How bad of a diet is this for each day?

Ok, I used to eat A LOT of food. Like dinner for breakfast, unhealthy lunch, five snacks not healthy at all after school, then a huge dinner. Also snacks in school like candy because I couldn't wait for lunch. Then I got a bad cold and was nauseous so I didn't eat much. One day I had a bagel for breakfast, no lunch, and three pieces of pizza for dinner. That's it. So I was like, I can eat less then. So then for a couple days I was having a small breakfast like yogurt, or a bagel, or half a bowl of oatmeal. Than half my lunch, and no snacks in school or after, then dinner. I lost four pounds in three days. Now, I'm doing that and hula hooping (which is a good workout if u do it for an hour every day, i lost three pounds in four days doing that once) so now I'm doing them combined. I feel okay because I eat a bit more then at first like when i started getting headaches and all. But I was wondering what every ones opinion is.