Will I gain weight eating 300 calories a day?

I'm not going to get into too much detail about this but I've had an eating disorder for a while and for the last 3 months I have been living on under 100 cals a day. I have to increase my calorie intake to avoid being hospitalized so here's what I have in mind: Weight watchers yohghurt: 50 cals Rice cake with tomatoandcress: 65cals 125ml fortisip nutritional drink: 150cals Will I maintain my current weight or gain weight on this new diet? I drink 2L water per day with 3 cups herbal tea (no sugar) and a black coffee Thanks