A nutritionist needs no credentials; however Registered Dietitians receive extensive training in food science and nutrition, and must pass an exam given by the American Dietetic Association. A Certified Dietitian-Nutritionist is certified by the State of New York .  

No. Some carbohydrates, such as whole grain breads and cereals, or fruits and vegetables, which are high in fiber, are better for us. This is because they don’t cause blood glucose levels to rise rapidly. Refined carbohydrates, like white flour, pasta and sweets cause a rapid rise in glucose levels resulting in a rise in insulin secretion, which can lead to increased fat storage.  

Unfortunately, no. Many low-fat foods are high in sugar and therefore high in calories. You are usually better off sticking with the “regular” product and watching portion sizes.