Have you tried using a weighted vest?

Hi --

I have been looking for information about weighted vests for increasing metabolism, building muscle, and losing weight. I'm a 5 ft tall female, 57 years old. My MD says that because I'm so short -- I'll have trouble losing the rest of my weight unless I build muscle. I have a very hectic schedule-- crazy hours and traveling a lot which makes it difficult to get to a gym or even for using home equipment. I came across a number of studies that discuss the benefits of weighted vests but there's a wide range of methods for using one -- depending on gender, age, objectives. I'm wondering if anyone here has used one. If so - do you think it helped? Do you know for sure that it built up muscle? Increased metabolism? How much weight did you put in the vest? Did you wear it all day while working? Walking? Exercise? Do you know of any problems it can cause?