Although most people are obsessed with losing weight, there are those who would like nothing more than to pack on a few more pounds. Raisins are one of the best choices for intentional weight gain, as they are very rich in nutrients, as well as calories. A few extra handfuls of raisins a day could increase your daily caloric intake by 400-500 calories, which will make gaining weight much easier. However, raisins are a healthy way to gain weight because they also possess a range of beneficial nutrients, such as iron, magnesium, vitamin B and calcium.