Are Water Diets Healthy?

I tried a water diet for 2 weeks and lost 20 pounds. I started at 202, and now I'm 179. I started eating again, but nothing after 6pm and I only drink water. I also only eat one meal a day. Celery, Cucumbers, and sometimes baked chicken or chicken salad with mayo. I started hearing that when I start eating I'll gain all of my weight back, and I've gained 3 pounds within just 2 days of eating >___< How do I get rid of this weight and keep it off?