Hello Jess: You don't say how tall you are. So it's difficult to say if your weight is a problem. This is easy enough to check on most health-related websites. You can plug in your weight & height & it will tell you if you're too thin, within normal range, or overweight. Eating & then not eating for several days isn't a healthy practice. Your body needs fuel on a regular basis. On the other hand, if you're otherwise healthy, it's not going to harm you seriously either as long as you don't overdo it.

The danger comes in when you begin to starve yourself trying to achieve some imaginary degree of thinness that you never reach. This can become a compulsion that can be difficult to break.

As things stand now, you may, or may not have an eating disorder. I'm not qualified to say. But, given how serious an eating disorder can be, I would recommend that you get assessed for this &, if necessary undergo some treatment, or perhaps just one-to-one therapy, in order to ensure that what you're doing now doesn't turn into a full-blown eating disorder. My best wishes to you!