Chronic pain is extremely common, affecting up to 20% of the European population, and 13% of Irish people (Raftery et al., 2011). Chronic pain can be debilitating and can hugely affect an individual’s quality of life. In addition to crushing your spirit, chronic pain can also influence our eating behaviour.

Chronic Pain: Overview

Chronic pain is defined as “pain that persists past normal healing time” (Treede et al., 2015), and generally is accepted as pain that occurs for more than 3-6 months. Chronic pain obviously exists on a spectrum, and can be caused by a whole host of things – from musculoskeletal injuries, inflammatory disease processes to gynaecological conditions (Elliot et al., 1999).

Regardless of the cause, chronic pain is not anything to be sniffed at, and can hugely impact the daily life and psychological health of the individual.

Consequently, this huge variation in aetiology makes it difficult to generalise the impact of chronic pain on the individual. Rather, as chronic pain can wax and wane in length, intensity and impact on an individual (Treede et al., 2015), we are better off considering the chronic pain sufferer on a case by case basis. This itself can hugely affect the eating behaviours of an individual.

Why Chronic Pain & Eating Behaviour Matter

When it comes to chronic pain and eating behaviour, researchers tend to focus on the links between chronic pain and obesity. Because obviously, the only thing worse than chronic pain that impairs your ability to live a normal life is getting fat. Priorities, mate.

Of course, we cannot ignore the facts. There is a relationship between obesity and chronic pain. Obese individuals tend to have elevated chronic pain rates as a host of systematic reviews show (Narouze and Souzdalnitski, 2015, Qian, Shi & Yu, 2021). Indeed, obesity may also exacerbate certain chronic pain conditions. For example, excess bodyweight may further stress joints and tissues, elevating inflammation and pain (Okifuji and Hare, 2015).

However, the relationship between obesity and chronic pain is bidirectional. Chronic pain can also contribute to behaviours that lead to obesity, such as emotional or binge-eating (Janke et al., 2007). So it’s a bit of a chicken/egg scenario, but herein lies my annoyance with the research. When we focus on these behaviours purely as pathological from a weight-gain perspective, we miss the forest for the trees.

In my opinion, it’s actually quite ignorant. Just because you’re obese doesn’t mean it’s the reason you have chronic pain, or why it’s so severe for you. Nor does it mean you “deserve” chronic pain.

There is no weight threshold for chronic pain.

Just because studies show that losing weight can reduce chronic pain (Narouze and Souzdalnitski, 2015) doesn’t mean it’s the panacea for all your ailments. And what of those individuals with chronic pain who aren’t obese that engage in disordered eating patterns to cope with their condition? Do we dismiss their plight because they’re not obese?

Obese or not, disordered eating habits occur, and they can really fuck with your head and your life. These behaviours can have a huge impact on depression, anxiety, social behaviours and mental health, and whether they lead to obesity or not shouldn’t be the focus, in my opinion.

The relationship between chronic pain itself and eating behaviour isn’t clean cut, but it certainly warrants us digging a lil deeper.

n=1: Chronic Pain & Me

You didn’t think I would miss an opportunity to make this all about me again, did you?

Chronic pain is shit. And that’s putting it lightly. Chronic pain has been one of the most psychologically challenging experiences of my life. I have experienced chronic pain roughly for over a year now, when one of my lumbar discs sequestered down onto some of my spinal nerve roots. With this came an onslaught of sciatica, which brought radicular leg pain and spasms that varied from a dull annoyance to all-consuming pain.

There were times where a simple sneeze would make my spine feel like it was going to come out my arse (stunning visual, you’re welcome), and spasm out for days. Walking beyond a normal pace would again lead to this radicular pain. And then for good measure, sometimes I would just wake up in a hoop.

It’s not even the physical pain itself that presents the biggest issue. It’s the constant mental energy I have to expend thinking about how to do a simple task like picking something up off the ground. It’s smuggling Difene into festivals like the Peru 2. Or, when things aren’t that bad, it’s the worry that things will get bad again. And then when things are bad, and stuff flares up, you worry you’ll be stuck like this forever.

It’s a lot to process, and I have the utmost respect for anyone that’s been suffering with chronic pain for years, because up until my discectomy in February, I thought I was going to lose my mind from all of this shit. Thankfully, Big Pharma & Modern Medicine came through, and my discectomy has hugely improved my quality of life.

All of this got me thinking about chronic pain and eating behaviour, because I started to notice some trends. Sometimes, during a flare up, I’d become so anxious about the future and my health, it’d completely kill my appetite for days. Other times, I would get so frustrated at my situation that I would rage eat Doritos. And because my n=1 experience means fuck all, it was time for me to get into the literature and see if my experience matches what science says.

Emotional Regulation, Emotional Eating & Chronic Pain

Many studies have shown that chronic pain sufferers engage in comfort or emotional eating. Of course, as per, the majority of research focuses on obese individuals with chronic pain (Amy and Tozak, 2012), (Masheb et al., 2020). However, O’Loughlin and Newton-John (2019) found that up to 75% of chronic pain sufferers emotionally eat, regardless of their Body Mass Index.

So, we shockingly can’t just blame everything on obesity. It is more than likely the emotional disturbances and stress associated with chronic pain that leads to these emotional eating episodes.

Chronic pain is hella dark and can be extremely depressing at times. Depression is unfortunately common in chronic pain sufferers. In a 2012 qualitative study, interviews with chronic pain sufferers revealed that depression hugely impacted their eating behaviours. Depression as a consequence of pain typically leads sufferers to self-soothe with food.

Emotional eating is particularly common during flare-ups of any kind of chronic pain condition. And whilst research has demonstrated this emotional eating to occur regardless of an individual’s BMI status (O’Loughlin and Newton-John, 2019), individuals often report in engaging in overconsumption of hyperpalatable, less nutrient dense foods during these episodes. The intensity of the flare up seems to correlate with a bigger drive to overeat (Janke and Kozak, 2012).

Pain is a stressor, and stress impairs our natural emotional regulation. Pain also drives anxiety and catastrophic thinking, which again leads to emotional regulation impairment (Janke et al., 2016).

Interestingly, chronic pain sufferers share a lot of characteristics with eating disorder sufferers. These include impaired regulation of pain sensations, sensory disturbances, thought/feeling processing and crucially, the hypothalamic-pituitary-adrenal axis (Sim et al., 2019).

The HPA axis largely governs our response to stress and challenge, and altering this can hugely affect our tolerance to stress (Kudielka and Kirschbaum, 2004). These biological disruptions to our natural resilience mechanism cannot be overlooked, and can be a key driver of alteration in eating behaviour in chronic pain sufferers. We cannot ascribe these changes simply to obesity or weight gain, as they occur across all weight classifications.

Disruption in Activity Levels

Expending energy throughout the day, or being active, creates an energy demand in the body. However, when you have chronic pain, daily physical activity can be a challenge.

Flare-ups can reduce even the most active individuals to sedentarism. Pain in response to physical activity can be a huge barrier for chronic pain sufferers (Janke and and Kozak, 2012). Physical activity is generally recommended for chronic pain sufferers, as it can help with inflammation and pain tolerance (Mior, 2001).

However there can be many challenges to its implementation. Chronic pain can lead to individuals falling into a “pain/avoidance” thought process, whereby individuals fear certain movements will exacerbate or initiate a chronic pain flare up (Geneen et al., 2017). Once again, drawing on my n=1 experience, I can attest to this. Once I had my injury, there were certain activities I had to avoid. Too much walking would lead to a flare up, but I wouldn’t feel it straight away. Consequently, I didn’t spend as much time walking as I potentially could have, because the risk of flare up simply wasn’t worth it. I also was partial to a run, but it was too much axial loading for my delicate lady spine, so it was off the cards.

What did this mean for me? My appetite eventually down-regulated, because I wasn’t maintaining my pre-injury levels of activity. For me this lead to some non-intentional weight loss, simply because I wasn’t in need of that much energy any more. Conversely, for others, this reduction in physical activity can lead to weight gain. For some, regular physical activity is associated with better appetite regulation and satiety signalling (Hopkins, King and Blundell, 2010). To suddenly lose that may lead to alterations in energy intake.

So, overall, the impact of alterations in physical activity can be twofold: reducing the biological demand for energy (reducing appetite) and impaired emotional regulation (fear/avoidance from activity). Again, can we attribute this solely to obesity? NO (promise I’ll stop flogging this obesity thing soon).

Big Pharma & Appetite

Here we go. Listen, I love big pharma as much as the next chronic pain hun. Difene is the most stable long-term relationship I’ve ever had. However, whilst pharmacological interventions allow the chronic pain sufferer to have some form of normal life, they can also affect appetite.

Opioids are commonly given to patients to help reduce pain. Things like NSAIDs (non-steroidal anti-inflammatory drugs) provide effective pain relief for many conditions and patients (Rausch and Jansen, 2012). However, opioid use can lead to a litany of gastro-intestinal symptoms that affect appetite, such as bloating, reflux, constipation and nausea (Leppert, 2012). That’s not to say that you shouldn’t take painkillers, dear God follow your doctor’s advice and don’t cancel me, but it is certainly worth noting as an influencing factor on appetite and eating behaviour in chronic pain sufferers.

It is also pertinent to consider this on an individual basis. Certain flare ups can be managed conservatively, and sometimes individuals may need a little more big pharma. So, this GI interference may not be a constant for chronic pain sufferers. Which again, WE CANNOT ASCRIBE SOLELY TO OBESITY *deep breath*.

Conclusions

Chronic pain is a powerful influence on eating behaviour. Huge variation in symptoms, intensity and duration of pain between individuals make it hugely important to consider the individual on a case-by-case basis. Indeed, when it comes to the individual we can almost afford to consider chronic pain on a flare-up by flare-up basis.

Hopefully, by the end of this, I have belaboured the importance of considering chronic pain and as an influence on health and quality of life of an individual as a stand-alone factor, not merely as an addendum to an individual’s BMI status.

If you have any other thoughts on this, or want to fight me on obesity and chronic pain, please let me know!

References

• Elliott, A.M., Smith, B.H., Penny, K.I., Smith, W.C., Chambers, W.A. (1999) ‘The epidemiology of chronic pain in the community’, The Lancet, 354, pp. 1248-1252.
• Geneen, L.J., Moore, R.A., Clarke, C., Martin, D., Colvin, L.A., Smith, B. (2017) ‘Physical activity and exercise for chronic pain in adults: an overview of Cochrane Reviews’, Cochrane Database of Systematic Reviews, 1(1).
• Hopkins, M., King, N.A., Blundell, J.E. (2010) ‘Acute and long-term effects of exercise on appetite control: is there any benefit for weight control?’. Current Opinion in Clinical Nutrition and Metabolic Care, 13(6), pp. 635-640.
• Janke, E.A. Jones, E., Hopkins, C.M., Ruggieri, M., Hruska, A. (2016) ‘Catastrophizing and anxiety sensitivity mediate the relationship between persistent pain and emotional eating’, Appetite, 103, pp. 64-71.
• Janke, E.A., Jones, E., Hopkins, C.M., Ruggieri, M., Hruska, A. (2016) ‘Catastrophizing and anxiety sensitivity mediate the relationship between persistent pain and emotional eating’, Appetite, 103, pp. 64-71.
• Janke, E.A., Kozak, A.T. (2012) ‘”The More Pain I Have, The More I Want to Eat”: Obesity in the Context of Chronic Pain’, Obesity, 20(10), pp. 2027-2034.
• Kudielka, B.M., Kirschbaum, C. (2004) ‘Sex differences in HPA axis responses to stress: a review’, Biological Psychology, 69, pp. 113-132.
• Leppert, W. (2012) ‘The impact of opiod analgesics on the gastrointensitinal tract function and the current management possiblities’, Contemporary Oncology, 16(2), pp. 125-131.
• Mashebm R.M., Douglas, M.E., Kutz, A.M., Marsh, A.G., Driscoll, M. (2020) ‘Emotional Overeating Questionnaire in weight-loss seeking patients’, Journal of Behavioural Medicine, 43, pp. 479-486.
• Mior, S.D. (2001) ‘Exercise in the Treatment of Chronic Pain’, Clinical Journal of Pain, 17(4), pp. 77-85.
• Narouze, S., Souzdalnitski, D. (2015) ‘Obesity and Chronic Pain: Systematic Review of Prevalence and Implications for Pain Practice’, Regional Anesthesia & Pain Medicine, 40, pp. 91-111.
• O’Loughlin, I., Newton-John, T.R. (2019) ‘’Dis-comfort eating’: An investigation into the use of food as a coping strategy for the management of chronic’, Appetite, 140, pp. 288-297.
• Okifuji, A., Hare, B. (2015) ‘The association between chronic pain and obesity’, Journal of Pain Research, 8(1), pp. 399-408.
• Qian, M., Shi, Y., Yu, M. (2021) ‘The association between obesity and chronic pain among community-dwelling older adults: a systematic review and meta-analysis’, Geriatric Nursing, 42(1), pp. 8-15.
• Raftery, M.N., Sarma, K., Murphy, A.W., De la Harpe, D., Normand, C., McGuire, B.E. (2011) ‘Chronic pain the Republic of Ireland – Community prevalence, psychosocial profile and predictors of pain-related disability: Results from the Prevalence, Impact and Cost of Chronic Pain (PRIME) study, Part 1’, Pain, 152(5), pp. 1096-1103.
• Rausch, T., Jansen, T. (2012) ‘Gastrointestinal Side Effects of Opiod Analgesics’, Gastroenterology, 37(12), pp. 36-39.
• Sim, L., Harbeck-Weber, C., Harrison, T., Peterson, C. (2019) ‘Central Sensitization in Chronic Pain and Eating Disorders: A Potential Shared Pathogenesis’, Journal of Clinical Psychology in Medical Settings, 1(1).
• Treede, R., Rief, W., Barke, A., Aziz, Q., Bennett, M.I., Benoliel, R., Cohen, M., Evers, S., Finnerup, N.B., First, M.B., Giamberardino, M.A., Kaasa, S., Kosek, E., Lavand’homme, P., Nicholas, M., Perrot, S., Scholz, J., Schug, S., Smith, B.H., Svensson, P., Vlaeyen, J.W., Wang, S. (2015) ‘A classification of chronic pain for ICD-11’, Pain, 156(6), pp. 1003-1007.