Obesity is known to have negative consequences for human health, but a recent study indicates that it can be just as detrimental to the health of the planet. Researchers at the London School of Hygiene and Tropical Medicine suggest that overweight people are more likely to be responsible for carbon dioxide emissions than lean people.
Phil Edwards and Ian Roberts approximate that each overweight person generates about one tonne of carbon dioxide per year more than a slender person. Accordingly, a lean population of one billion would emit 1,000 million fewer tonnes of carbon dioxide per year than an overweight population of the same size.
Heavier people require more food. Energy expenditure increases with rising body mass index (BMI), which means that a heavier population requires 19 percent more food energy for its daily energy requirement, according to Edwards and Roberts. The greater the population of obese people, the more food that needs to be produced, which could increase fossil fuel use in the agricultural sector – which already contributes one-third of all greenhouse gas emissions worldwide.
Obesity also increases carbon dioxide emissions through extra strain on transportation. The overweight population requires additional fuel to move heavier bodies. Edwards and Roberts assume that extra fuel energy from vehicles used by the overweight population increases annual greenhouse gas emissions between 0.4 gigatonnes and 1.0 gigatonnes per year. This estimate is based on the interplay between increased car use, greater energy input needed to move heavy people, and decreased physical activity.
The authors of the study also released a book in 2010 entitled The Energy Glut. The book links obesity to climate change, demonstrating a positive feedback loop. Fossil fuels promote convenience, which ultimately causes obesity, while obesity generates excess fossil fuel use.
Edwards and Roberts suggest that transportation policies that encourage human-powered travel methods, such as walking and bicycling. They see this as a crucial element of future food policy:
“Urban transport policies that promote walking and cycling would reduce food prices by reducing the global demand for oil, and promotion of a normal distribution of BMI would reduce the global demand for, and thus the price of, food. Decreased car use would reduce greenhouse gas emissions and thus the need for biofuels, and increased physical activity levels, would reduce injury risk and air pollution, improving population health.”