If you weigh 173 pounds and are 5 foot 6 inches how much weight do you need to lose?

Healthy weight for a person who is 5'6'' tall is roughly between about 125-150 lbs. The range is due to reasons like being a man or a woman, health conditions, famlily history, amount of muscle, ect. A good goal to shoot for (starting from about 170) would be about 25 to 30 lbs. That would place you down at around 140 or so.