Here's another reason to watch your waistline: It could impact the functioning of your brain, according to a new study.
The findings, published in the journal Neurology, show that people who are obese and have hypertension, low "good" cholesterol levels, high triglycerides or high blood sugar (what are known as "metabolic abnormalities") are more likely to experience cognitive decline at a faster rate than people without any of these conditions.
The research included 6,401 people -- average age of 50 -- whose BMI and health risk factors were noted at the beginning of the study.
Of all the study participants, 31 percent had at least two metabolic abnormalities. Nine percent of the study participants were considered obese, while 38 percent were considered overweight. And among those who were obese, 60 percent of them also had the metabolic abnormalities.
Then, researchers had the study participants take memory and brain functioning tests three times over a 10-year period.
They found that the people who were obese and had the metabolic abnormalities experienced a faster rate of mental decline of 22.5 percent over the 10-year period, compared with the healthy, normal weight study participants.
People who were obese but didn't have metabolic abnormalities were not off the hook, though -- their rate of mental decline over the 10-year period was still faster than the healthy, normal weight participants, researchers found.
Similarly, a recent study in the journal Age and Ageing showed a link between BMI and performance on cognitive tests. Korean researchers found an association between higher BMI in the older study participants (between ages 60 and 70) with worse scores on the tests, HuffPost UK reported.
"We have all heard how a high BMI is bad for our heart but this research suggests it could also be bad for the head," Clive Ballard, of the UK Alzheimer's Society, told BBC News. "Although we don't know whether the people in this study went on to develop dementia, these findings add to the evidence that excess body fat could impact on brain function."