There’s a lot of conflicting nutrition information out there. What should you believe?
There’s a lot of conflicting nutrition information out there. What should you believe?
Nutrition Diva is hosted by Monica Reinagel. A transcript is available at Simplecast.
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The other day, I was going back and forth with some of my Twitter friends about the issue of whether eating more frequently keeps your metabolism burning at a higher rate. You might recall that I did a show on this not too long ago. As I discussed in episode #31, the evidence simply doesn’t support this widely-held notion.
Nonetheless, one of my friends says he’s still swayed by some compelling arguments he’s heard to the contrary. And someone else who’d been following our exchange chimed in that it’s sometimes very hard to know whom to believe. And it’s true, there is a lot of conflicting information out there—some of it very persuasive and convincing. How do you know whom to trust?
Of course, no one is going to be right 100% of the time. We all make mistakes. And there’s the added complication that what we know--or think we know--about health and nutrition is constantly evolving. As we get more information and do more research, we sometimes have to revise our positions.
A good scientist is eager to abandon any position that’s been proven false, no matter how strongly he might have held or argued that position previously. Unfortunately, it can be hard for individuals--and even harder for institutions and government agencies--to cut bait on outdated positions that they’ve invested years and careers into promoting.
For example, as I mentioned in a recent newsletter, it’s been clear for a while now that eating foods containing cholesterol, such as eggs or shrimp, does not increase your blood cholesterol levels, as we once thought. But the American Heart Association is having trouble letting this one go and is still advising people to limit their dietary cholesterol.
But, I digress. The question is how do you evaluate the nutrition information you come across in books, magazines, and on the Internet? I’ve been thinking a lot about this since our exchange on Twitter and I’ve come up with a few tips that you can use to gauge the reliability of the information and the sources you come across.
First, what is the educational background and credentials of your source? There are a lot of self-taught nutrition experts out there. I know, because I used to be one.
Remember, I originally studied music and started my career as a professional opera singer. Like most young opera singers, I supported myself with various day jobs and one year, I got a job with a publishing company in the research department of their health division.
It was a great job; I loved reading about health and nutrition and already knew a fair amount about it. Before long, I was writing short features and fillers for the publications. Within a few years, I had a pretty solid career going as a freelance health writer. I felt like quite the expert.
Until I went back to school to earn a graduate degree in nutrition. That’s when I realized the difference between someone who learns about health and nutrition by reading popular books and browsing the Internet and someone who has had a formal education in the subject.
I’m not saying that people with initials after their names are always right or that you need to have an advanced degree to know what you’re talking about. But it helps. All that anatomy, physiology, biochemistry, statistics, and research method they make you slog through really gives you an edge when it comes to spotting inconsistencies, fallacies, and errors in very scientific-sounding explanations.
This background also helps you put the facts into perspective. Many nutrition myths have their basis in something that’s actually true, but the facts have been misconstrued, misinterpreted, or simply misapplied. Something can be true without being particularly meaningful or relevant.
For example, it’s true that caffeine is a diuretic, meaning that it increases your urine output. However, it’s not true that coffee is dehydrating, because it contains more water than the caffeine causes you to lose. It’s also true that you’ll burn more fat while exercising on an empty stomach but that won’t help you lose more body fat in the long term. (To understand why, see episode 45.)
Statistics are notoriously slippery. If I told you that using a random number selector instead of playing your mother’s birthday would make you a hundred times more likely to win the lottery you might be pretty excited, unless I also told you that you’d still be much more likely to be hit by lightening—twice—than you are to win the lottery. A lot of nutrition advice is based on exactly these sorts of statistics.
A well-referenced argument is always more credible than one with no backup. But don’t be overly dazzled by footnotes. I’ve seen nutrition articles online studded with tiny numbers after every sentence and pages upon pages of references at the end. But a closer look reveals that most of the references are websites, magazine articles, and other sources that present the same arguments, also without citing any solid evidence. That is the equivalent of “hearsay” in a court of law, and we all know that hearsay is not good evidence.
I’ve also checked references and I found that the cited materials didn’t actually support the argument the author was making. It makes me wonder whether the author actually read them.
It gets very circular. There is a lot of nutrition lore that’s never been proven or even tested in any serious way— such as the idea that eating protein and carbs at the same meal somehow impairs your ability to digest them. It’s simply been repeated over and over again—until many believe it to be true.
Even worse, there is nutrition lore that’s been definitely disproven—like the idea that chocolate aggravates acne or milk increases phlegm production. And yet it continues to be repeated (and believed). I’m constantly doing shows on stuff like this and you can find them all in the episode archives at nutritiondiva.quickanddirtytips.com.
If you’re looking for a reliable source of nutrition information, you want someone who is willing to do their own primary research, with an open mind. That means checking the scientific literature directly, and reporting all that they find there. It’s not fair to cite the one study that supports their view and not mention the 75 that refute it. They don’t need to detail all 76 studies, but they do need to give an accurate representation of what’s out there.
In short, you want someone who will give you the facts, tell you where they got the facts, and then be very clear when they start giving you their opinion and interpretation of those facts.
Basing treatment on the latest scientific evidence, rather than personal experience, hunches, or conventional wisdom, is called evidence-based medicine and it’s the gold-standard for the practice of nutrition, as well.
But here’s the thing: Individual results may vary. Evidence-based medicine is grounded in statistics. The more data points we’ve gathered, the more confidently we feel we can predict what will happen. But we can’t guarantee something that was true for 99% of the population will be true for you.
And that’s why even though research shows that eating every three hours is statistically unlikely to affect your metabolic rate, you still might find that eating more often makes it easier for you to lose weight. You could be the statistical anomaly. Or, more likely, it might be that eating every three hours doesn’t affect your metabolism at all but perhaps helps you control your appetite better.
If you’ve already found what works for you, then all the statistics in the world don’t matter. If you haven’t, it makes sense to start with the approach most likely to produce good results. And that’s why I encourage you to look beyond compelling narratives, pseudo-scientific jargon, and personal testimonials when shopping for health information and look for the type of things I’ve mentioned here.
This is Monica Reinagel, the Nutrition Diva, doing my best to get it mostly right most of the time. If you have a comment, question, or suggestion for a future show topic, post it on the Nutrition Diva Facebook Page or find me on Twitter.
Have a great day and eat something good for me!