It?s not easy to get proper nutrition with ?natural food? alone. Shakes and bars are convenient and cheap, when compared with a stake dinner.
Of course it's easy to get "proper nutrition" with real food. After all, that's what humanity evolved eating, so by definition that's "proper" for us. One just has to pick what s/he eats with a modicum of sense. Besides, an engineered food type product that's lacking vitamins in their natural context isn't going to result in proper nutrition, either. Maybe I'm being Luddite here, but I see lots of friends eating bars and drinking various powdered shakes and I can't help but worry about the long-term health problems that may result from such an unnatural chemical diet. (When I make a smoothie, I tend to use real -- frozen instead of fresh, but still real -- fruits and yoghurt with perhaps a dab of honey, nothing more or less.) As for the cost/time difference, I think it's overstated. For instance, I often bring a salad to work for lunch. My preferred method of making such a salad is to take a prewashed bag of organic lettuce, add some taste-enhancing stuff (various organic veggies, depending what's in season, but often bell peppers, tomatoes, bell peppers, and mushrooms; often pine nuts, sunflower seeds, pecans, or walnuts; occasionally a can of tuna fish; and almost always pumpkin seed oil and balsamic vinegar as dressing) put it in a closed container, and shake the hell out of it. Total time invested in preparation: about three minutes. Sure, it takes longer to eat than a bar, but it also, um, tastes like food. A chicken breast isn't any more expensive than synthetic food, and at home is easy to cook, just throw it on the ubiquitous George Foreman grill for 5-6 minutes and you're done. Salmon or other types of fish are little more expensive, but usually just as easy to cook. For lunch at work, it's easy to just bring some pre-cooked stuff and microwave it. For steaks, I go to a private butcher who also supplies to the two best steakhouses in town, and pay reasonable prices for absolutely incredible cuts of meat. When I'm feeling lazy, I'll just throw in on the George and enjoy a wonderful piece of meat. I do tend to eat steak at least once a week, although I eat fish much more often. The flip side is that developing a unique cooking style through personal trial-and-error, is, well, it's an incredibly effective chick magnet.