I started out at 340 and my personal trainer put me on 1800 calories a day. Most days I'm pretty close on target, never going under 1600 and rarely ever going over 1800. For five months I lost an average of 3.6 pounds per week. The past month it has slowed down slightly, but I'm still losing. From the little details you gave us I think you are doing ok. I wouldn't recommend going under 1600. You also want to be sure that you are eating a healthy balance of those calories. I eat lots of fruits, veggies, whole grains, lean proteins, yogurt, cottage cheese, healthy fats. As much as possible I avoid processed food. I drink water, crystal light, green tea and the occasional black tea. I mostly avoid caffeine. I should also mention that I do exercise 7 days a week, 3 of those days involve strength training.
Looks like you are off to a good start. This is a great place for support, encouragement and information! It's a good part of a healthy lifestyle!
