Study Reveals Increased Brain Size in Obese Teenagers

Recent research presented at the European Congress on Obesity (ECO 2025) indicates that certain brain regions are larger in teenagers suffering from abdominal obesity. This study highlights potential implications for cognitive functions such as learning, memory, and emotional regulation.

Lead researcher Dr. Augusto César F. De Moraes from UTHealth Houston School of Public Health emphasized the significance of these findings, noting that the teenage years are crucial for brain development. The study draws attention to the alarming rise in obesity rates among children and adolescents globally, with a reported increase of over fourfold in obesity prevalence among both girls and boys from 1990 to 2022.

In the United States alone, more than one-third of children aged 5 to 14 are classified as overweight or obese, amounting to over 15 million children. Abdominal obesity has been previously associated with alterations in brain development, particularly affecting areas crucial for cognition and emotional management.

To investigate the relationship between obesity and brain structure, Dr. De Moraes and his team analyzed data from 3,320 adolescents participating in the ongoing ABCD study, which examines how childhood experiences impact health and brain development. Participants were recruited from various cities across 17 states and were monitored over four years. At the outset, nearly 34.6% of the subjects were identified as having abdominal obesity, determined through waist circumference measurements.

Using structural MRI scans, the researchers assessed the volume of critical brain regions within the subcortex, including the amygdala, hippocampus, caudate, accumbens, pallidum, putamen, and thalamus. Findings revealed that certain brain regions, particularly the hippocampus and amygdala, were significantly larger in adolescents with abdominal obesity compared to their peers without this condition. Specifically, the hippocampus exhibited an increase of approximately 6.6%, while the amygdala showed a growth of about 4.3%.

Notably, adolescents with extremely high levels of abdominal fat, assessed by a waist-to-height ratio exceeding 0.5, had even larger amygdalae, raising concerns about how excess body fat may influence emotional processing. In contrast, the thalamus and caudate experienced minor increases in size.

The study also underscored the impact of socio-economic factors on brain development. Teens from lower-opportunity areas demonstrated less development in key brain regions, including the hippocampus and amygdala, compared to those from higher-opportunity environments. This disparity was particularly evident among adolescents with persistent abdominal obesity.

Dr. De Moraes noted that both underdevelopment and excessive growth in brain regions could be detrimental, highlighting the importance of addressing social inequalities and health risks to foster not only physical health but also optimal brain development in young people.

The implications of this research extend beyond childhood, as the alterations in brain structure may pose risks for cognitive issues later in life, including memory problems or even dementia. Therefore, promoting healthier lifestyle choices during adolescence is crucial for improving both physical and mental well-being.