I’ve seen so many quick at-home workouts for abs, or Instagram tutorials on the best ab workouts. If you’ve ever tried any of these 30-day challenges chances are you’ve realized that they don’t quite get the job done.

To many people, having abs is the sign of being fit, but there are a lot of reasons why it isn’t a judge of how in-shape someone actually is, and certainly not how healthy they are. In fact, it doesn’t matter how much you workout your core sometimes, because there is more to having a visible six-pack than building up the muscle.

Extra skin can’t be worked away

I’ve seen too many people really struggle to six results in their core, and the disappointment they feel is evident. There is one factor that many people who have kids or have lost weight don’t take into account: loose skin. The extra skin from a pregnancy or weight loss can’t just be worked away like fat can, and it can be pretty discouraging when you are working hard on your workout routine but can’t seem to push past that last little obstacle.

What makes this even worse is all of the Instagram influencers who seem to bounce back so well from pregnancy and extreme weight loss — but there is one tiny little thing they aren’t telling you. While some people do naturally have more elastic skin, and hydration, diet, and age can affect how well their skin ‘snaps’ back, it isn’t uncommon for the extra skin to need to be removed (unfortunately, this sometimes requires a small amount of surgery).

Abs are made in the kitchen

You may have heard this phrase before, but it couldn’t be more true. Having visible abs is just as much about maintaining a low body fat percentage as it is working out. Just because you can’t actually see the progress you are making with your core muscles doesn’t mean you aren’t making progress.

It also doesn’t mean that you have a high body fat percentage, either, in fact, most people’s average body fat percentage is too high for you to see their abs, but it doesn’t mean that they are at an unhealthy weight.

They have to be maintained

Sure, you could get abs in 30 days like some workout plans claim if you are already into fitness and have a low body fat percentage. But, even if you could, you have to be as vigilant about keeping them as you are getting them. Like other muscles in your body, your abdominal muscles must be consistently worked, otherwise they will atrophy.