The same pesticides that poison the environment also pollute our bodies. Commonly used pesticides, such as organochlorines, are stored in our fat cells then released into our bloodstreams when we burn fat, disrupting the function of our mitochondria (our cells' energy-making furnaces).
In a 2004 study published in the International Journal of Obesity, researchers at Canada's Laval University reported that dieters with the highest levels of organochlorines had a greater metabolic slowdown as they lost weight than their peers with lower levels of the pollutant, likely because the toxins hinder the energy-burning process. Other studies have indicated that pesticides may actually contribute to weight gain.
More: 15 Ways to Speed Up Your Metabolism
Choosing organic over conventional foods can help keep your body and the earth clean and healthy, says David Joachim, coauthor of Fresh Choices, a guide to selecting the safest food.
Organic food is produced without using synthetic pesticides, petroleum or sewage-sludge-based fertilizer, bioengineering or ionizing radiation. Organic meat, poultry, eggs and dairy foods come from animals that are fed 100 percent organic feed and raised without antibiotics or growth hormones.
"Organic foods cost a little more," says Joachim. "But the toll pesticides take on our environment and health outweighs the higher price." But remember, just because something is organic doesn't necessarily make it healthy (Learn exactly When and Why Going Organic Works.)
More: Is Organic Better, Safer and More Nutritious?
Here's our guide to buying organic.
Fruits and Vegetables: "This is where organic matters most," says Joachim, "because we consume the pesticides along with the food." The Environmental Working Group has ranked common produce from highest to lowest based on tests done for pesticides on produce collected by the U.S. Department of Agriculture and the U.S. Food and Drug Administration.
According to the list, you're better off buying organic bell and hot peppers, carrots, celery, cucumbers, green beans, lettuce, potatoes, spinach, apples, cherries, imported grapes, nectarines, peaches, pears, raspberries and strawberries.
It's okay to buy conventional asparagus, avocadoes, broccoli, brussels sprouts, cabbage, cauliflower, eggplant, onions, okra, peas, mushrooms, radishes, sweet corn, tomatoes, bananas, blueberries, cantaloupe, grapefruit, U.S.-grown grapes, honeydew, kiwi, papaya, pineapples, plums, lemons, limes, mangoes, oranges, tangerines and watermelon.
More: Fruits and Veggies to Help You Hydrate