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We’ve all done the zipper dance. You wiggle around the room, holding your breath and inching up your too-tight jeans until they fasten. If you have Multiple Sclerosis (MS), then watching your weight could do more than just helping you fit into your favorite skinnies. That’s because increasing evidence suggests there’s a link between obesity and MS.

So first, what do we mean by obesity? Let’s start by calculating your body mass index, or BMI. This is the measurement doctors use to determine if your weight is healthy for your height. To work out yours, simply divide your weight in kilograms, by your height in meters, squared (i.e. multiplied by itself).

For example, if you weigh 65kg and you’re 1.68 meters tall, your BMI would be 65 divided by (1.68x1.68), which equals 23. (Alternatively, if you hate math, you could just type in your height and weight here!)

Anything between 18.5 and 25 is considered healthy. Between 25 and 30 and you’re considered overweight. Above 30 unfortunately you’re considered obese. Gah. Now here’s why it matters1.

Obesity and MS risk

Being obese isn’t great for your health for a number of reasons. Doctors have always known that carrying excess fat puts a strain on your heart, for example. Increasingly, though, researchers are discovering being obese also causes a number of biochemical changes that can seriously affect your health in the long term.

One of these changes involves levels of a chemical messenger called leptin that plays a role in the regulation of appetite2. As well as telling you when you’re full, leptin is also a cytokine, an inflammatory compound that can affect the immune system3. A recent study found women with MS who were obese had increased levels of the hormone leptin. What’s more, being obese was associated with an increased risk of developing MS – in fact, women, who were obese at age 20 were twice as likely to develop MS later in life than those who were not obese. The researchers suggested this link may be explained by the fact leptin promotes inflammatory responses in the body4. With levels of obesity on the rise, this may also help to explain why the incidence of MS appears to be increasing.

It’s also likely being overweight could affect the course of your MS. Another recent study found people with progressive forms of the disease had higher levels of leptin than those who did not have MS, or those who had a relapsing form of the disease. Again, the researchers suggested a link between leptin levels and inflammation being a factor5.

Another possible explanation for the link between obesity and MS risk is that obesity appears to lower levels of vitamin D6. There is evidence lower levels of this so-called sunshine vitamin are linked to an increased risk of MS, and moreover, a Finnish study also found vitamin D levels were lower during relapses7. So that’s one more very good reason to take your weight seriously. Vitamin D can also be lowered by other factors, such as smoking.

Whatever the link between obesity and MS, it’s a good idea to keep your weight in check by eating a healthy, balanced diet and taking regularexercise.  Of course, keeping fit is easier said than done when you have a chronic condition like MS. Energy levels may be an issue – around 75% of people with MS experience fatigue at some stage in their illness8. The key is to find an activity you enjoy, whether that’s walking, swimming, dancing or gardening, and to do it regularly at a comfortable pace. Yes, getting your trainers on might be the last thing you feel like doing when you’re already exhausted, but research shows regular exercise can actually improve your energy levels and mood – so it’s a win–win!

If you’re concerned about your weight, speak to your doctor about devising a realistic weight-loss plan.


  1. Website “National Heart, Lung & Blood Institute” – Calculate Your Body Mass Index. Available at:
  2. Website “WebMD” – Your 'Hunger Hormones'. Available at:
  3. Leptin in immunology. Matarese G, Moschos S, Mantzoros CS. J Immunol. 2005 Mar 15;174(6):3137-42.
  4. Body Mass Index and Multiple Sclerosis Risk. The Role of Leptin. Jorge Correale, María Eugenia Balbuena Aguirre, et al. Neurology April 8, 2014 vol. 82 no. 10 Supplement S24.004.
  5. Leptin serum levels in different subtypes of Multiple sclerosis: does leptin play a role in progress of Multiple sclerosis? Sayyed Hamid Zarkesh-Esfahani, Ehsan Bahrami, Amir Hadi Maghzi, Masoud Etemadifar, Mohammad Kardi. The Journal of Immunology, 2011, 186, 44.9. Available at:
  6. Causal relationship between obesity and vitamin D status: bi-directional Mendelian randomization analysis of multiple cohorts. Vimaleswaran KS et al. PLoS Med. 2013;10(2):e1001383. Available at:
  7. 25-Hydroxyvitamin D levels in serum at the onset of multiple sclerosis. Soilu-Hänninen M, Airas L, Mononen I, Heikkilä A, et al. 2005 Jun;11(3):266-71. Available at:
  8. Website “Cleveland Clinic” – Fatigue & Multiple Sclerosis. Available at:
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