With new studies appearing daily on the effects of this diet or that food, it gets hard to know exactly what constitutes a healthy diet. This month's Scientific American has an excellent article by Marion Nestle, renowned nutrition professor and author of What to Eat. Her answer to the good eating dilemma is pretty straightforward: "eat less, move more, eat a largely plant-based diet, and avoid eating too much junk food," and as she says, we've known this for a while now. But she also includes a discussion of how studies of single nutrients and the influence of the food industry on research and consumer behavior have muddied the waters considerably.

One great sidebar is her take on the newest food pyramid. She notes that the vague color scheme and absence of clear-cut advice on foods to avoid makes the pyramid, well, pretty unhelpful. Why is this pyramid so much more flawed than the 1992 version? Nestle and others suspect the influence of the food lobbies, who prefer the that government doesn't tell consumers to stay away from their products. In other words, what is good for the bottom line of food companies is pretty sucky for the rest of us.