You’ve no doubt seen countless health and fitness articles or videos. In these, it’s really common to see things like “sugar causes obesity” or “letting your knees go over your toes is terrible for your knees” or countless other black and white statements. And the irony of it is that about a decade ago, the exact opposite was being preached with the same fervor. In other news, we have always been at war with Oceania and Eurasia is our ally. So what’s going on here? Why do we keep swinging from one extreme stance to the next?

The short answer, is that humans like simple stories and black and white answers. There are a couple of reasons for this. The first is that it’s efficient. Going over all of the nuances of something requires a lot of thinking, which requires a lot of energy. In the old days, when people used their feet to power their cars and dinosaurs to work in quarries, food was scarce and required a decent amount of work to get. The last thing we needed was to spend energy where it didn’t absolutely need to be spent, like thinking about the complexity of human metabolism. Problems were things like “there’s a tiger, don’t get eaten.” The decisions were pretty limited and the consequences pretty obvious. You can either run away or stick around. If you stuck around, you could either fight or get eaten. Yes, there has always been human drama driving us as well. But the bulk of the decisions we had to make regarding the rest of the environment weren’t exactly nuanced.

Fast forward to the present day and we’re still working with hardware built to fit a prehistoric environment. The problem is that we need to make decisions for which the quick and dirty, black and white approach isn’t matched. Figuring out your retirement plan is a lot more complicated than finding firewood. Choosing foods out of the abundance available to bring you the best long-term health and wellness is nowhere near as simple as seeing the food available while you’re starving and then eating it immediately.

So how does this play out in our modern fitness environment? Well, for one thing, you end up with a lot of black and white claims. “Fat is bad!” “Squatting with knees over toes hurts your knees!” “High reps burn fat!” “Cardio destroys muscle!” These claims get made and the average person sees them and implements them. Then, when things don’t go as expected, people either get frustrated and give up or the opposite claim becomes popular. “Fat isn’t bad after all. It’s carbs that are evil incarnate!” “Your knees should go as far as possible over your toes when you squat!” “High reps are a waste of time. Go heavy for low reps always!” “Cardio is the one thing you’re not doing that you need to!” I have no doubt that in a decade we’ll hear that fat is evil again or that eggs are bad for you or that cardio is sent from hell. The pendulum swings back and forth eternally, it seems.

So what can you do about all this? Well, you’ve already started educating yourself. The most important thing to remember is that there’s context for everything and simple binaries, while very comfortable, aren’t the whole story. The fact is that you’ll have to embrace the inherent messiness that comes with understanding anything on a more than surface level. Kind of like how when you realize that every human is messy because they all have their virtues and flaws and inconsistencies, figuring out all this health stuff is the same.

Carbs are bad when you’re eating way too much food and diabetic (mainly because they’re too much food, not because they’re carbs.) Squatting with your knees going over your toes is fine as long as your heels are flat on the ground and you’re pushing through the whole foot and it doesn’t cause knee pain. Being more active burns more calories, but fat loss only happens when you’re in a caloric deficit (eating fewer calories than you burn.) Having a certain amount of cardio is good for your heart and general endurance.

All these things will go back and forth for a very long time. In my own life, I remember a time when intermittent fasting was called the warrior diet, keto was known as the Atkins diet, very high reps was the way to train, and cardio needed to be done all the time. Two out of those four are already very popular now and I have no doubt the other two will be too. And a decade later, the the opposite will be true. So it goes.