Unless you have a peanut allergy, eating a large amount of peanuts at one sitting will only add calories to daily your intake. Peanuts pack in calories and fat, but most of the fat is derived from heart-healthy sources (4.4g of polyunsaturated and 7.0g of monounsaturated fats per one ounce serving). According to Calorie King a one-ounce serving of roasted, salted peanuts contains 166 calories and 14 g of fat. Everything in moderation is a good advice, especially when you are trying to control your weight and two to four 1oz servings/week of peanuts can be part of a healthy diet.