Is air pollution making you fat? Understanding the hidden impact

The annual spike in AQI (air quality index) after Diwali has become a familiar phenomenon in north India, especially in the national capital region. While air pollution has long been linked to respiratory and cardiovascular issues, research also suggests it could contribute to rising obesity rates.
Studies show that prolonged exposure to particulate matter, nitrogen dioxide, and carbon monoxide, could lead to systemic inflammation and metabolic disturbances, factors that are key in weight gain and obesity. Fine particulate matter (PM2.5), which enters the bloodstream, influences metabolism rates, according to the studies.
However, the link between ambient air pollution and weight gain or obesity is also dependent on varying populations, types and severity of pollution.
WHAT IS OBESITY AND HOW IT AFFECTS THE BODY?
Obesity is a medical condition marked by excess body fat, often due to an imbalance between calorie intake and energy expenditure. It increases risks for diabetes, heart disease, and other health issues. It is a chronic condition highlighting a complex physical and mental disease.

Obesity is a medical condition marked by excess body fat, often due to an imbalance between calorie intake and energy expenditure. (Photo: Getty Images)

Since 1975, the number of obesity cases in the world have tripled. The Global Burden of Obesity Study shows that the number of deaths due to high Body Mass Index (BMI) more than doubled globally from 1990 to 2017.
Obesity is a symptom of type 2 diabetes, heart disease, stroke and kidney problems. A body mass index of 30 or higher indicates obesity.
As per the World Health Organisation (WHO), in 2019, around five million non-communicable disease deaths were caused by high BMI.
THE AIR POLLUTION AND OBESITY LINK
There’s growing evidence that air pollution is one of the risk factors for obesity.
A 2021 study conducted among Spanish children has also revealed that increase in air pollution, road traffic noise was associated with childhood obesity.
Dr Vikas Maurya, Senior Director, Department of Pulmonology and Sleep Disorders, Fortis Hospital, Shalimar Bagh, New Delhi, said as children and adolescents were more active and breathe in more air, they were more likely to be associated with obesity than adults. “This is itself a serious concern,” said Dr Maurya.
A meta-analysis published in BMC Public Health found that air pollution can impact metabolic function by influencing inflammation in fat tissue, increasing oxidative stress, and altering individual dietary habits.Breathing toxic air affects immune function and breathing pathways. This raises inflammation markers and increases oxidative stress. Besides this, in a study, PM2.5 exposure was found to have a “negative effect on glucose metabolism”. This affects weight gain.

As children and adolescents were more active and breathe in more air, they were more likely to be associated with obesity than adults. (Photo: Vani Gupta/India Today)

Another study published in Environmental Research suggested that air pollutants might also indirectly impact body weight by raising the risk of chronic conditions like high blood pressure, heart disease, and lung disease.
“Exposure to higher concentrations of air pollution was associated with higher resting blood pressure and lower ventilatory function. Ozone was associated with reduced exercise capacity,” researchers of the study wrote.
Air pollution can cause metabolic disorders that lead to weight gain. “It also raises inflammation in the body, further leading to obesity. One of the most important reasons for it causing weight gain is by restricting movement,” said Dr Shailly Sharma, senior consultant and associate director, obstetrician and gynecologist, Cloudnine Hospital, Faridabad.
She added that since polluted air causes coughing, shortness of breath can restrict physical activity, which is another cause of weight gain.
Although a link has been established between air pollution and obesity, more studies are needed to provide a better understanding of how different pollutants are affecting hormonal health and metabolism.