Maintaining a healthy weight could cut MS risk, study finds
A higher BMI increases odds of developing MS by about 40%

People genetically prone to a higher body mass index (BMI) are also more likely to develop multiple sclerosis (MS), a study finds.
The findings confirm an association between being overweight or obese and a higher likelihood of developing MS, and suggest that lifestyle changes to maintain a healthy weight may serve as a way to reduce the risk of MS. BMI is a measure that’s based on height and weight, and is commonly used as an indirect indicator of body fat.
The study, “Genetic Association and Causal Effects Between Obesity and Multiple Sclerosis: A Robust Two-Sample Mendelian Randomization Study,” was published in Cureus.
The exact causes and mechanisms of MS aren’t fully understood, but several factors are thought to contribute to how it develops, how fast it progresses, and how severe it is. One such factor is excess weight. Obesity, defined as having a BMI higher than 30, can lead to chronic inflammation in the body, setting the stage for developing MS. Obesity can also make MS symptoms more severe and increase the changes of severe disability in patients.
People who are severely obese in childhood or adolescence are more likely to develop MS. This suggests that “weight management in early life may serve as a preventive strategy against MS,” wrote Abdulaziz Almosallam, a researcher at Majmaah University in Saudi Arabia and the study’s author.
BMI and MS risk
To better understand this relationship, Almosallam used Mendelian randomization, a method that draws on genetic data to determine if there is a causal link between an exposure — in this case, being overweight or obese — and an outcome (developing MS) without interference from outside factors such as diet and nutrition.
The study used two sets of data from a public database. The first set included 461,460 people of European ancestry and was used to identify which single nucleotide polymorphisms (SNPs) — that is, change in a single letter in a DNA sequence, the most common type of mutation — are linked to higher BMI.
The second set of data, from the International MS Genetics Consortium, came from 115,803 people from Europe and provided information on which SNPs were linked to MS. By combining the two sets of data, Almosallam could estimate if genetic variations linked to higher BMI were also associated with a greater MS risk.
A total of 323 SNPs were included, with the findings showing a higher BMI increased the odds of developing MS by about 40%.
“These findings support and reinforce previous observational studies suggesting that obesity, especially during adolescence and early adulthood, may elevate the risk of MS,” Almosallam wrote. “Ongoing education about the impact of BMI on MS should be promoted in both clinical settings and patient outreach programs. Engaging patients in discussions about how body weight can influence their disease can empower them to actively participate in managing their health.”