I went on a several-month-long binge after restricting heavily a few years ago and went from my then lowest weight of BMI 18.4 to BMI 25.6. It certainly isn't healthy and I would suggest making sure you eat three dense, fibre-rich meals every day (such as bran flakes for breakfast, brown rice for lunch, wholemeal pasta for evening meal) so that if you do binge you are less likely to binge as much.