Iceberg lettuce gets a bad rap for being nutrient poor.  It isn't.  It's just slightly less nutrient rich than many other leafy greens.  One serving (2 or so cups) is 20 calories, a gram and change of protein, 4g carbs, and almost 2 g of fiber (and then for micros, you've got 2-4% of vitamin a and iron, and calcium, I believe) You could do better, sure.  But you could do a lot worse.