By now, you’ve probably heard all about the keto diet, one of the latest nutrition trends promising quick weight loss and a slew of other positive side effects. It’s a super low-carb, high-fat diet that’s been shown to help people lose weight thanks to a little process called ketosis—a term you’ve likely seen if you’ve Googled the keto diet. But do you know what ketosis actually is? Here, we break it down for you.

What is Ketosis, Anyway?

Put simply, ketosis is a process your body goes through when it doesn’t have enough glucose (sugar) to use for energy, according to Medical News Today. Instead, it starts to burn fat for energy, and ketones start to build up in your blood. Ketones are the acids your body uses for fuel while you’re in ketosis. The big takeaway here is that the extremely low carb intake forces your body to burn its fat stores for energy instead of the sugars it would use if it were breaking down carbs.

Is Ketosis Safe?

If the idea of purposely making your blood more acidic doesn’t sit right with you, we don’t blame you, but ketosis is safe as long as you’re healthy. If you’re concerned about it, you can monitor your ketones while you’re following the keto diet. Monitoring them will make it easy to find out whether you’re actually in ketosis, but it’s also a good idea because it’s possible to take it too far, particularly for people with type 1 diabetes.

It’s a rare occurrence, but extremely high levels of ketones can lead to ketoacidosis, which is when your blood itself turns acidic. It’s a potentially deadly condition that can happen to diabetics who don’t take enough insulin and people who are starving, for example. But a non-diabetic person on the keto diet shouldn’t have ketone levels anywhere near high enough to cause ketoacidosis.

For more on the keto diet, check out this comprehensive guide to going ketogenic.