Older obese people have brains that appear 16 years older than their peers who are of a healthy weight, according to new research.

Researchers from the University of California Los Angeles looked at the brains of 94 individuals aged 70-79 for their report in Tuesday’s online edition of Human Brain Mapping. Overweight seniors had roughly 4% less brain tissue, and their brains aged prematurely by eight years. Meanwhile, obese seniors has 8% brain matter loss, which researchers called “severe brain degeneration.” These brains looked 16 years older than those of thinner individuals. Much of the brain loss was found in the frontal and temporal lobes, which control planning and memory. Other areas of brain matter loss include the hippocampus, which is associated with long-term memory, and the basil ganglia, which helps control movement.

The distinction between “overweight” and “obese” depends on an individual’s body mass index. A BMI of 25-29 is overweight and 30 and over is obese. The World Health Organization estimates a combined 1.3 billion people worldwide are either overweight or obese.