Obese people produce more carbon dioxide than people of normal weight and contribute more to the raging global climate change crisis, according to a new scientific study published online last week in the journal Obesity. CO2 is the most abundant greenhouse gas (GhG) and is notorious for its ability to trap heat to create a natural greenhouse effect that warms our planet.
Researchers from the University of Copenhagen in Denmark estimated obesity contributes to an extra 700 megatons of CO2 emissions per year worldwide. This is surprisingly equivalent to about 1.6 percent of all human-caused emissions. The study also found being obese is linked to 20 percent more GhG emissions such as CO2, methane and nitrous oxide than being a normal weight.
“This has important implications for all those involved in the management of obesity,” said Faidon Magkos from the university’s department of nutrition, exercise and sports.
“Our analysis suggests that, in addition to beneficial effects on morbidity, mortality and health care costs, managing obesity can favorably affect the environment as well.”
The study pointed out that like other oxygen-dependent creatures, humans emit CO2 produced by metabolic processes necessary to live. For example, we exhale CO2 when we inhale oxygen.
The amount of CO2 produced by a species is determined by its average metabolic rate, average body size and the total number of individuals of the species. There are some 7.8 billion people in the world today compared to 1.9 billion in 1900.
The study found obese people produce more CO2 than those of normal weight, which seems a natural assumption on its face. Obese people consume far more food and beverages, which need to be produced and transported to them. Transportation of food and drink to obese people leads to more consumption of fossil fuels. This, in turn, means higher CO2 emissions related to food production and transportation for obese people, according to the study.
The study’s starting point is that obese people have greater CO2 production from oxidative metabolism than individuals with normal weight. To determine obesity, the study researchers calculated body mass index (BMI). A widely used method to determine healthy weight, BMI is a person’s weight in kilograms divided by the square of height in meters.
The study researchers used the standard definitions of obesity. This means a BMI of greater than or equal to 30 kg/m2. Normal weight as measured by a BMI is a reading of less than 25. Obese people have a BMI of 30 or above and almost always have a large amount of body fat in relation to their height.