Obesity and Headache
Obesity has been called the most common disease in America, although technically I believe dental decay holds that distinction.
A BMI (Body Mass Index) of 30 or more places an individual at risk for new onset of chronic daily headaches, which is a condition called New Daily Persistent Headache. A BMI of 25 to 30 is considered "overweight." A BMI of 30 to 35 is called class I obesity, 35-40 is class II obesity, and BMI over 40 is class III obesity. Most of the studies that determined a correlation between obesity and migraine also did so at a BMI of 30 or greater, although the most risk was seen for class II obese women of reproductive age. Neither the prevalence of migraine nor the risk of severe headache were increased in older women or men with total obesity or abdominal obesity.
The Cause and Effect of Obesity—Are Chronic Headaches Included?
From the decade of the 1960s to the decade of the 1970s, medical epidemiologists, the folks who study statistics about diseases, found that the number of people with headaches, and especially migraines, was increasing. But they didn't know why. Now, it may partly be due to increased stress in our lives. And it may partly be that migraines are being diagnosed more. However, the increasing waistlines of the US may also be contributing to an increase in headache severity. There may a correlation between migraine and both total body obesity and abdominal obesity.
There is emerging evidence to suggest that there may be a correlation between metabolic syndrome and migraine as well. An increased waist-to-hip ratio is one of the diagnostic criteria for metabolic syndrome. Interestingly, there was also an increased rate of headache in the underweight. The best BMI in order to avoid headache is 20. What has not yet been determined is whether there are shared genetic factors that place a given individual at risk for both migraine and obesity, or whether something about migraine and the neurochemical changes that go on in the brain predispose toward obesity.
Studies on Obesity, Migraine, and Other Headaches
In 2002, Dr. Dawn Marcus noted that pro-inflammatory chemicals called cytokines had been discovered in migraine, and that they had been found to be elevated in obesity. She conducted a small pilot study (61 headache patients) to look for a relationship between obesity and migraine. She found that obesity was related to headache impact on a validated test of pain severity, psychological distress, and quality of life. The test scores were significantly higher in obese patients. Medical geneticists are currently hard at work to see whether there is a genetic link between migraine, obesity, hyperlipidemia (elevated cholesterol and other blood fats), high blood pressure (hypertension), and other chronic conditions.
Research on obesity is moving forward to look at many complex biochemical relationships to learn more. In 2003, a large study was completed looking at the various risk factors for the development of chronic daily headache. Some things we already knew about or suspected, like medication overuse, or not sleeping. But an association with weight was a surprise to headache specialists. This study, conducted by Dr. Ann Scher and colleagues, involved just over 1,100 people who were followed for a year. The obese people were far more likely to develop chronic daily headache (not acute migraine) than the normal group. Chronic daily headache is defined as headaches which occur 15 days a month or more.
Who is Affected by Obesity and Headache?
In a more recent study, Dr. Marcelo Bigal, interviewed over 143,000 people in order to identify nearly 1,100 with chronic daily headache. Sixty-four per cent of the study population was female. Obese individuals, those with a body mass index (BMI) of 30 or more, were about twice as likely to develop chronic daily headache, 7% vs. 3.8% for the normal group. The group who were just in the overweight range, those with a BMI between 25 and 29.9, had a 5% risk of developing chornic daily headache. Obese middle-aged women were at greatest risk. The obese group were also more likely to miss work due to their headaches. When asked if they had missed more than four days of work, 33% of the obese group answered yes, as compared to 27% of the overweight group and 26% of the underweight group.
Can Weight Loss Help Chronic Headache?
We are not yet know certain to what extent weight management might reduce the frequency and severity of headaches. Some headache specialists feel that this may be so, while others simply suspect that the same risk factors that contribute to obesity also contribute to headache. Further, if you have chronic headaches, you are less likely to be active or to exercise. A recent study of severely morbidly obese patients who underwent bariatric surgery revealed a 50% reduction in the number of headache days after surgery. Reduction of migraine severity was also seen. However, this was a small study, and given the significant risks associated with bariatric surgery, it cannot be recommended for migraine management alone.
The positive finding Dr. Bigal's study is that obese chronic daily headache sufferers were just as responsive to treatment as were other patients. In a second study, Dr. Bigal and his colleagues compared the treatment outcomes of 170 migraine patients. They found that after three months of treatment, response rates were about the same in all weight classes. So, the good news is that whether obesity is the chicken or the egg in chronic daily headache, treatment strategies are still effective.