A few days ago, on national television, political pollster and presidential counsel Kellyanne Conway uttered a phrase destined to become an instant classic: alternative facts.

Though Ms. Conway probably wishes she hadn’t chosen those exact words, the truth is that she did us a favor by calling attention to the fact that we do live and operate in a world of “alternative facts”. That’s nowhere more true than in the field of health and nutrition. And, thanks to Ms. Conway, there’s never been a better time to talk about it than right now.

Alternative facts are the real reason everyone is confused about what’s true and not true in nutrition.

Examples of this kind of confusion and disagreement in nutrition are so numerous and so well known to readers that I don’t want to waste time reviewing them, but here’s a short refresher. We disagree on fat, on calories, on diets, on vegetarianism, on butter, on coffee, on statin drugs, on cholesterol, on the best way to lose weight, on low-carb diets, on the dangers of meat– you name it and there’s a serious scientific dispute about it, and probably some really nasty feelings to boot.

It’s about time that we all understood why,

The best way to illustrate what I’m about to say is with a completely non-partisan example of an industry that everyone who has ever traveled has feelings about—the airlines.

If you’re a traveler, it’s important to you to know the “facts” about the airlines you fly, right? How often are they late? How often do they crash? Do they lose your baggage? How’s their customer service? And which one has the best prices?

You know, facts.

Well, it turns out there is data on every single one of those metrics, just like there is data on food, medicine, supplements, statin drugs, the Suzuki violin method, interval training, and virtually anything else you can think of where things can be measured. Which of these facts you choose to talk about depends completely on what your agenda is.

Back to the airlines.

If you’re Virgin Airlines, your marketing department is going to make hay out of the fact that Virgin is ranked the best airline to avoid mishandled baggage, and right behind Delta if you want to avoid involuntary bumping. You will probably not mention the fact that Virgin is one of the worst when it comes to “extreme delays”.

If you’re Delta, on the other hand, you will definitely mention that you are the airline with the least number of cancelled flights and the least amount of involuntary bumping. You will leave out the fact that you’re one of the absolute worst for 2-hour tarmac delays. (You won’t say it’s not true—you just won’t mention it.)

If you’re selling alcohol, you’ll probably talk about how moderate drinking lowers the risk for heart disease, and leave out the fact that drinking alcohol increases the risk of breast cancer. If you manufacture statin drugs, you’ll make a very big deal about how statin drug users have less heart attacks while burying the fact that they have more cancer and diabetes.

If you’re a real estate agent selling a house, you’re going to talk up the 3,000 square feet of space and the gorgeous new kitchen, while minimizing the fact that it’s in a high-crime area and doesn’t have a view.

And if you’re the sugar industry, you’ll spend a lot of marketing dollars to call attention to how little Americans exercise, all to take focus away from the role of sugar in metabolic misery.

Just pick the facts you like and ignore the inconvenient ones.

The people who are selling you Delta Airlines, alcohol, sugar, tobacco, statin drugs or the beautiful house in the shitty neighborhood are not lying, at least not directly. They’re just using a tried-and-true marketing technique called cherry picking the evidence. Big Pharma has been doing it for… well, forever.

Welcome to the world of alternative facts.

We’ve come to expect the use of alternative facts in politics. We need to start realizing that they’re also used to make arguments in nutrition and medicine. And whether it’s politics or nutrition, those choosing which facts to present (and which to ignore) almost always have an agenda to advance.

See, everyone likes to say “facts are facts” but the truth is that facts are neutral, impartial, bloodless numbers—and there are zillions of them. They don’t really acquire meaning until someone chooses the “important” ones, and then strings them together to craft an argument.

So the next time someone argues that vegetarians are healthier than meat eaters, or statin drugs save lives, or high-fat diets make you sick and obese, or that raw food is the healthiest way to eat, or that obesity is only about calories and exercise, don’t call them liars. The truth is, there are enough “facts” hanging around to make a case for just about anything.

Instead, ask yourself what facts are being left out.

Very often, the facts they don’t tell you are the most important ones of all.