Eating less meat is the solution to a slimmer physique and a happier planet, says the author of a new book that seeks to change the way we think about food.

Mark Bittman, the New York Times food writer and author of "Food Matters", says the industrial production of livestock is responsible for 18 per cent of the world's greenhouse gases.

By reducing the amount of meat we eat, he told CTV's Canada AM, we can have a direct and positive effect on the environment.

"In as big a way as switching to a Prius or using high-efficiency light bulbs or turning off the lights when you leave home or wearing a sweater in winter. It's another one of those small steps we can all take to have a positive impact on the environment," Bittman said.

He cited the clear-cutting of forests to make room for fields for cattle, the environmental impact of slaughterhouses, transportation costs and the sheer amount of methane gas emitted by cattle herds, as damaging to the planet.

On top of that, roughly 50 per cent of the corn and soy grown in the U.S. is used for animal feed, requiring incredible amounts of energy to produce and transport.

But Bittman isn't just a green geek, he's also a health nut, and says his book maps out a way to do both.

"It's so simple. It's really about changing the proportions of the food that we eat. And we North Americans eat a huge amount of meat, highly processed foods and relatively very, very little plants."

He said the average person gets between 80 and 90 per cent of their caloric intake from meat and processed food, and just 10 to 20 per cent from plants.  

In the U.S., he said, people get an average of 7 per cent of their daily calories from drinking pop. Cookies, doughnuts and cheeseburgers, not surprisingly, are also high on the list.

When the ratio of meat to plants is shifted by 10 to 20 per cent, the results are dramatic, he said.

Bittman cut his own meat intake by two-thirds, and reduced his intake of processed foods and dairy products and "tried to really gorge on plants", such as fruits, vegetables, whole grains and legumes.

"I lost 35 pounds, no kidding," Bittman said.

"My cholesterol went down, my blood sugar went down. I wasn't even trying to lose it, I wasn't paying attention. And a month after I started eating this way I'd lost 15 pounds and... then another month later I'd lost another 15 pounds and over the next year I lost a few more."

But Bittman is clear, he isn't trying to sell his book as a dieting guide or a "two weeks to 15 pounds weight loss kind of thing."

"It's really a different way of thinking about and handling and eating food and it's a lifelong thing."