You might think that a certain weight means a certain metabolism. However it makes a HUGE difference if that weight is mostly fat - or mostly muscle.
If you have a pound of fat, its maintenance burns about 2 calories each day. So for example if you have 20 pounds of fat in your legs and thighs, that would be 40 calories a day it would burn by being there.
However, let's say that you go walking each day and turn those 20 pounds of fat into 20 pounds of muscle. Sure, you weight the same. However, your legs look MUCH better - they look toned and smooth. Plus, muscle burns a whopping 35 calories a pound. So that exact same 20 pounds of weight, because it is muscle, is now burning 700 calories every day!! That is a HUGE difference. Note that the 35 calories isn't even a "high estimate". Some people estimate that muscles can burn up to 50 calories per pound per day! I just read a nutrition book that pegged the value even higher, at a full 75 calories a day for a pound of muscle.
Now, think about it in this way. It takes 3500 calories of exercise in order to completely dissolve a pound of fat. So if you had 20 pounds of muscle, then that muscle alone would be burning a pound of fat every 5 days by being there. That would be without you exercising at all - just hanging out and sleeping.
Let's also note that a pound of muscle is not as "big" as a pound of fat. Fat is fluffy. So if you turn 20 pounds of fat into 20 pounds of muscle, the muscle will be much slimmer and trimmer. Your clothing sizes will definitely shrink.
Many women worry about becoming muscle-bound - about turning into Arnie from the Terminator. Never fear. It takes an incredible amount of work and training for a woman to look like that. The vast majority of women who work out daily end up looking lean and trim. Their muscles are naturally smooth and tight. The muscle helps them fit into clothes better, run up stairs, play with their children, stay balanced on icy sidewalks and carry their groceries. These are activities that hopefully all of us want to participate in.
Find even small ways each day to stay active and to build up your healthy muscle mass!