Research has shown that the risk of lower back pain increases steadily with weight gain. A research team from Boston University School of Medicine analyzed one year of medical records from over 110,000 patients aged 18 and older who visited hospitals, revealing these findings.
According to the study, in the range of Body Mass Index (BMI) between 18 and 35, the prevalence of lower back pain increases by 7% for each unit increase in BMI. The Body Mass Index (BMI) is calculated by dividing weight (kg) by height squared (㎡), and one unit of BMI corresponds to about 4.5kg of weight based on the average height of adults. In other words, for an adult of average build, the risk of experiencing lower back pain increases by 7% each time their weight increases by about 4-5kg.
The research team conducted the study across a wide range of weight categories, from underweight (BMI 18, around 40kg) to just before severe obesity (BMI 35, around 100kg), and clearly demonstrated the correlation between weight and lower back pain. However, it was found that in the severe obesity range where BMI exceeds 35, the prevalence of lower back pain does not increase further and remains at a certain level.
Lower back pain is a common condition that leads to disability, loss of work, and economic burden. Although the impact of weight gain and Body Mass Index (BMI) increase on lower back pain has not been clearly established until now, this large-scale study has proven a distinct correlation.
The research team stated that medications or physical therapy can help with lower back pain, one of the most commonly reported symptoms by patients, and correcting risk factors such as smoking or decreased physical fitness is also effective. This research result (Body Mass Index and Prevalence of Low Back Pain: Correlation in a Large, Contemporary Cohort) was recently published in the international journal 《Pain Medicine》.
Generally, lower back pain occurs due to mechanical stress on the spine and biochemical changes. When weight increases, the center of gravity shifts forward, disrupting the natural curve of the spine, and the load on the lumbar region and surrounding muscles and ligaments increases sharply. In particular, abdominal obesity is cited as a major cause of chronic pain as it significantly tenses the muscles around the lower back.
Inflammatory substances secreted from adipose tissue also exacerbate pain. Excess body fat promotes the secretion of systemic inflammatory mediators such as cytokines. This can cause minor inflammation around the spinal nerves or accelerate degenerative changes in the discs. Biological factors also act in a complex manner in addition to pressure from weight alone.
Lower back pain ranks first among diseases that cause disability worldwide. According to the results of the Global Burden of Disease Study (GBD 2021) published in the international journal 《The Lancet》, the number of lower back pain patients worldwide was about 619 million in 2020, and it is projected to increase to about 843 million by 2050. The domestic situation is similar. According to recent statistics from the Health Insurance Review and Assessment Service, the number of patients receiving treatment for spinal diseases has steadily increased, with about 1 in 5 people experiencing lower back pain.
Risk factors for lower back pain include not only obesity but also aging, lack of physical activity, smoking, and poor posture. In particular, smoking hinders blood flow to the spinal bones, preventing proper nutrition to the discs and accelerating degeneration. To prevent lower back pain, it is essential to maintain an appropriate weight and correct lifestyle habits, such as regular exercise to strengthen core muscles (trunk muscles) and quitting smoking.
[Frequently Asked Questions]
Q1. Why is it said that the risk of pain increases every time weight increases by 4-5kg?
A1. This is because one unit of Body Mass Index (BMI) analyzed in this study corresponds to about 10 pounds (approximately 4.53kg) when converted to actual body weight. The research team from Boston University confirmed that in the range of BMI 18 to 35, the probability of experiencing lower back pain increases by an average of 7% for each unit increase in weight.
Q2. Why does the risk of pain not increase further when BMI exceeds 35?
A2. In the group with severe obesity (BMI over 35), the prevalence of pain has already reached a peak level, showing a plateau. This is interpreted as the patients in this range already experiencing high levels of pain, so even if their weight increases further, the reporting rate of pain does not increase, or other physical factors besides weight are acting in a complex manner.
Q3. What lifestyle habits should be practiced to reduce lower back pain besides weight loss?
A3. In addition to weight management, it is important to correct risk factors such as smoking. Smoking accelerates disc degeneration by hindering blood flow to the spinal bones, making quitting essential. Additionally, regular physical activity to strengthen the core muscles that support the spine should be combined to distribute the mechanical load on the spine.
