In a world of ever-changing advice, here's how to make sense of nutrition news.
Credit: Illustration: Sarah Wilkins

File this under things we wish were true: Eating chocolate every day will help you lose weight. That was the conclusion of a 2015 study titled "Chocolate with High Cocoa Content as a Weight Loss Accelerator." Unfortunately, the study was pseudoscientific hooey, the work of journalist John Bohannon, PhD, and colleagues, concocted to show just how easy it is to publish bad science promising good nutrition news.

Bohannon is passionate about science and impatient with researchers' and health care providers' failure to make clear to the public one truth: Nutrition science is not simple. "It seems like it should be easy because we all relate to it—we all eat. But nutrition is more complicated than astrophysics, and we know far less about it," he says.

If a blog or article is offering advice based on research, "look up the research, and read the actual study," advises Alisha Farris, PhD, a childhood obesity extension specialist at Virginia Tech. "Many times findings are hyped up to get attention."

So how does your average I'm-just-trying-to-eat-right person sort the legitimate nutritional news from the let's-all-eat-candy nonsense that we all come across regularly? Here are three things to look for in a study.

"The best studies will be in humans," says Walter Willett, MD, MPH, DrPH, author and chair of the department of nutrition at Harvard's T.H. Chan School of Public Health. Make that lots of humans. Thousands are good; tens of thousands even better. "A few people don't mean very much, while a large, varied population is more likely to be reliable," says Willett.

Willett also notes that the studies should follow their subjects for long periods. "From a scientific standpoint, short-term studies in humans can provide us with some interesting leads, but they should not be the basis for making decisions about diet," he says. How long is long enough? "In general, weight loss studies should last a minimum of a year," he says. That's the bare minimum. Willett and his fellow researchers are collecting and analyzing data from studies that have been following groups for decades.

To the more subjects/more time rule, add more studies. "It's so important that we don't depend on one study," Willett says. "Rarely would a single study be enough to make conclusions upon which to base your diet. An important part of the scientific process is making sure that results can be replicated, and that multiple studies reach the same conclusions," Willett explains. "When a finding shows up repeatedly, it's more likely to be true."

Now that you know what falsehoods to look out for, what truths should you seek when thinking about your own weight loss goals?

"Learn to be happier with your body. That's solid advice. That's something we should all get behind," says Bohannon.