For many people on a weight loss journey, shedding pounds is all about achieving a health goal. Most people typically use the threat of heart disease or diabetes as top reasons to slim down since being overweight can put someone at increased risk for both. However, there may be yet another reason to reduce your waistline: New research has linked excess weight to poor brain health.
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A new study examined the connection between waist size and cognitive health.
The latest insights come from a cohort study published on March 12 in the journal JAMA Open Network, in which a team of researchers hoped to compare how diet quality and abdominal fat could affect cognitive decline and overall brain connectivity.
To test this, they looked at data from 512 participants whose diets were monitored and data from 664 participants whose waist-to-hip ratio (WHR) was monitored to measure abdominal fat. The mean baseline age for both groups was 48 years old.
Participants in the diet group had the quality of their food intake measured using the Alternative Healthy Eating Index score (AHEI), which included three assessments over the study’s 11-year run. Those in the other group had their WHR recorded five times over 21 years. At an average age of 70, participants in both groups were given basic cognitive tests and had MRIs performed to measure the following:
- White matter structural connectivity (how different areas of the brain interact with each other)
- Hippocampal brain function (the part of your brain responsible for learning and memory)
Waist size did play a factor in brain health.
Results of the analysis were conclusive in two ways. The first was that participants with a healthier diet had better brain connectivity and better white brain matter health than those with lower AHEI. It also found that participants who improved their diets over the course of the study saw improvements in brain health, especially as it pertains to dementia and aging.
Secondly, researchers found that participants with a lower WHR at the start of the study had better cognitive function at the conclusion. Having a higher WHR in midlife was “associated with poorer working memory and executive function, through a pathway partially mediated by alterations in white matter connectivity.”
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The results could help with future treatments.
In light of the results, the study’s authors said they were optimistic it could have a significant impact on how we prioritize health.
“These findings have important implications for prevention strategies: improving metabolic health and dietary quality during midlife is critical for brain health and cognition in later life,” Sharmili Edwin Thanarajah, MD, one of the study’s authors, wrote in an accompanying commentary. “This message is alarming in light of the obesity pandemic.”
He goes on to explain that 43 of adults and 20 percent of children worldwide are overweight, with trends suggesting the problem will only get worse. He also pointed out the dietary findings and the implications they carry.
“The recent evidence that even brief exposure to an unbalanced diet rich in fat and sugar can directly alter brain function in healthy participants, it is crucial to integrate dietary guidelines into public health policies,” Thanarajah writes. “Such an integration should be an independent and essential strategy for protecting brain health, alongside the evaluation of metabolic and cardiovascular risk factors.”
The study had a few limitations.
The team admitted that more research on the topic might be necessary due to some limitations of the study. On one hand, they cited the fact that self-reported diet data could contain errors and that participants in the study might have been eating a less typical diet than expected. They also noted that most had higher than average education levels, meaning their diets were likely healthier than average.
But primarily, the fact that the participant pool was 80 percent male (as well as White and British) made it impossible to look at the effects of WHR on men and women separately.
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The takeaway:
Being concerned about your waistline isn’t just about combating heart disease and diabetes. New research found a connection between waist-to-hip ratio (WHR) and a decrease in brain health in participants, with those who had higher WHR in midlife showing changes in brain matter and performing worse on cognitive exams by the time they reached around 70.
The cohort study also looked at dietary impacts, finding that participants on less healthy diets in middle age also saw a decline in brain health by the study’s end. The researchers concluded that the results could help with treatments going forward.
“These findings suggest that interventions to improve diet and manage central obesity might be best targeted in midlife (ages 48-70 years) to obtain beneficial outcomes for brain and cognitive health in older age,” Thanarajah wrote.
