Is the lower-calorie version of a food your best bet? Not necessarily. When I started dieting, I always went for the lower-calorie choice; but as I learn more and more about food, I realize that it's not always the better or healthier choice. Here are a few "foods for thought:"

White Potatoes vs. Sweet Potatoes
White potatoes have 77 calories per 100 grams, while sweet potatoes have 86 calories for the same amount. So, gram for gram, they're pretty close calorie-wise; however, the sweet potato contains large amounts of the antioxidant beta carotene (vitamin A), is a good source of vitamin B6 and has a lower glycemic load in spite of its sweetness. And while they both have fiber, the sweet potato wins here, too. On the other hand, while both are fine sources of potassium, the white potato is slightly better. And even though they both have vitamin C, the white potato has significantly more.