Is a lack of impulse control related to weight gain? New research from New York University (NYU) and the Italian National Institute of Health suggests it might be – especially for people with attention deficit hyperactivity disorder (ADHD).

Published in PLOS Complex Systems, the study found that ADHD may raise obesity risk through both behavioral and biological pathways, and that this link changes depending on where someone lives.

How ADHD and obesity are connected

ADHD and obesity are two common and growing health problems. They’re often studied separately, but research shows that they may be connected. People with ADHD tend to be more impulsive and less physically active – traits that can also increase the chances of gaining weight. Studies have suggested that ADHD may raise the risk of obesity, especially in children.

Currently, most of this research has focused on individuals – looking at personal traits, behaviour or family background. But it hasn’t paid much attention to the environments people live in. However, health is shaped not just by who someone is or what they do, but also by where they live.

Urban features like food access, mental health care, public spaces and education levels could all influence the link between ADHD and obesity, but studies rarely include these wider factors. As a result, there isn’t a clear picture of how city living might affect this relationship.

The new study aimed to explore the connection between ADHD and obesity at two levels: across U.S. cities and among individual children. The team looked at how features of the urban environment might shape or shift this link. Do some places make the effects of ADHD on physical health better or worse?

City size and resources shape the ADHD–obesity link

The researchers looked at data from 915 U.S. cities to examine how common ADHD and obesity are, and how that varies with city size. They also measured how much each city’s rates of ADHD and obesity differed from what would be expected for its population, and whether those differences could be explained by local factors, such as access to mental health care, education levels, food insecurity and physical activity.

The team found that both conditions are less common in larger cities.

To test how these factors might be connected, the team used a causal modeling technique. They proposed a pathway where ADHD leads to reduced physical activity, which in turn increases the risk of obesity.

They found that this chain was stronger in cities with fewer health and lifestyle resources, and weaker where mental health care and education were more widely available.

They also tested the pattern using data from 19,428 children.

The individual-level results matched what was seen at the city level. Children with more severe ADHD symptoms were less physically active and more likely to be obese.

Higher education levels were associated with lower obesity risk, directly and indirectly, and food insecurity made the ADHD–obesity connection stronger.

The analysis also pointed to a second pathway: ADHD contributing to obesity directly through traits like impulsive eating.

This pathway may involve differences in brain systems linked to impulse control, such as dopaminergic signaling, making the relationship between ADHD and obesity more than just behavioral.

The team found that bigger cities seemed to offer some protection; ADHD and obesity were both less common, and the link between them was weaker.

“Our research reveals a surprising urban advantage: As cities grow, both obesity and ADHD rates decrease proportionally,” said lead author Tian Gan, a PhD candidate at NYU.

“Meanwhile, mental health services become more accessible, helping combat physical inactivity – a key link between ADHD and obesity,” she added.

Urban design matters for ADHD and obesity

The study suggests that where a child lives can shape how ADHD affects their risk of becoming obese. City environments can either make this link worse or help weaken it. Improving access to mental health services, creating more opportunities for physical activity and addressing food insecurity could all help reduce obesity, especially for kids with ADHD.

“These findings underscore the importance of city-level interventions in mitigating the impact of impulsivity disorders on the obesity epidemic,” said senior author Dr. Maurizio Porfiri, an institute professor at NYU.

The findings also point to a more complex relationship than previously thought. ADHD doesn’t just influence obesity through a lack of movement, it also has a more direct biological link.

“Surprisingly, we discovered ADHD influences obesity through dual pathways: reduced physical activity and independent biological mechanisms related to impulse control and eating behaviors – indicating that effective interventions need to address both aspects,” said co-author Dr. Simone Macrì, a researcher at the Italian National Institute of Health.

“Supporting physical activity, especially in children with ADHD, could significantly improve long-term health outcomes,” Macrì added.

Reference: Gan T, Succar R, Macrì S, Porfiri M. Investigating the link between impulsivity and obesity through urban scaling laws. PLOS Complex Syst. 2025;2(5):e0000046. doi: 10.1371/journal.pcsy.0000046

This article is a rework of a press release issued by PLOS. Material has been edited for length and content.