Indian consumers feel the most guilty about their environmental impact even though they have a smaller average footprint than consumers in wealthy countries, a survey said Thursday.

The 17-nation study by the Washington-based National Geographic Society found a "major disconnect" as consumers in rich nations had the least sustainable lifestyles but also felt the least guilty about their impact.

The "Greendex" found that Indians had the most sustainable behavior, followed by Chinese and Brazilians. Americans ranked the worst, with Canadians coming second to last. The French ranked last in Europe.

Despite coming out on top, 45 percent of Indians -- more than any other nationality surveyed -- said they felt guilty about their impact on the environment. They were followed by Mexicans and Chinese, with 42 percent of consumers in each country expressing guilt.

"Consumers in these large emerging economies are the most likely to report that environmental problems are having a negative impact on their health today," the study said.

Americans were among the least sensitive about their impact, with 21 percent saying they felt guilty. Even fewer Australians and Germans felt guilty, with the Japanese placing last with 14 percent voicing guilt over their behavior.

The survey ranked nations based on consumption patterns in food, transportation and housing.

Indians were ranked as having the most sustainable behavior in part due to the cultural taboo about eating beef, whose production is a major source of carbon emissions blamed for climate change. Mexicans and Japanese had the biggest environmental impact through food, according to the study.

Indians also had the least impact in housing, followed by Brazilians who were by far the most likely to say they bought electricity from green sources. Biofuels are a major industry in Brazil.

Chinese consumers had the least environmental impact per capita from transportation, according to the study. Americans and Canadians ranked as having the most impact in both housing and transportation.

The polling was conducted by research consultancy GlobeScan, which surveyed around 1,000 people in each country.