Migraines have a comprehensive list of risk factors that can elicit an attack. One of the less commonly thought of causes is body mass index (BMI). BMI is a numerical value that is derived from the body mass and height of an individual through an established mathematical calculation. It is an attempt to quantify the amount of muscle, fat, and bone in an individual, and then categorize that person as underweight, normal weight, overweight, or obese based on that value.

Over the past two decades, researchers have discovered that the chances of having migraine are increased in those who are obese (BMI > 30). They have also learned that migraine patients who are obese are more likely to develop a chronic attack pattern.

The link between migraine and BMI has been analyzed for over 15 years, with more than a dozen studies conducted on patients of all ages and types. Examining macroscopically, the evidence says that individuals with a BMI greater than 30 raises the risk of having migraine as much as 50%. Yet the risk grows as obesity increases, and it’s almost 3-fold (275%) in patients with BMIs above 40.

Understanding the relationship

Fat is a highly active substance. In fact, fat secretes a wide range of molecules that send signals to other bodily systems. For obese individuals, the extra fat cells induce the body to make inflammatory proteins. Therefore, obesity keeps the body in a mild, yet constant, state of inflammation.

It is not yet fully understood how migraines and body composition are related, but studies are underway. Factors such as changes in physical activity, medications, or other conditions such as depression may play a role in the relationship between migraine and body composition. Hypothalamus (area of the brain responsible for hunger) and neurotransmitters associated with migraine may also be responsible.

What about a low BMI?

Recently, there were some tentative findings in which individuals who were underweight (BMI less than 18.5) were more likely to suffer from a migraine attack. Twelve studies on migraine and BMI involving nearly 300,000 people were examined. Underweight individuals were 13 percent more likely to have a migraine than people of normal weight. Still, more relevant research is needed to determine whether efforts to help people gain weight could lower their risk for migraine.