Your healthy body weight is that weight at which you are strong and healthy. The slower you lose weight, the more likely you are losing fat and not muscle. If you have a high level of body fat, or you have never been able to successfully lose fat, you should consider trying a program that not only focuses on dieting, but also includes adequate cardiovascular activity and weight training. The best way to get ripped and maintain as much muscle as you can is to diet slowly. Losing a little or a lot of fat involves pretty much the same concept - adequate nutrition coupled with cardiovascular exercise and weight training.
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More info and a built-in Healthy Weight Calculator