A meta-analysis published in August 2026 in the International Journal of Food Sciences and Nutrition found that sarcopenia, the natural loss of muscle mass, strength, and function that occurs with aging, is associated with a 42% higher risk of developing dementia. The study, led by Uraiporn Booranasuksakul and Mario Siervo from Curtin University, reviewed more than 80 cohort studies and identified sarcopenia as the most consistent sign of declining brain health across different populations. The findings suggest that muscle loss may be a better predictor of dementia risk than weight, which has long been considered a key factor in health assessments. Before the age of 65, obesity is associated with a slightly higher risk of dementia, around 9%, but after 65, being overweight is linked to a reduced risk of 17%. Researchers believe this reversal may be due to an energy reserve in older adults that could benefit brain function. However, the relationship between sarcopenia and obesity is still unclear. Only four studies have looked at this connection and found no clear link to dementia. The study emphasizes that while observational research identifies associations, it does not prove that weakened muscles cause dementia. It is possible that factors like inactivity or poor diet could harm both muscles and brain cells at the same time. The researchers suggest that maintaining muscle strength through regular physical activity and a sufficient intake of protein may support both muscle and brain health. They note that future studies are needed to determine whether preserving muscle mass can slow cognitive decline. These questions can only be answered through long-term trials that track individuals over many years.