Q: Could I safely lose 3 pounds/week?

A: It's not going to endanger your health, but it's faster than I recommend for a sustained fat loss. If you lose this fast, unless you're very overweight, you will be certainly losing significant amount of muscle in the process which will eventually lower your metabolism, halt the weight loss, and make yourself very vulnerable to new fat accumulation. I strongly recommend staying in 1-2 pound/week weight loss range for most people, the slower the better.