‘Skinny fat’ is a term used to describe someone who is a relatively small size, but has low muscle tone. Some people might call those who are ‘skinny fat’ lucky—they can put away cheeseburgers and fries without worrying about whether it might make them go up in pants size. But a new study from Florida Atlantic University found that the so-called ‘skinny-fat’ set is not immune from the health risks that come with obesity—and they may even be at a greater risk for dementia.
Most people think of obesity as being obvious. But even a size 2 can be obese if their muscle mass is low enough and their overall fat content is high enough. In older people, this condition happens often enough that it has an official name: sarcopenia. Sarcopenia is considered a natural part of the aging process that leads to a loss in muscle tissue. But combined with obesity, sarcopenia can have a dangerous effect on brain health.
Experts looked at data from 353 people with an average age of 69 who were considered skinny fat (or ‘sarcopenic obese’ in technical terms). They compared their muscle mass, body mass index and fat content with several functional and cognitive tests: the Montreal Cognitive Assessment, or MoCA, which is often used to test for dementia, recognition tests that involved naming animals and tests that measured function, like standing up from a chair and gripping objects.
Individuals with both low muscle mass and high fat content did the worst on the cognitive tests. Individually, both low muscle mass and obesity had a negative effect on cognitive performance, too. “Their coexistence, however, can pose an even higher threat likely surpassing their individual effects,” wrote the study authors. People with sarcopenic obesity had trouble with executive function, memory and speed—all early symptoms of Alzheimer’s disease.
Most health experts consider more than 25 percent body fat for men to be obese, and 35 percent body fat for women. The good news: Balancing muscle mass is as easy as starting a weight training program or cutting fatty foods from your diet. For older women, studies have shown that even a light yoga regimen twice per week can maintain muscle. In another study, researchers found that upping protein intake helped older men maintain muscle mass. Study authors hope this research might inspire programs targeted at seniors who are at risk of losing muscle mass as they age.
“Understanding the mechanisms through which [sarcopenia] may affect cognition is important, as it may inform efforts to prevent cognitive decline in later life by targeting at-risk groups with an imbalance between lean and fat mass,” said study author and neuroscientist James E. Galvin, M.D. “They may benefit from programs addressing loss of cognitive function by maintaining and improving strength and preventing obesity.”
This study doesn’t prove that being skinny fat causes Alzheimer’s—just that there is an association between it in older adults and the markers of Alzheimer’s disease. The study did not follow people long enough to see if they developed dementia, but it does shed light on the potential relationship between obesity, muscle mass and cognitive function.
This study was published in the journal Clinical Interventions in Aging.