Angela --
Weight loss is complicated in some ways -- let's dissect it.
First, it's normal not to see changes regularly. How long has it been? A week? Remember that the scale weighs ALL of you: bone, skin, muscle, fat, hair AND water. You could have lost a pound of fat but be retaining a pound of water and you will not know. So, you need patience, because the scale will not always be your friend...
Second, I don't think 2.5 - 3 miles is a "little" walking -- that's excellent! You know, you should take a look at our June exercise thread -- we track the number of minutes we exercise each month and as a group are trying to reach 200,000 minutes for the year -- we could use your minutes and it would help keep you accountable!
But I got off topic there, didn't I? First, building muscle takes a while and I don't know how long you've been walking. However, walking is not necessarily going to build muscle as quickly as weight training would. I doubt it's playing much of a role.
Finally, are you tracking calories? Are you sure you're writing down everything you eat AND drink when you consider your calculations?? It can make a big difference if you take a day "off" or forget to include your daily mochachino...
You're doing great. Remember this is a MARATHON, not a sprint. Keep doing what you're doing, and try to be patient... tough as that is!
