Today’s USA Today has several terrific stories about how hard it is to know where our food comes from and why it matters that we do. The cover story in the Life section follows Phil Lempert, the supermarket guru, around a store reading package labels to try to figure out the origins of ingredients. A second piece lists where specific foods come from. Dairy, peanut butter, bread, and soda pop are All-American, but Brazil is the number one source of orange juice. And who knew that fresh and frozen fruits and vegetables head the list of imported foods and Mexico is the leading source? A third story, in which I am quoted, discusses Country of Origin Labeling (COOL), a law passed by Congress years ago but endlessly postponed under pressure from food industries. Only supermarket fish are required to list the country that caught or farmed them, and as far as I can tell, this is a law ignored more often than not. If Congress doesn’t get its act together and put COOL into action, we won’t have a clue where our food comes from. Why do we need to know? Safety and miles traveled, for starters. Ever heard of COOL? It’s worth writing your representatives for this one.

I’ve just been asked if I’ve seen King Corn. Indeed I have and highly recommend it. It’s great fun. Two guys buy an acre of land, plant corn on it (a scene well worth the price of admission), watch it grow, harvest it, and film the process. I adored the scene that shows how they make their very own high fructose corn syrup, the planting scene of course, and the very last one (which I won’t spoil). You can read about it on the King Corn website. It’s going into distribution. Has anyone else seen it? What did you think?

I am at the Festival of Ideas in Adelaide this week and checked out the local supermarket. Shrek was everywhere. I counted at least ten special displays of Shrek-illustrated foods positioned at the ends of 5 aisles, along one entire wall (with a blow up Shrek doll), and in stand-alone areas. Shrek III has arrived in Australia but does Australia really need a store full of Shrek-green Froot Loops (devoid of fruit, of course), Shrek cheese-flavoured snacks, Shrek-illustrated chocolate flavoured biscuits, and Shrek candies? And a local McDonald’s also has a Shrek tie-in. This is about one thing and one thing only: marketing junk food to kids. Not a good idea.

This question just in: “Dear Dr. Nestle, could you suggest a diet, book, or website that would offer correct advice on how to lose weight? I am so confused about all the different types of diets and would appreciate your valued input. I am a 52 year old male with familial hypercholesteremia who needs to lose about 30 lbs….”

I try to steer clear of medical nutrition advice (see your doctor for that) but the general approach to diets is easy because the same way of eating works for just about any health problem: Eat less (if you have a weight issue); move more; eat plenty of fruits, vegetables, and whole grains; don’t eat too much junk food; and enjoy what you eat! Although I wrote What to Eat as a guide to thinking about food issues, more and more readers tell me they are losing weight after reading the book—the range is 5 to 80 pounds so far. That’s terrific, if true. Let me know!

I always worry that when it comes to preventing childhood obesity, food companies that make junk foods for kids are stuck. They must continue to increase sales every quarter in order to please stockholders. This requirement forces them to engage in contradictory activities. Take a look at what Parke Wilde, a professor at Tufts, has to say on his blog about Kellogg’s new Froot Loops cereal straws and decide for yourself.

A reader asks what might be the ideal percentage of protein, fat, and carbohydrate in diets. It’s not an easy question to answer because the percentages could vary a lot, depending on the amounts of good fats (monounsaturated, for example) and good carbohydrates (whole grains). In any case, it’s too hard to have to look up the nutrient composition of every food you eat. But I sometimes have fun using the USDA’s food composition tables. They do require interpretation though as the numbers may or may not reflect what you are actually eating. Carrots grown in California may or may not have the same nutrient composition as those grown in upstate New York. I consider these tables a national treasure and wish the USDA would put more resources into making them even more comprehensive.

I was recently interviewed for a story on “10 things your grocery store doesn’t want you to know” (see it at msn health and fitness). The writer had some fun with What to Eat and honed in on the take home lessons and then some. She also quotes Brian Wansink, whose book, Mindless Eating, is one I assign to students to explain how something as simple as a large plate encourages people to eat more calories. Enjoy!

I participated in a panel with Charlie Rose last night on the science of obesity. With five people around the table, it was hard to get a word in edgewise, but I did the best I could (take a look and judge for yourself). The central issue for the conversation was whether obesity is the result of genes or the environment. If it’s genes, let’s find a drug and solve the problem. If it’s environment, things get much more complicated because no drug can fix a society that makes food available everywhere, at rock bottom cost, in enormous portions. Genes matter, of course; not everyone who overeats gains weight. But rates of overweight started to zoom up just in the past 25 years or so, too recently for genetics to have changed. While the science types are working hard to find a magic–and highly profitable–bullet, people need to find ways to handle a food environment that encourages overeating. I’m in favor of policies to make it easier to eat more healthfully, ranging from restrictions on marketing junk food to children to elimination of farm subsidies. I’m sure you can think of more. I’m collecting a list. Send suggestions.

In the meantime, I have a bit more to say about these issues at Eating Liberally.