Grating and rinsing the potato will only remove some starch from the cut surfaces. Using warm or cold water in the rinse will not make any appreciable difference. However, multiple rinses or soaking will help reduce the starchiness, if so desired. Simply rinse until the water is relatively clear within the basin or tub. Protein will remain intact in the potato despite any rinsing. By leaving the skin on you will however, retain extra fiber as the skin has slightly extra fiber within. If you’re concerned about calories with potatoes you shouldn’t be! Potatoes are naturally low in calories (110 calories per 5.3 oz serving), with zero fat and are loaded with vitamins and minerals. Here’s a link on our website that illustrates all the great attributes of Idaho Potatoes: https://idahopotato.com/nutrition.