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Saturday, November 29, 2014

The paleolithic diet and the very provable links to our past

As the evidence in support of the Paleolithic diet continues to pile up, it's becoming more and more difficult for popular health writers and government public health agencies to ignore it. Some have gracefully conceded that they may have been wrong, while others are stubbornly doubling down on their criticisms of the diet.

Writing at The Conversation, evolutionary biologist Darren Curnoe typifies the second approach. He argues that the Paleo diet is a " largely impossible dream based on a set of fallacies about our ancestors," even positing that the diet could be harmful. His arguments are similar to Marlene Zuk's criticisms of the Paleo diet, and consequently Curnoe is wrong for the same reasons she is: he ignores evidence that doesn't fit his argument and misstates what proponents of the diet actually recommend.

The first key point to make is that the Paleo diet works. Regardless of the more abstract issues in play, like whether or not human evolution has stopped, the fact remains that people who go on some variant of the Paleo diet lose weight and improve their health, often dramatically.

Several studies back up this conclusion, all curiously absent from The Conversation piece. One 2007 study compared the Paleo diet to the Mediterranean diet and found that the former better enabled men with heart disease and type 2 diabetes to control their blood sugar. Both groups lost weight, but the Paleo group in the study naturally ate fewer calories and saw greater reductions in waist circumference. Every patient in the Paleo group was also able to bring his blood sugar down to normal levels.

Another study from 2009 similarly found that "a Paleolithic diet improved glycemic control and several cardiovascular risk factors compared to a Diabetes diet in patients with type 2 diabetes." A study of healthy but obese women found comparable results as well: the patients lost weight, reduced their liver fat; lowered their blood pressure, cholesterol and fasting blood sugar.

There are other studies that could be discussed, but you get the point. Compared to the diets deemed acceptable by the medical establishment, the Paleo diet does a better job of improving every marker for metabolic health we currently measure. Moreover, it's helping people who are most at risk for harm-- fat people, diabetics and heart disease patients.

The foundation of Curnoe's argument is that the link between a healthy diet and our Paleolithic ancestors is dubious. He cites an International Journal of Obesity article in support of this point, which argued that scientists have a difficult time determining how our biology influences our propensity to gain weight, though they know it exerts some influence. From this information, Curnoe says that the Paleo diet is based on "assumptions [that] are difficult to test or even outright wrong." But given this admitted ignorance of how evolution influences obesity, I'm curious how Curnoe or any other critic can so confidently attack the Paleo diet. If the evidence is too limited to draw a conclusion, why is Curnoe drawing a conclusion?

But there is quite a bit of evidence to draw from, and none of it offers Curnoe much help. Though human evolution hasn't stopped, research indicates that most of the human genome is composed of genes selected during the Paleolithic Era. In fact, "Many scientists ... expected that surveys of our genomes would reveal considerable evidence of novel genetic mutations that have recently spread quickly throughout different populations by natural selection... [but] most of the detectable natural selection appears to have occurred at a far slower pace than researchers had envisioned," according to this 2010 piece in Scientific American.

Such a slow pace of natural selection would explain the conclusion of this 2011 paper "that modern Homo sapiens are still adapted to an ancestral environment ... hunter–gatherers ... exhibit superior health markers, body composition, and physical fitness compared with industrialized populations." If you doubt the diseases of civilization hypothesis, follow the link and checkout the copious footnotes listed in support of the argument. Far from dubious, the link between a healthy diet and our evolutionary history has been well established.

Parenthetically, I wonder if Curnoe ever stopped and thought about the modern examples of people successfully following the Paleo diet. These individuals are living by advice he says is unsubstantiated and dangerous, yet they're getting slimmer and healthier. Such outcomes would seem to lend support to the idea that humans are indeed mismatched with their modern environment.

Curnoe also argues that it's a misnomer to describe diet and exercise habits from the Paleolithic as a single lifestyle because studies have found "a great deal of variation in the diet and behaviour" from this period. That's true to an extent, but Curnoe's statement overlooks the similarities running through the diets of all these different Paleolithic populations, particularly foods that would not have been in any of their diets. Table 4 from the 2011 paper in Research Reports in Clinical Cardiology lists items like isolated sugar and oils, cereal grains, alcohol and dairy. The modern western diet contains all of these foods in excess. Combined with too little sun exposure, lack of sleep and limited physical activity, this is a recipe for a very unhealthy population.

 I want to reiterate that a healthier society is what we're after. The questions posed by anthropologists and evolutionary biologists are secondary to this goal, and we've found a diet that helps us reach it. So in summary, I'll say the same thing to Curnoe that I said in response to Zuk's book last year: "We have evidence from thousands of people who have documented their experiences on a Paleo diet, and the results are remarkable. People from all walks of life have lost weight, beaten eating disorders, reversed diabetes and heart disease — and all by living a lifestyle that Zuk says is 'misguided nostalgia.'" Why anyone would attempt to obscure or ignore this fact is beyond me.






Monday, November 24, 2014

The FDA mandates calorie counts on menus. In other news, world still getting fatter

I eat fast food perhaps once every three months. When I do, I break all my usual health rules. I skip my workout, order the biggest portions of everything and then happily enjoy every bite of my heart-stopping meal. One thing I never do on these rare cheat days, however, is fret about how many calories I consume.

But the federal government knows better than I do, and will soon mandate that chain restaurants, vending machines, grocery stores, pizza places and even movie theaters display calorie information on their menus.

This calorie count proposal, like the similar state and city level proposals before it, will fail. Consumers know before they walk into the restaurant that they're about to eat junk food, and there is no reason to think that helpful suggestions from the FDA will make them slimmer.

Depending on which study you read, somewhere between 30 and 60 percent of Americans pay attention to calorie counts in restaurants and grocery stores. There's really no way to know if those figures are accurate, since all the researchers can do is ask people if they look at the calorie counts. But keeping in mind that survey studies like these are usually inaccurate, especially because of self-report bias, I'm willing to bet that people who participate in these studies are lying. Moreover, even if consumers are utilizing calorie counts, they're not eating less, according to researchers who looked at what they actually purchased before and after the calorie counts were implemented.

So we don't have the foggiest idea of how many people are utilizing the calorie information on menus, and nobody's eating any less while we try to answer that question. But even if those two conditions were met, we still wouldn't make a dent in the obesity statistics, because the problem is more complex than that.

A big salad and a small candy bar may contain the same number of calories, but one is much healthier than the other. The nutrients in the food we eat are just as important as the amount of food we eat when it comes to maintaining a healthy weight; the studies are very clear about this now. You'd have to be an idiot to believe otherwise. And since we're talking about a federal initiative, that's probably a fitting description for the people who are pushing to add calorie counts to menus in movie theaters.

But the health mullahs have research, too. They're particularly fond of one study conducted in Seattle which found that some restaurants began using lower-calorie ingredients after implementing calorie counts. The declines, though, were very modest and the study only looked at restaurants in one city. Generalizing the results to the entire country, as the FDA is doing, is inappropriate.

When we do look at the data on obesity around the world, we find that countries tend to get fatter as they get wealthier. The wealthiest countries are the ones with the best health care and education and the most developed health bureaucracies, because they can afford them. If the issue was educating people about healthy eating, America would be the slimmest, sexiest country in the world. Clearly the issue isn't lack of access to information. We all know that cheetos make us fat.

There's really only two ways consumers' eating habits are going to change. We either have to pay them to eat healthier foods, as political scientist Eric Oliver has pointed out, or we have to force them to change their behavior. That can only be done by restricting people's choices--through heavy taxes, product bans and tighter regulations on advertising. The latter option is not tenable just yet on the federal level, but it's probably coming soon, as the calorie count initiative suggests.

Despite their protests that they just want people to make informed choices, public health advocates are not above forcing people to change. These issues always start out as discussions about how we get consumers to eat healthier, drink less or quit smoking, and they almost always end as political campaigns to restrict personal freedom. It's never just about the science.

Saturday, November 22, 2014

Shirtgate and the myth of a sexist conspiracy in science

Two weeks ago, a scientist with the European Space Agency wore a tacky shirt during an interview about the Rosetta Project. That seems like an extraordinarily uninteresting news story, but the internet was awfully displeased with Dr. Matt Taylor's supposedly sexist wardrobe, taking his shirt as a sign that women in science still face all sorts of discrimination.

There were a lot of angry tweets and anecdotes about sexism in science, but curiously missing from the uproar was any discussion of the evidence. Why, you may be inclined to ask, did Taylor's shirt receive so much attention? Because there isn't any evidence of sexism in science. In fact, contrary to the claim that science is a refuge for antiquated beliefs about women, it's actually a terrific example of how far our society has gone to eradicate discrimination.

Sexism was entrenched in our scientific institutions until just a few decades ago, and we probably haven't eliminated the problem in such a short amount of time, or so the argument goes. But there's some flaws in this assertion, and the way we do science today reveals the most obvious one.

The majority of scientific research is funded by the federal government, performed at major universities and then promoted by the mainstream media. Judging by the Obama administration's campaign to get more women into the sciences, the government is no friend to sexism. And since the majority of university students today are women, it's fair to say that our schools don't take kindly to sexism, either. The media's coverage of shirtgate similarly illustrates that anyone who openly discriminates against women will be ostracized.

In other words, the institutions that finance, produce and promote science in America, the institutions with the influence to keep women out of the sciences have no interest in such a conspiracy. They have, in fact, voiced their support for women who want to enter STEM fields.

This should end the argument, at least for everyone without an ax to grind. You can't have institutionalized sexism if the relevant institutions are opposed to it. Of course, the ax grinders among us could object to this argument by suggesting that sexism has slipped through the cracks at these institutions. Though discrimination in the sciences has been reduced, there's still an "atmosphere of denigration" surrounding science, as astronomer Phil Plait argued in a column at Slate this week.

Plait's argument is weak, though. He cites some statistics and a few anecdotes from his female colleagues, but he ignores everything that doesn't fit his conclusion. For example, he fails to mention that women earn the majority of PhDs, across all fields. He also skipped over a 2011 study which found that women don't face institutional discrimination when competing for grants and jobs and trying to publish their research. Perhaps most importantly, he didn't mention that girls are now performing just as well as their male counterparts in high school math, which means they're capable of going into math intensive fields like chemistry and physics, should they choose to.

Nonetheless, there are still more men in the hard sciences, so if not discrimination, what explains the disparity? Many feminists will protest this claim, but men and women are very different creatures; the biological evidence for this is overwhelming. I humbly suggest that these differences between the sexes influence everything about our lives, including our divergent career choices.

With all of this information in mind, choice as an alternative explanation makes plenty of sense. Women are the majority on college and university campuses around the country. They're just as intelligent as men; their SAT scores and graduate degrees are evidence of that. Moreover, they're studying and working in an environment that's friendly to their ambitions, thanks to a dramatic shift in the cultural and legal landscape that's taken place over the last several decades. Discrimination can't possibly be the best explanation of these facts.

Women have rightly been given the opportunity to pursue the careers they want; they're just not making the same choices men are making. That's okay. Now, let's go find another problem to solve. There's plenty to choose from.