Can I call you Xyph? Kind of a long (but imaginative name) otherwise. Here's my 2 cents.
First, since you are not overweight, your goal should be to gain muscle. That's what "tone" is. You may actually see the scale go UP during this process, but ignore it. Muscle is heavier than fat. With more muscle, at the same weight, you will actually be smaller.
I think you are doing way too much cardio (running and the stair climber) which will burn off muscle if you are not building it quickly enough and eating to conserve it. You said you cut out fast food and have decreased your portion sizes. That's a great start, but you may be underfeeding yourself if you are not also increasing the number of meals you eat. Try to eat at least 5 - 6 meals per day, spaced about 3 hours apart. This provides your muscles with a constant flow of nutrients, prevents insulin spikes which lead to fat storage, and assure your body of having enough food.
Next, I think you are overtraining which also will burn muscle, rather than build it. Most musclebuilding programs recommend training large body parts with at least a 4 day rest, and small muscle groups with a 2-3 day rest. Are you lifting to failure? If not, you will not build muscle. Don't be afraid of getting big- women just DON'T get big, especially at your weight. For a great site on women's weight training, check the Krista Smash site,
www.stumpuous.com.
Hope this helps- check our stickies on getting started, recipes, favorite exercises, etc. And please join us on the weekly thread. As Ilene will tell you, WE LUV NEEWBIES!
Don't despair! We've got a great group here ranging from years of experience, to a few weeks. Hang in there, ask questions, and we'll do what we can to help
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