Across the world, the prevalence of MS is increasing, and so is the prevalence of obesity.

Some scientists believe that there is a causal link between these two facts, and that the rise in obesity is driving up MS prevalence, particularly in the Western World.

There are several ways in which being overweight can affect MS. Obesity can increase your risk of getting MS, make your MS symptoms more severe and harder to deal with, trigger more frequent relapses and also accelerate the progression of MS towards increasing disability. By being aware of your weight and taking steps to stay healthy, you are making a real difference to your MS. 

The Body Mass Index (or BMI) is a way of seeing if your weight is appropriate for your height. The actual calculation is your weight (in kilograms) divided by your height (in metres) squared but it's also easy to read on the BMI chart. BMI can be divided into several categories and generally the higher your BMI, the greater your risk of a large range of medical problems, including MS.

BMI categories
BMI Category
Less than 18.5 Underweight
18.5 - 24.9 Healthy weight
25 - 29.9 Overweight
Over 30 Obese

Although this is inaccurate if you are very muscular, it is useful for getting a general sense of whether your weight is within a healthy range. Most BMI charts are only designed for adults, and are not appropriate for women who are pregnant or breastfeeding, or for people who are very frail. 

Obesity and MS risk

Several studies have shown an increased risk of developing MS if you are obese, particularly if you are obese in childhood or early adulthood. One 2016 study found that moving from being 'overweight' (BMI>25) to being 'obese' (BMI>30) resulted in a 41% increase in risk of developing MS.

Researchers have identified a handful of genes associated with obesity that are also associated with MS. This means that if you are genetically more likely to become obese, you are also more susceptible to MS. Some of the increased risk may be related to how your body deals with Epstein-Barr virus (EBV) infection if you are overweight. EBV infection is independently a potential cause of MS, as is smoking and a deficiency in vitamin D.

The link between childhood obesity and MS is particularly strong in girls. This may relate to overweight girls tending to go through puberty earlier, and having higher levels of hormones around that time. Another theory is that excess fatty tissue stimulates inflammation and enhances the likelihood that MS will develop. Fatty tissue also tends to make vitamin D less available in the body, although the effect of obesity on MS risk is not explained solely by vitamin D deficiency.

If there is MS in your family, then you would be advised to make sure that you and your children maintain a healthy weight, get plenty of vitamin D and avoid smoking.

Obesity and MS symptoms

Obesity makes some MS symptoms worse and also puts you at increased risk of developing other conditions unrelated to your MS. This is called co-morbidity, and results in a complex health situation that is harder to treat and more difficult to live with.

People with MS who are overweight are more likely to have higher scores on a EDSS assessment of disability. This works both ways, of course. Having a high EDSS implies reduced mobility, and it can be harder to get effective exercise, while being relatively easy to eat more than you need for your activity levels.

Bladder problems are made worse by being overweight. Excess weight puts pressure on your pelvic floor and can result in stress incontinence.

Pain is also made worse by obesity. If your pain has a musculoskeletal cause, then losing weight may help relieve stress on your body. Losing weight has been shown to reduce pain symptoms in MS, including nerve pain.

For many people, being overweight or obese can interact with their mood and emotions. Feelings of shame, stigma or worthlessness can make it hard to feel positive about life with MS, and hard to stick to healthy habits. On the other hand, if you can find support and make healthier lifestyle choices, you may find your general outlook improving.

If you would like to reduce your weight, talk to your GP or MS Nurse about accessing support for weight loss. You can also look at our tips for diet and exercise, or look at the NHS Healthy Weight website and join their12 week plan.

Obesity and MS progression

Obesity is associated with a higher relapse rate, faster disease progression and increased disability in people with MS at all ages.

Many people with MS look to special diets to help them manage their MS. Although the specific components of their diet may have benefits, one benefit of most special diets for MS is healthy weight management. Maintaining a healthy weight reduces relapse risk and is associated with lower scores of disability. 

The connections between obesity and MS progression are currently being researched. It is thought that fatty tissue in the body may release excess hormones that put the body into a generally inflammatory state, promoting nerve damage and interfering with repair. Excess weight can also put stress on the muscles and skeleton, and lead to the accumulation of disability beyond that caused by MS.

However, obesity, pain and low mood can form a vicious cycle that is hard to get away from. If pain or depression are acting as barriers to exercise and weight loss, or you find you are eating for emotional comfort, do seek help to break the cycle. Ask a friend to encourage and support your goals, and seek effective treatment for pain, anxiety or depression.

Find out more

Mokry LE et al.
Obesity and Multiple Sclerosis: A Mendelian Randomization Study.
PLoS Med. 2016 Jun 28;13(6):e1002053
Full article (link is external)
Langer-Gould A, et al.
Childhood obesity and risk of pediatric multiple sclerosis and clinically isolated syndrome
Neurology. 2013 Feb 5; 80(6): 548–552
Full article (link is external)
Hedstrom, AK, et al.
Obesity interacts with infectious mononucleosis in risk of multiple sclerosis
Eur J Neurol. 2015 Mar; 22(3): 578–584.
Full article (link is external)
Gianfrancesco MA and Barcellos MF
Obesity and Multiple Sclerosis Susceptibility: A Review
J Neurol Neuromedicine. 2016; 1(7): 1–5.
Full article (link is external)
de Jesús Guerrero-García J, et al.
Multiple Sclerosis and Obesity: Possible Roles of Adipokines
Mediators Inflamm. 2016; 2016: 4036232.
Full article (link is external)
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