I recently did some research on the connection between obesity and chronic pain, with a focus on whether weight loss is an effective treatment for pain. Here is a short summary of my conclusions, followed by a longer series of quotes and key findings from relevant studies:
Obesity is significant risk factor for many different forms of chronic pain, including osteoarthritis, pain in non-weight bearing parts of the body, headaches, and neuropathic pain.
Obesity might directly contribute to chronic pain by either increasing mechanical stress on weight-bearing joints, or by increasing systemic inflammation.
Obesity might indirectly contribute to chronic pain by increasing depression, insomnia, and sedentary behavior.
Weight loss has been shown to reduce a variety of chronic pains. The effect size seems to be small to moderate, but this is just as effective as most other treatments, including exercise and physical therapy.
Losing weight is hard, and keeping it off is harder. Weight loss is even harder in the presence of pain, because it tends to lower mood, prevent sleep, and discourage physical activity.
The major takeaway: trying to lose weight is hard, but it is a reasonable strategy for treating chronic pain.
The above facts are consistent with an important theme that emerges from study of chronic pain treatment: interventions that target general health, such as physical activity levels, weight loss, sleep, mental stress, and substance-abuse are often just as effective as interventions that target specific musculoskeletal pathologies.
Let me repeat that:
chronic pain interventions that target general health, such as physical activity levels, weight loss, sleep, mental stress, and substance-abuse are often just as effective as interventions that target specific musculoskeletal pathologies.
Of course most obese people already know that weight loss will improve their health, and have probably heard this a million times before. So we should not assume that education about the connection between obesity and pain will cause immediate weight loss.
On the other hand, weight loss education often focuses on health benefits in the future, and involves reducing risk for diseases that might never occur. Perhaps learning that weight loss could improve life right now would be motivating for at least some people.
Following is a list of relevant papers with key quotes and findings. These will clarify some of the details, ambiguities, and conflicts in the evidence supporting the above conclusions.
The association between chronic pain and obesity (2015)
Link here. Numerous lines of evidence show that obesity increases the risk for chronic pain:
the likelihood of morbidly obese people having a pain complaint was four times higher than those who were not obese. The prevalence of low back pain increases as BMI rises … Relative to normal weight people, overweight people reported 20% greater rates of recurring pain, and the rates go up to 68% for people with class I obesity, 136% for people with class II obesity, and 254% for people with morbid obesity.
Severe obesity in the elderly doubles the likelihood of having chronic pain. A systematic review concludes that obese people are at a greater risk of having headaches, particularly chronic headaches. Similarly, obesity appears to be a risk factor for developing abdominal pain, pelvic pain, and neuropathic pain.
Longitudinal studies also suggest that obesity may be a risk factor for developing chronic pain … .
Chronic pain can also contribute to obesity:
Chronic pain is one of the major reasons that obese patients list for their weight gain … Other common adverse effects of chronic pain, such as sedentary lifestyle, poor sleep, and side effects of medications, may also contribute to weight gain in chronic pain patient
Potential mechanisms underlying the obesity–pain link include mechanical stress on weight-bearing joints, as well as systemic inflammation:
Adipose tissue is … metabolically active, serving as an endocrine organ to produce and release proinflammatory cytokines and adipokins … obesity may be characterized by a low-grade chronic inflammatory state as reflected by elevated levels in many inflammatory markers in the serum … Macrophage accumulation in adipose tissues has also been demonstrated in obese humans, which is known to play an important role in production and release of inflammatory mediators. Thus, obesity can be considered to reflect systemic inflammation which may contribute to pain.
The connection between obesity and pain may be mediated by depression and insomnia:
High prevalence of depression has been well documented both in pain and obesity …, one study showed diminished association between obesity and chronic pain when depression was adjusted for, suggesting the potential importance of depression in impacting the relationship between obesity and pain.
…
Estimated 53% of chronic pain patients attending pain clinics have clinically significant insomnia, significantly greater than 3% in sex-and age-matched healthy people. Conversely, over 40% of insomniacs in the community complain of at least one chronic pain problem.
…
One of the common sleep disturbances in obesity is obstructive sleep apnea (OSA). The strong relationship between obesity and OSA is well documented, and the majority of those with OSA are obese.
Weight loss through dieting or surgery helps with chronic pain:
An early longitudinal observation study of approximately 800 women estimated that the risk of developing knee OA can be reduced by 50% if a person loses 5 kg. Similarly Larsson found that following a weight loss dieting program, people lost on average 14% of their pretreatment weight and that their reports of musculoskeletal pain significantly improved. Vincent et al reported a case–control study in which 25 morbidly obese people who underwent bariatric surgery were compared to 20 sex- and weight-matched controls (ie, no surgery). On average, the patients in the surgery group lost 19.4 kg and 5.2% of body fat at the 3-month follow-up. They also reported significant reduction in pain in the low back and knee, whereas control subjects who did not receive the surgery did not report change in their pain levels.
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A case series observation reports significantly reduced headache frequency and related disability following bariatric surgery. … Khoueir et al followed 38 morbidly obese people with a history of chronic back pain undergoing bariatric surgery … The Visual Analog Scale (VAS) pain scores for low back were 5.2 at preoperative and 2.9 at postoperative. At the year of follow-up, 68% of the patients reported improvement in pain.
Nonsurgical weight management programs, although they generally produce much less weight loss than surgery, also show strong beneficial effects on chronic pain. Multiple reports show that weight management programs involving diet and exercise help OA patients lose weight and improve their symptoms …
weight loss appears to help people with diffuse, generalized pain as well … a 3-month vegan diet open trial resulted in significant weight loss and symptomatic improvement, but both weight and symptoms returned to the baseline after participants resumed a regular diet.
Obesity and Chronic Pain: Systematic Review of Prevalence and Implications for Pain Practice (2015)
Link here.
On the link between pain and obesity:
Although older studies did not substantiate a link, recent and larger studies point toward a possible association between obesity and pain. One study showed that almost 40% of obese individuals suffered from chronic pain, with the prevalence increasing proportionally with BMI … Another large survey of more than 1 million individuals showed that overweight individuals had about 20% more pain compared with normal-weight people, obese individuals with BMIs of 30 to 34 kg/m2 had about 68% more pain, those with BMIs of 35 to 39 kg/m2 had 136% more pain, and those whose BMIs were more than 40 kg/m2 reported having 254% more pain. A study of more than 3000 twins showed that after adjusting for age, sex, and the presence of depression, overweight and obese twins were more likely to report chronic wide- spread pain, low-back pain, tension-type or migraine headaches, abdominal pain, and fibromyalgia than the control group of normal-weight twins.
A review of the evidence that weight loss helps with fibromyalgia in obese patients:
Weight reduction in obese patients with fibromyalgia led to a major improvement in the HRQL. Depression, sleep quality, and tender point count in obese patients with this difficult-to-treat condition have improved considerably with weight loss. These and other authors suggested that a weight reduction program should be a standard part of the treatment protocol for obese individuals with fibromyalgia. Other researchers suggested that pain management intervention should precede the participation of obese individuals in weight reduction programs.
Weight loss has also been proposed as a treatment for headaches:
Although obesity is not a proven factor in successful migraine treatment, some have hypothesized that weight loss could be a feasible approach for alleviating headaches in obese individuals. A recent systematic review suggested that “clinicians should have a special interest for weight reduction” of obese patients with migraines.
Weight loss for upper and lower-extremity pain:
Numerous systematic reviews and high-quality RCTs in patients with OA have documented the benefit of physical rehabilitation on both weight loss and OA status. … Another RCT demonstrated that simple advice on dieting, repeated a few times a year, worked well for both pain control and weight reduction.
Comprehensive treatment of chronic knee pain due to OA was most effective with weight reduction according to 1 systematic review. Dietary intervention plus strengthening exercises seems to be both clinically effective and cost-effective for individuals with knee pain.
The evidence does not support the idea that weight loss is effective for low back pain.
Surprisingly, despite numerous reports of the benefit of weight reduction on OA-associated pain and a significant associ- ation of obesity and low-back pain, weight reduction strategies have not been successful in obese patients with low-back pain. Another recently published study showed that a physical rehabilitation program was effective independently of BMI status in patients with persistent low-back pain. Obese patients had overall worse outcomes from both surgical and nonoperative management of lumbar disk herniation. One Korean study showed that obesity did not affect surgical outcomes following lumbar microdiscectomy. In at least 1 study, investigators suggested this may be due to patient noncompliance.
Influence of weight loss on musculoskeletal pain: Potential short-term relevance (2010)
Link here.
This study found that weight loss helped with musculoskeletal pain:
The study objective was to investigate the relationship between weight loss and changes in musculoskeletal pain … During a 12-week prospective study, the pain ratings in 9 body regions were measured during the bi-weekly weigh-ins at the clinic.
…
A significant association was found between weight loss and reduction of pain in the elbow, upper back, lower back, and hip regions as well as overall pain.
Improvement in the Spatial Distribution of Pain, Somatic Symptoms, and Depression After a Weight Loss Intervention (2017)
Link here. The study examined the effect of a calorie-restriction weight loss plan on pain and inflammation in 123 obese subjects. It found that:
The spatial distribution of pain, fatigue, and depressive symptoms improved.
Improvement was greatest in those losing 10% or more of their body weight.
The anti-inflammatory cytokine interleukin-10 increased after weight loss.
Chronic pain and weight regain in a lifestyle modification trial (2012)
Link here. This study found that people with chronic pain lost less weight and were more likely to regain weight in a weight loss trial.
This study evaluated body weight, physical activity, and diet outcomes in participants with and without chronic pain in a 2‐year behavioral weight loss trial …
Participants with chronic pain lost ∼33% less weight over 2 years, which was driven by greater weight regain after the first 6 months.
Lose Pain, Lose Weight, and Lose Both: A Cohort Study of Patients with Chronic Pain and Obesity Using a National Quality Registry (2021)
Link here. This study found that pain treatment increased weight loss.
A significant reduction of pain intensity was found after [pain treatment]. A similar proportion of patients in the three groups with different pain relief levels had clinically significant weight loss (20.2%~24.3%, p = 0.47). Significant improvements were reported regarding physical activity behaviour, psychological distress, and HRQoL, but weight change was not associated with changes of pain intensity.
Thanks, Todd, great summary, and very useful for me. As usual, it’s like we have the same writing to-do list. 🙂
I should probably add weight loss to my official list of "what works." Difficult and not miraculous… but actually efficacious, the real deal. I think I may have been distracted from that helpful truth by my focus on back pain, where weight loss is (as you noted) surprisingly ineffective. But back pain isn't the only chronic pain!
"Perhaps learning that weight loss could improve life right now would be motivating for at least some people."
Probably, because there are probably people who don't know this yet.
But, as one who does know, I don't find knowing motivating *right now*, since I also know that appropriate medical care aids weight loss. And, like many, I'm behind on appropriate medical care since COVID, and, given residual strain on our healthcare system, wondering if the smart move is just to get used to a permanently lower standard of medical care. I don't see myself as some unfortunate outlier, but rather as a fairly ordinary (even lucky!) example of life with chronic illness in post-COVID America.
My family "runs fat", but through diet and exercise, I maintained a high-normal (often ~24) BMI (with << 30" waist) most of my life, despite connective-tissue glitches and severe asthma. My fitness relied on palliation I had to forego during pregnancy, though, and which hasn't resumed since COVID. I lost the weight after my first baby, but not after my COVID baby.
For example, before this year's ragweed season, I was losing weight and gaining fitness, but right now I'm mostly confined indoors and sometimes bedridden with asthma, though not with attacks bad enough to bet on Urgent or Emergency Care fast-tracking care. No surprise I'm deconditioning and just threw my back out, too. So far, telehealth is better in theory than in practice. Anyhow, I must schedule in-person visits for testing during windows when I can afford to stop medication, without having BigHospCorp cancel on me, as they do more often since COVID. (Or exit BigHospCorp's care altogether, but finding other, affordable providers accepting new patients post-COVID is daunting.)
I *know* that my inflammation (both asthma and pain) is likely worse now *because* of added weight (though some gnarly infections helped). But with flaring asthma (and small kids), the exercise and healthier "slow food" I used to use seem out of reach. I feel guilty about my overweight, but also like I can no longer rely on medical providers to meet me halfway on fitness, almost as if "They don't care, so why should I?" (I don't *logically* believe that. Logically, I *know* less-reliable medical access makes weight loss *even more important*. But my "lizard brain" believes it: "Lizard brain" motivation is easy mode; an unmotivated "lizard brain" sets motivation to hard.)