A new study published in the journal Neurology has uncovered a significant connection between body composition and the risk of developing neurodegenerative diseases such as Alzheimer’s and Parkinson’s.
The research highlights that the distribution and quality of body fat and muscle play a more critical role in determining disease risk than overall weight alone. People with high levels of body fat stored in the belly or arms are more prone to these diseases, while those with greater muscle strength have a lower risk.
This discovery adds to the growing body of evidence emphasizing the importance of body composition in understanding the broader health implications of obesity. The findings suggest that rather than focusing solely on overall body weight, it is the specific location of fat deposits and the presence of muscle that significantly impact the likelihood of developing neurodegenerative diseases.
The Impact of Body Composition on Disease Risk
The study was led by Dr. Shishi Xu, a researcher at Sichuan University’s West China Biomedical Big Data Center in Chengdu. Dr. Xu and her team analyzed health data from over 400,000 people, with an average age of 56, who were free of neurodegenerative diseases at the start of the study. Various body composition metrics were assessed, including waist and hip size, grip strength, bone density, and fat and lean mass.
Over the course of approximately nine years of follow-up, around 8,200 participants (roughly 2 percent) developed neurodegenerative conditions such as Alzheimer’s, other forms of dementia, and Parkinson’s disease.
After accounting for other contributing factors like high blood pressure, diabetes, smoking, and alcohol consumption, the researchers found that participants with high levels of belly fat were 13 percent more likely to develop these diseases than those with lower belly fat.
Additionally, individuals with a higher percentage of fat in their arms were 18 percent more likely to develop neurodegenerative diseases compared to those with less arm fat.
Conversely, muscle strength was shown to offer a protective benefit. Participants with greater muscle strength were 26 percent less likely to develop these diseases compared to those with lower strength.
Dr. Xu explained, “We consistently observed an increased risk with ‘central obesity’ [characterized by fat mass mainly in the torso] and ‘arm-dominant fat distribution’ patterns, and a reduced risk with the ‘muscle strength’ pattern, in both clinical neurodegenerative disease onset and brain aging markers.”
Understanding the Role of Fat and Muscle
The findings highlight the different roles that fat and muscle play in the aging process and the development of neurodegenerative diseases.
Dr. Yuko Hara, director of aging and Alzheimer’s prevention at the Alzheimer’s Drug Discovery Foundation, was not involved in the study but offered insights into why these body composition patterns might affect disease risk.
“Belly fat can harm the brain because it produces hormones and chemicals that promote inflammation, insulin resistance, and vascular issues, which all contribute to cognitive decline and dementia risk, as well as cardiovascular disease risk,” Dr. Hara explained.
In contrast, fat stored around the hips and thighs has been associated with better insulin sensitivity and reduced inflammation, offering some protection against these diseases.
Dr. Hara also noted that midlife obesity is one of the 12 modifiable lifestyle factors associated with an increased risk of dementia, as identified by the Lancet Commission on Dementia Prevention, Intervention, and Care.
Muscle strength, on the other hand, plays an essential role in physical fitness and metabolic health, both of which contribute to reducing inflammation and improving cardiovascular function.
Dr. Joel Salinas, clinical assistant professor of neurology at NYU Langone Health and chief medical officer at Isaac Health, explained, “Muscle strength is associated with better physical fitness and metabolic health, which can reduce inflammation and improve cardiovascular function.”
Moreover, individuals with high arm fat often have lower muscle mass, which suggests reduced physical activity—a risk factor that further increases the likelihood of developing dementia. This highlights the importance of maintaining muscle strength to protect against neurodegenerative conditions.
The Potential for Lifestyle Changes to Lower Disease Risk
While the study presents compelling evidence about the relationship between body composition and neurodegenerative diseases, it was not based on clinical trials, meaning more research is needed to determine whether these factors directly cause diseases or are merely early indicators of risk.
Nevertheless, the study’s findings provide a valuable framework for individuals who are looking to understand and potentially reduce their risk of developing Alzheimer’s or Parkinson’s. By focusing on improving body composition—reducing fat while building muscle—people may be able to lower their chances of developing these neurodegenerative conditions.
Dr. Xu emphasized that the focus should shift from overall weight loss to improving the quality and distribution of fat and muscle. “In recent years, due to the widespread use and even abuse of weight loss drugs such as semaglutide, people have become overly concerned with overall weight and often overlook the key role of different body compositions,” Dr. Xu explained.
“We want to emphasize that the quality or distribution of your muscle and adiposity [accumulation of fat], rather than the absolute weight, may be more important for your health,” Dr. Xu added.
A New Focus on Preventing Alzheimer’s and Parkinson’s
The study serves as a reminder that obesity’s effects on health are complex and multifaceted. While losing excess weight is important, this research suggests that where fat is stored and the amount of muscle mass a person has are equally, if not more, crucial in reducing the risk of neurodegenerative diseases.
As the global population ages and diseases like Alzheimer’s and Parkinson’s become more prevalent, understanding the role of body composition in disease prevention is critical. This research provides a new lens through which to view obesity-related health risks and offers hope that lifestyle changes focusing on muscle strength and fat distribution could play a key role in mitigating the impact of these devastating conditions.
The findings not only raise awareness about the importance of body composition but also suggest that targeted interventions aimed at building muscle and reducing central obesity could one day become part of a comprehensive strategy to prevent or delay the onset of neurodegenerative diseases.