the hazards of industry-funded research.”

Done.  Finished.  Amen.

Jul 4 2016

Happy Fourth of July!

Happy eating:

And happy thinking.  Check out Senator Elizabeth Warren’s speech on industry consolidation and concentration, including what is happening in the food industry.

Competition in America is essential to liberty in America, but the markets that have given us so much will become corrupt and die if we do not keep the spirit of competition strong. America is a country where everyone should have a fighting chance to succeed—and that happens only when we demand it.

Here’s one idea:

The Agriculture Department has a role to play in making sure that poultry farmers and produce growers aren’t held hostage to the whims of giant firms.

Jul 1 2016

Reading for the long weekend: Jennifer Grayson’s “Unlatched”

Jennifer Grayson.  Unlatched: The Evolution of Breastfeeding and the Making of a Controversy.  Harper. 2016.

I thought this book had plenty to say and said it well (and has a great cover).  I did a blurb for it:

Unlatched is a deeply engaging, highly personal, well researched, and thoughtfully balanced account of how modern society has denormalized breastfeeding.  Jennifer Grayson does not expect every mother to follow her example and breastfeed babies for three or four years.  Instead, she asks us to consider how formula feeding became the norm and how government policies perpetuate it as the norm (see especially the stunning chapter on the Women, Infants, and Children program).  She argues compellingly that our challenge as a society is to restore breastfeeding as the default for feeding babies, and to provide the support—political as well as emotional–that mothers need to breastfeed successfully.

Jun 30 2016

The FDA weighs in on GMO labeling

The Senate’s proposed GMO labeling bill gives food companies three options:

  • An on-package code that consumers can scan with a smartphone
  • A 1-800 number
  • A symbol to be developed by USDA

None of these does what Mars is already doing on M&Ms, for example—a straightforward, easy-to-read, quickly understandable statement that the product is “partially produced with genetic engineering.”

 

Now, the FDA has just produced a technical assessment of the Senate bill.

This makes it clear that the Senate has no idea what labeling rules entail.  Some examples:

  • We note that provisions to allow information regarding the GE content of food to be presented only in an electronically accessible form and not on the package label would be in tension with FDA’s statute and regulations, which require disclosures on food labels.
  • We are concerned that USDA’s regulations implementing the mandatory standard under this bill could conflict with FDA’s labeling requirements.
  • We note several points in the drafting of the bill that raise confusion.
  • It appears that the intent is to have the bill apply to all foods except those that are essentially meat, poultry, or eggs, and that the drafters may have assumed, incorrectly, that products covered by the Federal Meat Inspection Act, the Poultry Products Inspection Act, or the Egg Products Inspection Act are not covered by the FD&C Act.
  • [One section requires] the USDA regulations to “prohibit a food derived from an animal to be considered a bioengineered food solely because [of a certain fact]”. This is unclear — the language of “prohibit[ion]” and of ‘be[ing] considered”, if taken literally, would mean that an advocacy group that thought of these foods as being bioengineered would thereby have violated the USDA regulation and could be subject to sanctions.

The Senate bill is decidedly corporate-friendly.  It is decidedly not consumer-friendly.

Clearly, I’m not the only one who thinks so.

Jun 29 2016

Brexit: What it means for the food and drink industries

What Britain’s exit from the European Union (“Brexit”) means for food and agriculture is worth attention.

As The Guardian put it,

It is no coincidence that food and drink is at the heart of so much of the debate about whether we are better off in or out of the EU. Worth £80bn a year and employing 400,000 people, it is our largest manufacturing sector and a big exporter and importer. Moreover, 38% of its workers are foreign-born, placing its demand for cheap labour at the centre of arguments about immigration.

The common agriculture policy (CAP) swallows up nearly 40% of the total EU budget…Britain produces just more than half what it consumes and depends on Europe to provide more than a quarter of the rest, while the EU’s population of more than 500 million people provides the UK’s most significant export market for food.

Agrimoney, a London-based concern that reports on commodity markets began its report on Brexit’s impact with these words:

Oh dear.

Tim Lang, professor at City University London’s Centre for Food Policy, told Food Navigator:

People will pay more for food. The British people have voted to raise the food prices…Where do they think their food comes from? Planet Zog?

Bakery & Snacks is especially interested in the meaning of Brexit for the food and drink industries.

It produced a Special Edition highlighting its articles on the topic.

The UK’s decision to leave the European Union goes against the wishes of 71% of the UK food & drink industry, according to a poll by the Food and Drink Federation. William Reed Business Media publications assess the impact for individual sectors such as snacks, confectionery, dairy, bakery and feed as well as food ingredients suppliers. What will Brexit mean for the food, feed and drink industries?

And here is one more.

It’s obvious from reading all this that the effects of the Brexit decision are largely unknown. not easy to predict, but unlikely to be good.  The follow-up will be interesting to watch.

Fingers crossed that the fallout won’t be as bad as predicted.

Additions

  • Bee Wilson’s eloquent elegy for the benefits of European Union food for British palates in the New Yorker
  • Tim Lang’s expanded and referenced discussion in The Guardian
Jun 28 2016

My Time Magazine op-ed: We are still confused about calories

While I was in Israel last week, Time Magazine published an op-ed it had invited me to write.  Here it is.

Even in ‘healthy’ foods, calories can tick up fast

Nutrition professor that I am, if I could teach just one thing to the American public, it is this: Larger portions have more calories.

Please don’t laugh.

If we all understood this, the United States would not have an obesity problem. And the recent revelation that places like Chipotle and Panera serve meals with more calories than McDonald’s would surprise nobody. We would realize the former’s “health” aura blinds people. But this basic rule applies to those places, too.

We would also, strangely, thank McDonald’s for at least one thing: It limits portion sizes. It’s easy to pile on calories by asking for a little more of this, then a refill of that—without realizing that the calories surpass those in McDonald’s meals.

It’s not easy to understand calories. They are not intuitive because they’re abstract. They cannot be seen, tasted or smelled, and are extraordinarily difficult to count accurately, even for scientists. My colleague Lisa Young, author of The Portion Teller, once asked an entry-level nutrition class to guess the calories in 8-ounce and 64-ounce soft drinks. We didn’t expect students to know that an 8-ounce Coke has 100 calories—but we certainly expected them to multiply whatever they guessed by eight for the 64-ounce drink. But the average multiplier was three.

The unintuitive relationship between amounts eaten and calorie intake is one of the reasons behind public health campaigns like the new soda tax in Philadelphia, which in part aims to get people to think twice before drinking sugary beverages. No nutritionist worries about an occasional 90-calorie mini-can of soda. But many people drink sugary beverages in 12-ounce, 20-ounce or liter sizes. Bigger sizes mean more calories, and more calories means more weight unless you compensate with physical activity.

But exercising off calories takes a lot of work. That was the message of aNew York City health department campaign demonstrating the need to walk the three miles from Union Square to Brooklyn to compensate for the nearly 300 calories in a 20-ounce soft drink.

And let’s not forget that all of the calories in soft drinks come from sugars, which provide nothing but calories—no vitamins, no minerals, no fiber. They may be delicious, but they have no redeeming nutritional value. That’s why their calories get called “empty.”

Does where calories come from make any difference? Yes, but in complicated ways. Weight balance depends on calories. But managing weight—and overall health—very much depends on where those calories come from. It’s not so easy to overeat vegetables, fruits and whole grains, or relatively unprocessed foods of any kind, because these tend to be bulky and fill you up before you eat too much. You can still gain weight on these healthy foods, but it’s harder. Chipotle may have healthier calories than McDonald’s, but its calories still count.

Sugars post particular problems because they induce insulin production, but also because they make foods taste good. We eat something sweet and want more of it. We start loving sweet tastes in infancy. Breast milk is sweet; it contains a tablespoon of lactose per cup and that’s there for a reason—to make babies do the work of nursing.

But sodas are very sweet. A 12-ounce soda contains more than threetablespoons of sugars—and the calories that go with them.

It’s also very hard to separate the effects of sugars from their calories. If scientists want to know whether the calories from sugars are worse than those from any other foods, they need to feed people precisely the same number of calories from diets widely varying in their content of sugar, other carbohydrates, protein, and fat for a long enough period of time to get meaningful results. The only way to do something like this would be to keep the study subjects under lock and key for as long as it takes—inconvenient, to say the least, and very expensive.

Until the science is resolved, we can all agree that eating less sugar is a good idea for just about everyone. Sugars are nutritionally empty, are hidden in foods, and encourage overeating.

Notice that I said less, not none. Personally, I love desserts and would never want to give up sugars entirely or ask anyone else to do so. I just follow my own dietary advice: eat lots of vegetables and other relatively unprocessed “real” foods, and for everything else, pay attention to portion size. This way, an occasional sugary treat is a pleasure and nothing to worry about.

Marion Nestle is professor of nutrition, food studies, and public health at New York University and co-author of Why Calories Count. Her most recent book is Soda Politics: Taking on Big Soda (and Winning).