You can toss your empty soda cans in the recycle bin instead of the garbage, saving energy and reducing landfill. Or you can wear hemp clothes and drive a hybrid car plastered with bumper stickers requesting the salvation of everything from owls to dust mites.

There are lots of little ways to go green, but if you really want to help save the Earth, you can start by dropping a few pounds.

It's no secret that obesity has plenty of personal health consequences; the list of diseases that have been associated with being overweight include higher risk of high blood pressure, diabetes, heart disease, stroke and less sex, to name only a few. But being fat also has consequences for our planet—often in ways we might not expect.

The fact is that lean is green, and larger people leave larger carbon footprints on the world. A few examples:

Food consumption

There's an old joke about a mother telling her son to finish the food on his plate because there are starving children in Africa. The smart-aleck's response is, "Got a stamp?"

What's not a joke is that there is a finite amount of food in the world, and it is growing scarce. Recent food riots Haiti, Sudan, Yemen, Mexico, Egypt, and other countries are a stark reminder that many people do not have enough to eat. The cost of staple foods such as corn, rice, and wheat are at record highs across the globe, and some can't afford to feed their families.

Meanwhile in the United States, obesity is at an all-time high; two-thirds of adults in the Land of Plenty are overweight or obese. Obesity is perhaps the ultimate symbol of resource consumption; it's visible proof that overweight people already has more than they need—and take more anyway.

The causes of food shortages are varied and complex, but if Americans simply ate less food, there would be more for the rest of world. By some estimates, the average American consumes about 4,000 calories per day; that's twice what they need. Those 2,000 fewer calories would be available for those who truly need the food, and help to conserve Earth's natural resources.

Air pollution

Overweight people create more air pollution than thin people do. It's simple physics: Extra pounds translate into extra fuel in automobiles and airplanes. Extra fuel means increased energy usage, oil drilling, and air pollution.

A 2004 study by the Centers for Disease Control and Prevention found that for every ten pounds gained by the average American, airlines burned 350 million more gallons of fuel to carry the additional weight. That fuel spewed an estimated 3.8 million extra tons of carbon dioxide into the air.

And as for that smaller hybrid car? It's a good start, but there's not much point in buying fuel-efficient vehicles if you're going to fill that large seat with your extra-large butt; you might as well throw a few sandbags in the trunk. Fuel efficiency drops dramatically with more weight the engine has to pull; the lighter you are, the less gas you burn, the more money you save, and the less pollution you emit.

Of course, going green by going lean is easier said than done, and only part of the problem. But by getting ourselves healthier we also help save the planet. Not a bad deal.

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Benjamin Radford is managing editor of the Skeptical Inquirer science magazine. His books and films can be found on his website.