Qat leaves in a bag for sale on the streets of Sanaa, Yemen. (From the book What I Eat: Around the World in 80 Diets.) Although qat chewing isn't as severe a health hazard as smoking tobacco, it has drastic social, economic, and environmental consequences. When chewed, the leaves release a mild stimulant related to amphetamines. Qat is chewed several times a week by a large percentage of the population: 90 percent of Yemen's men and 25 percent of its women. Because growing qat is 10 to 20 times more profitable than other crops, scarce groundwater is being depleted to irrigate it, to the detriment of food crops and agricultural exports.