Well .. hard to say at this stage.
In general, no, 5lbs a week is not healthy. A healthy rate of loss should be around 1% of your bodyweight per week - so for you, around 2lbs a week.
BUT.
(there's always a but)
A lot of people, when they first start dieting, will lose a big chunk of weight at first due to changes in sodium levels and losing water weight. So it's possible to safely lose double or more that first week or so. The thing is to not get upset when that rate doesn't continue in subsequent weeks.
After that first rush, it should level off to around 2lbs a week.
Oh, and the other thing is that some people (like me) don't see a steady progression either. There are a lot of people who see 2lbs a week like clockwork. Then there are those who don't show any difference on the scale for a week or even two or three, and then suddenly have a "whoosh" of a large amount. It doesn't mean that they're not losing, because for a lot of us, we see the changes in our bodies and in the way our clothes fit, but the scale doesn't keep up. Our bodies are weird things ...
... and sometimes why they do what they do is a mystery.
