Gluten free is very controversial; works for some; not for others.
Think twice about it, if you aren't celiac or gluten intolerant. There can be repercussions if not intolerant. Whole grains are an important part of a healthy diet.......
I recently read a really good article about just this -
http://www.redbookmag.com/health-wellness/losing-weight/speed-metabolism-yl
A very interesting read
Exercise can boost your metabolism.
If you really want to kick-start your metabolism, you may also try dividing your meals up into smaller portions that you eat more often throughout the day. Every time you eat, it helps your metabolism rise, so as strange as it may sound, eating frequently can help you lose weight or maintain a healthy weight.
Take care!