Obesity and overweight are defined as abnormal or excessive fat accumulation that may endanger health.
Obesity rates have more than doubled since 1980 worldwide, according to the World Health Organization. In 2014, more than 1.9 billion adults (39 percent of the world’s population 18 years or older) were overweight, and more than 600 million (13 percent) were obese. In addition, 41 million children were classified as overweight or obese in 2014.
Most of the world’s population live in countries where being overweight or obesity kills more people than being underweight.
Although not much research has been done on the impact of obesity in MS, evidence suggesting that it may contribute to the incidence of MS is growing. Scientists also believe obesity may worsen MS in people who already have the disease.
Obesity may contribute to MS in different ways:
- it contributes to vitamin D deficiency, which plays a role in MS by promoting myelin repair;
- it contributes to chronic low-grade inflammation and release of cytokines that influence immune response;
- it is the most common cause of insulin resistance, metabolic syndrome and diabetes, which are associated with chronic inflammation;
- it increases the risk of disability in people with MS by increasing heart disease, hypertension and high cholesterol;
- It increases obstructive sleep apnea, which contributes to fatigue in people with MS;
- It increases depression.
MS and obesity research
A ground-breaking Canadian study has found evidence for a causal role of obesity in multiple sclerosis. The study, is one of the largest of its kind, found that an elevated body mass index (BMI) — equivalent to an adult average woman going from 150 to 180 pounds — may increase the risk of developing MS by as much as 40 percent.
To study the possible causal link between obesity and multiple sclerosis, researchers used a Mandelian randomization method, which involves the use of genetic variants as instrumental variables to measure exposures to a risk factor on an outcome. They identified 70 genetic predictors of weight and analyzed obesity-related genes in more than 300,000 people. They examined these gene variations in 14,000 people diagnosed with MS and 24,000 people without MS. Researchers found that a genetically determined change in BMI or an increase in BMI caused by other factors increases MS susceptibility.
Even though the researchers provide evidence for a link between obesity and MS, the exact mechanisms that may explain the role of elevated BMI in increasing one’s risk of developing MS remain unclear. Numerous observational studies examining these mechanisms have been conducted in the past. For example, researchers have found that elevated BMI promotes a pro-inflammatory state which affects the immune system and increases the risk of developing MS.
Several factors are known to mediate this mechanism. Notably, adipose-derived hormones or adipokines (hormones secreted by the fat tissue) play an important role. These adipokines modulate inflammation and can be either pro-inflammatory (causing inflammation) or anti-inflammatory (blocking inflammation). Pro-inflammatory adipokines are released uncontrollably in obese people. These adipokines were found to facilitate the development of neurodegenerative changes and thereby increase the risk of developing MS.
It has been demonstrated that adipose-derived hormones such as the pro-inflammatory leptin and anti-inflammatory adiponectin may be associated with MS and MS-related disability. For example, in obese people, high levels of leptin and low levels of adiponectin lead to lower production of regulatory T cells and anti-inflammatory cytokines. These factors potentially increase the risk of developing MS and MS-related disabilities.
Even though these observational studies provide a novel insight into explaining the link between elevated BMI and increased risk of MS, the specific details of the underlying mechanism remain uncertain and must be investigated through a detailed study that examines the role of obesity in the pathogenesis of MS.
Possible ways to prevent obesity
Overeating can worsen MS symptoms such as fatigue, pressure sores, negative self-image, stress on joints, heart and lungs overload, and risk of other illnesses. In addition, certain medications as well as fatigue and depression can lead to people with MS gaining extra weight. Ways to lose weight or maintain a healthy weight include:
- consuming only one meal at a time;
- eating healthy snacks to control one’s appetite;
- concentrating on the food by eliminating distractions while eating, such as smartphones, TV or reading. Tasting and savoring the meal will keep you focused on the diet;
- exercising every day;
- asking for help by joining support groups with similar objectives;
- setting incentives to reach those objectives.
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