Women tend to hold fat in certain areas - especially the thighs. You'll be able to tone muscle and lose fat in your arms more easily. Thin women with little body fat elsewhere on their body can retain fat in their thighs - it's just the way women are built. Thighs are designed to be fat storage units, so it can be difficult to burn the fat that is there - it will take a healthy diet and a lot of exercise.
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