- Migraine and obesity affect more women than men.
- Age changes the association between headache and obesity.
- In younger individuals, (of childbearing-age), general (total body) obesity or belly obesity increase the risk of episodic headache
- In older populations, total body or belly obesity do not increase headaches and migraine specifically.
- Those with general obesity have a greater prevalence of high frequency migraine (migraines occurring 10-14 days per month) than those without.
- The risk of becoming a chronic daily headache sufferer is greater in those with general obesity and episodic headaches. Risk is lower in those with episodic headache without general obesity.
- The risk of chronic daily headache is greater in those with general obesity than those without.
- Very limited data suggests weight loss and exercise may decrease headache frequency.
Migraine is more likely in women than in men and occurs most commonly in those of younger adult age. In addition, more women are obese than men. Specifically, although the presence of general or total body obesity (often estimated by the body mass index (BMI),) is about equal in both genders (31% of men and 33% of women), more women than men have belly obesity (42% of men and 61% of women). Recent research has shown an association between obesity and migraine in those of younger adult age.
First, in order to understand why migraine may be associated with obesity, it is important to understand how normal fat tissue is distributed and its role in the body. Fat tissue location changes based on a person’s gender and age. Specifically, before menopause women deposit fat in greater quantities than men in the more superficial layer of body fat called subcutaneous adipose tissue. In contrast, perimenopausal and menopausal aged women deposit more fat in the deeper layer of body fat called visceral adipose tissue than younger women. Furthermore, men of all ages have more of the deeper visceral fat than women, with the visceral fat tissue representing 20% of total body fat in men compared to 6% in women.
These gender and age differences are important. The expression of proteins and the function of cells of the fat tissue differ based on whether they reside in the superficial or deep fat layer. Visceral fat tissue produces greater quantities of interleukin-6 (IL-6) than subcutaneous fat tissue. IL-6 is a proinflammatory cytokine which is a small protein released by cells that has specific effects on the interaction, communication or behavior between cells. In contrast, subcutaneous fat tissue produces greater quantities of leptin and adiponectin than visceral fat tissue. These two hormones have roles in feeding and inflammation.
In addition to age and gender differences, how obesity is measured or estimated is important to keep in mind. Excessive fat tissue in relation to fat-free mass results in the state of obesity. Obesity is best estimated by direct imaging of an increase in fat mass to fat-free mass. This can be done with CT or MRI. However, obesity is often indirectly estimated due to cost and practical limitations. Total weight and not just excessive fat often defines obesity. Total weight includes fat mass plus the weight of skin, organs, muscle and bone. A calculation using height and total weight often estimates general or total body obesity. This is known as the body mass index or BMI. You can calculate BMI on the Internet. Whether you calculate BMI using self report of height and weight or measured height and weight is important. Studies have shown that people, including migraineurs, underestimate their weight. Thus the use of self-report of height and weight can lead to under diagnosis of obesity. For example a person with a self-reported BMI of 28.5 will be identified as overweight but when height and weight are measured may actually have a BMI of 30 and fulfill criteria for obesity. Even with these drawbacks the BMI is a valuable tool for tracking large populations where direct measurements are not possible. Another method, waist size, estimates belly obesity. It is not rare for people to have only belly obesity without fulfilling criteria for general obesity based on the BMI. Both, the BMI and waist size estimate can be used to track population changes in obesity in a cost-effective manner.
Studies of Migraine and General & Abdominal Obesity
Multiple studies have evaluated ties between headaches and obesity. These studies have looked at the ties between obesity and episodic headache in general, chronic daily headache and specifically episodic migraine. The first study to evaluate the obesity and headache association showed that those who were obese and had episodic headache had a greater risk of becoming chronic daily headache sufferers than those who were not obese and had episodic headache. Several studies evaluating episodic headache or episodic migraine and obesity then followed. Overall these studies support that either general or belly obesity in those of younger adult age increased headache. Specifically, studies have shown that the risk of migraine or severe headaches increased almost 40% in women with either general or belly obesity and almost 40% increased in men with general obesity and 30% in men with belly obesity as compared to those who are not obese.
Prevalence is a medical term which represents the total number of cases of a disease in a given population at a specific time. Studies support that the prevalence of those with high frequency episodic migraine, (those with migraine headache on 10-14 days of each month,) is higher in those with general obesity estimated based on self-reported BMI. Specifically while only 4.4% of those without general obesity and 5.8% of those who were only overweight had high frequency episodic migraine, 13.6% of those who were obese with a self-reported BMI between 30-to 34.9 and 20.7% of those with severe obesity, (defined as a self-reported BMI of 35 or more,) had high frequency episodic migraine.
Obese older people, including women in menopause or entering menopause, do not have an increase in migraine prevalence. There appears to be no conflict regarding this data. However, questions remain about a connection between episodic migraine and obesity in younger people. Two general population studies found no tie between episodic migraine and obesity when obesity definitions were based on self-report of height and weight. In contrast, two small clinic-based studies and two general population studies have found an increased prevalence of episodic migraine/severe headaches in those with obesity. These latter two general population studies used data from the National Health and Nutrition Examination Survey (NHANES). Specifically, these studies showed an increased prevalence of migraine and severe headaches in those with general and belly obesity. Although the migraine diagnoses in these studies were self-reported as migraine or severe headaches, obesity was estimated using measured height and weight and waist size.
How can we make sense of studies that differ in results? Differences in study design may have contributed to the differing results. Specifically, studies which did not find a connection between obesity and migraine used self-report of height and weight to estimate BMI and obesity. Self report, as stated before, may cause an under-reporting of weight. This may have lead to this lack of connection between migraine and obesity. These studies also included women of peri and post-menopausal age which may also have contributed to the lack of association.
What Should We Believe About Migraine and Obesity
At present, based on the available data, we can confidently say that general or belly obesity increases the prevalence of episodic headache in those of younger adult age. In addition those who are obese and have episodic headache have a greater risk of developing chronic daily headache than those who are not obese. We can also state that obesity may increase the prevalence of high frequency migraine. And finally, there is no evidence of an association between obesity and migraine in older individuals or in those of post-reproductive age. More young adult age studies are needed. These studies should use the International Classification of Headache Disorders criteria to diagnosis migraine and use measured height and weight to estimate obesity. These studies should determine if an association between migraine of any frequency in young adult age and obesity truly exists.
What’s the Link between Migraine and Obesity?
How episodic and chronic daily headache links to obesity is not known. It is likely that pathways which overlap and regulate feeding and migraine play a role. One region of the brain involved in this pathway is the hypothalamus. The hypothalamus participates in the regulation of feeding and becomes activated during acute migraine attacks.
Serotonin and orexin are hypothalamic brain nerve chemicals known to regulate food intake. They appear to have a role in migraine or chronic daily headache. Adiponectin and leptin are predominantly fat cell produced hormones which have receptors in the brain. They have a role in inflammation and also appear to play a role in migraine or chronic daily headache. Further research into the role of these and other obesity-related proteins and chemicals may help us to understand migraine and lead to new treatment strategies.
Limited data exists on the role of weight loss and exercise in the reduction of migraine frequency. However one small pilot study suggests that aerobic exercise may decrease headache frequency, while another small study suggests weight loss with a low fat diet could help decrease headache frequency and intensity. Taken together, this data suggests that those who are obese and have episodic headaches or chronic daily headaches should avoid weight gain. Additionally, the provider and obese patient should consider options for migraine prevention that are not associated with weight gain. Also, the obese patient who suffers with headaches should attempt weight loss. Following these ideas will decrease the risk of obesity related disorders, (such as elevated cholesterol and heart disease,) and could help reduce headache frequency.
Migraine and obesity are common disorders. Both belly and general obesity are shown to be associated with migraine or severe headaches. In addition, obesity increases the likelihood of episodic headache sufferers developing chronic daily headache. The association of obesity to migraine appears due to products produced in the hypothalamus and fat cells. Very limited research suggests weight loss and exercise may decrease headache frequency. As such, weight loss for overall health is a good idea. This may also reduce headache frequency in those migraineurs with either belly or general obesity.
B.L. Peterlin, Director JHU Headache Research, Johns Hopkins Bayview Medical Center, Baltimore, MD.