Suggest An Effective Diet Pill To Lose Weight

Do certain diet pills work? I m relatively active at least 4 days a week and I ve started eating very health and my portion sizes are a lot smaller than they use to be but now I ve stopped losing weight like I was a few weeks ago. I dropped 13 lbs in about 2 or 3 weeks and now I m just staying at my current weight. Should I see a nutritionist for advice.