Im a female 18 years old 54 and in the past 4 months i lost weight 135 to 107 and i want to gain some back because i went too far i wanted to know if my weight is deadly and must be treated now or can i gain weight back slowly at 2500cal a day?

Some basics: You maintain a steady weight when you match calories ingested with your daily calories burned. The burn rate depends on basic need, muscular & intellectual work. A pound equates to ~3000 calories. If you consume 500 calories more than your base need you would expect to gain a pound every 6 days.You may want to consult a clinical nutritionist to help with this goal.