You watch the number of burgers you chow and limit the sweets. But when's the last time you thought about eating too many nuts? Likely never, especially with recent headlines touting how eating them prevents disease and extends life span. The problem: A serving has an average of 170 calories and 15 grams of fat. Factor that into the daily 2,700 calories and 82 grams active men should aim for, and you can see how it's easy to overindulge. Here, what a serving actually looks like for five common nuts, and the other benefits they confer.