You do not always need to respond, but sometimes a well-placed comment can clear the air or help others reconsider their attitudes. Yeah, I'm healthier. It's the way my body works. Everyone has a different metabolism.
People have different genetic backgrounds.
My body and brain need carbohydrates for energy. Because I'm healthy and don't deprive myself of foods my body needs. Low fat is fine, but zero fat isn't healthy. Our bodies need dietary fat to absorb vitamins and produce hormones. Thanks, but I prefer to stay sane.