Association of Weight-Related Stigmas With Daily Pain Symptoms Among Individuals With Obesity

Abstract

Background

Individuals with obesity are disproportionately impacted by pain-related symptoms.

Purpose

This study evaluated experienced weight stigma and internalized weight bias (IWB) as predictors of pain symptoms in daily life among individuals with obesity.

Methods

Adults with obesity (n = 39; 51% female, 67% White, 43.8 ± 11.6 years old, BMI = 36.8 ± 6.7 kg/m²) completed a baseline assessment (demographics, experienced weight stigma, IWB) and a 14-day Ecological Momentary Assessment (EMA) period involving five daily prompts of pain/aches/joint pain, muscle soreness, experienced weight stigma, and IWB. Generalized linear models were used to assess experienced weight stigma and IWB at baseline as prospective predictors of EMA pain/soreness symptoms. Multi-level models were used to test the association of momentary weight stigma experiences and IWB with pain/soreness at the same and subsequent EMA prompts.

Results

IWB at baseline, but not experienced weight stigma, was associated with more frequent pain symptoms (p < .05) and muscle soreness (p < .01) during EMA. Momentary IWB (but not experienced stigma) was associated with more pain/aches/joint pain and muscle soreness at the same and subsequent prompt.

Conclusions

Internalized (but not experienced) weight bias was prospectively associated with pain symptoms in daily life among individuals with obesity. Results are consistent with growing evidence that weight-related stigmas represent psychosocial factors that contribute to weight-related morbidity typically attributed to body size.

Internalized weight bias, but not experienced weight stigma, was prospectively associated with pain symptoms in daily life among individuals with obesity.

Introduction

Obesity is prevalent and remains a major global health concern [1]. Individuals of higher body weight are at increased risk for daily pain and chronic pain conditions [2, 3]. Earlier work focused on biomedical explanations (e.g., mechanical loading on joints) did not completely account for the relationship [4]. Increasingly, models are expanding to incorporate psychological and social contributors consistent with the biopsychosocial perspective of pain [5].

Several cross-sectional studies document an association between weight stigma and pain symptoms among individuals of higher body weight, and in some cases weight stigma statistically mediated the association of BMI with pain symptoms [6–8]. Weight-related stigma is the social devaluation of individuals of higher body weight based on negative stereotyping (e.g., lazy, lacking in self-control; [9]). Individuals might experience negative treatment resulting from weight stigma (i.e., experienced weight stigma), or adopt these negative attributes and believe they are accurate about themselves (i.e., internalized weight bias [IWB]).

Conceptualizing various forms of weight stigma as contributors to pain symptoms is aligned with numerous theoretical models highlighting psychological and social factors in pain phenomenology. Work from social neuropsychology suggests that there may be some degree of overlap in the physiological pathways involved in processing social pain and physical pain [10, 11]. As such, weight-related stigma may contribute to the experience of physical pain by potentiating parts of the physical system involved in sensation and perception of physical pain. Similarly, the Gate Control Theory of pain highlights that top-down processes related to cognition and affect/emotion can modulate the experience of physical pain [12]). Indeed, several reviews substantiate the role of emotion in the experience of pain [13, 14], as well as the symbiotic crosstalk between cognition, affect, pain-related behaviors and pain outcomes (e.g., pain catastrophizing and anxiety are highly comorbid and associated with functional outcomes in the context of pain [15]). Taken together, affective distress associated with social rejection due to body size and internalized negative attitudes could potentiate the pain experience directly by facilitating neural processing of pain input from the peripheral nervous system and indirectly by promoting maladaptive affective and cognitive experiences.

Yet the existing data associating weight-related stigma and internalized weight bias are preliminary and cross-sectional. While weight stigmas may be modifiable risk factors for pain symptoms that should be considered in treatment development, evaluating these relationships with more rigorous observational/longitudinal data is a logical and judicious next step in the translational research continuum. The current study addresses this limitation by using Ecological Momentary Assessment (EMA) data from an existing study to test the following a priori hypotheses: (1) experienced weight stigma and IWB assessed at baseline will prospectively predict pain symptoms assessed via EMA in daily life and (2) experienced weight stigma and IWB assessed at the momentary level will be associated with momentary pain symptoms at concurrent and prospective EMA prompts in daily life.

Subjects and Methods

Participants

This is a secondary analysis of a larger study investigating weight stigma among adults with obesity compared with adults with obesity and HIV. Only adults without HIV were included in the current analysis. Participants were recruited from the community and inclusion criteria included self-reported body mass index (BMI) ≥ 30 kg/m², ≥18 years old, English-speaking, smartphone and internet access. Exclusion criteria included reported history of psychotic disorder(s) (i.e., factors that impair ability to provide informed consent), reported sleeping ≥25% of the time between the 9:00 AM and 9:30 PM EMA assessment window, current pregnancy, history of weight loss surgery, or other factors likely to affect reports of eating behaviors.

Procedures

All study procedures were conducted remotely and approved by the Lifespan Institutional Review Board. Participants completed a baseline assessment followed by a 2-week EMA period using a smartphone app hosted by LifeData [16]. Participants watched an orientation video that explained EMA procedures, defined stigma, and clarified EMA questions with examples. Weight stigma was defined as times when the individual felt like they were perceived differently, treated differently, or singled out by others or the environment because of weight. Participants were given numerous examples of stigmatizing events and were oriented to the specific stigma questions from EMA surveys. At each EMA prompt assessing stigma, participants were given a list of examples (e.g., being harassed or threatened, being glared at or singled out). Participants were prompted to complete entries five times randomly between 9:00AM and 9:30 PM, with prompts occurring ≥2 hours apart. Prompts not answered within 60 minutes of receipt counted as missing data, per standard practice [17].

Baseline Measures

Demographics

Participants self-reported height and weight (used to calculate BMI in kg/m²), gender, age, and race/ethnicity.

Experienced weight stigma

The 10-item Stigmatizing Situations Inventory–Brief (SSI-B; [18]) was used to assess the frequency of lifetime weight stigma events on a scale from 0 (never) to 9 (daily) using one global score.

Internalized weight bias

The 10-item Modified Weight Bias Internalization Scale (WBIS; [19, 20]) assessed the extent to which individuals apply negative societal beliefs about obesity to themselves. Participants report their answers on a scale from 1 (strongly disagree) to 7 (strongly agree). Higher scores reflect greater internalized bias.

Bodily pain

The two-item subscale of the MOS-Short Form-36 (SF-36; [21]) was used to assess presence and interference related to pain symptoms during the previous 4 weeks (“how much bodily pain have you had” and “how much did pain interfere with normal work”). Higher scores reflect lower levels of pain.

Pain conditions

Participants completed a self-report questionnaire to assess various medical conditions (i.e., in the past year, have you experienced or been treated for the following medical conditions). Individuals who endorsed General chronic pain, arthritis, migraine, or neuropathy were coded as having a pain condition.

Pain medication

Participants indicated if they had used Codeine, Vicodin, Oxycontin, or Fentanyl more than once within the past year (yes/no).

The following items were assessed at every prompt using EMA:

1. Pain symptoms. “Since the last entry, have you experienced any of the following?” (1) Physical pain, aches, or joint pain, (2) Muscle soreness with a yes/no response option.

2. Experienced weight stigma. “Have you experienced any stigmatizing events since the last prompt?” with a yes/no response option. Participants who endorsed stigma answered follow-up questions about the stigma event(s) including perceived reason(s). Any report of stigma due to weight was coded as a weight stigma event.

3. Internalized weight bias. Two items assessed IWB: “Since the last prompt…” (1) “I’ve felt anxious about my weight because of what people might think of me.” and (2) “I’ve wished I could drastically change my weight.” Participants responded on a 7-point Likert scale (1 = strongly disagree to 7 = strongly agree). These items were adapted from a widely used trait measure of IWB (WBIS; see above). Item scores were averaged at every prompt to create a mean momentary score.

Data Analytic Strategy

Analyses were conducted in SPSS Statistics 26.0. To assess whether baseline IWB and experienced weight stigma were prospectively associated with total pain symptom frequency in daily life (Aim 1), four non-multilevel generalized linear models (GLMs) examined whether baseline IWB predicted total frequency of physical pain, aches, or joint pain (Model 1) and muscle soreness during EMA (Model 2) and whether baseline experienced weight stigma predicted total frequency of physical pain, aches, or joint pain (Model 3) and muscle soreness during EMA (Model 4). GLMs used a negative binomial distribution and log link function. Pain symptom frequency was computed by summing the total number of EMA prompts where pain symptoms were reported throughout the EMA period. Effect sizes are interpreted as relative risk ratios (RRs), which convey a relative increase in the outcome count for each one unit increase in the independent variable.

Aim 2 examined associations between momentary IWB and experienced weight stigma and momentary reports of physical pain and muscle soreness at the concurrent and prospective EMA prompts. Given the nested structure of the data, eight multi-level generalized linear mixed models (GLMMs) with a random intercept were implemented and the within- and between-person variance in momentary IWB was disaggregated [22]. A time-lagged variable for state weight stigma variables was computed by shifting participant scores at each prompt within a given day to the next prompt time point. To account for binary outcome variables, a binomial distribution with a logit link function was used. Effect sizes are interpreted as odds ratios. Covariates included age, race/ethnicity, gender, education, BMI, baseline pain conditions, use of pain medications, and EMA adherence, and in Aim 2 models, time of day.

Results

Thirty-nine individuals with obesity were included in data analysis (Table 1 includes demographic and descriptive data). A total of 43 participants enrolled; two withdrew during the EMA period due to unanticipated adherence barriers and two did not meet minimum EMA adherence requirements and were excluded from analysis. During the EMA period, participants completed 2,359/2,730 delivered prompts (86%) and 92% of participants met criteria for good adherence (i.e., completing ≥70% of prompts; [23]).

Table 1.

Participant Characteristics

	EMA sample adults with obesity n = 39
Biological sex (%)
Male	49%
Female	51%
Age (M ± SD; range)	43.8 ± 11.6; 18–64
Self-reported BMI (M ± SD; range)	36.8 ± 6.7 kg/m2; 30–60 kg/m2
Race/ethnicity (%)
White, non-Hispanic	67%
Asian	8%
Black/African American/Caribbean	8%
Hispanic/Latino	15%
Other	2%
Sexual orientation (%)
Straight/heterosexual	80%
Gay/lesbian/homosexual	15%
Something else (e.g., bisexual)	3%
Education level (%)
High school or less	15%
Bachelors/associates/some college	49%
Graduate/some graduate	36%
Baseline weight stigmas	Mean ± SD; range
SSI-brief (0–9 scale)	1.8 ± 1.6; 0–6.4
Internalized weight stigma (WBIS)	4.3 ± 1.5; 1–6.5
Pain	Mean ± SD; range
SF-36 Bodily pain Subscale	2.60 ± 1.12 (1–5.5)
Chronic pain	15%
Arthritis	26%
Neuropathy	3%
EMA measures
	% (n = 39) endorsing any	Average number of endorsements*	Range
Physical pain, aches, or joint pain	69%	13.41 ± 20.53	0–65
Muscle soreness	67%	7.56 ± 13.06	0–54
		Mean	Range
Internalized weight bias	100%	4.02 ± 1.37	1.23–6.86
Weight stigma experiences (# events)	33%	0.85 ± 1.87	0–10

*Participants received up to 70 prompts (5 prompts per day for 14 days; e.g., participants reported physical pain, aches, or joint pain at an average of 13.41 prompts out of 70).

As shown in Table 2, higher baseline IWB was associated with more frequent muscle soreness (p < .01) and physical pain, aches, or joint pain (p < .05) over the EMA period. Each incremental increase in IWB was associated with 41–69% more risk for pain symptoms. Baseline experienced weight stigma was not associated with momentary pain symptoms.

Table 2.

Prospective Associations Between Baseline Levels of Lifetime Experienced Weight Stigma and Internalized Weight Bias and Total Frequency of Pain Symptoms During the EMA period among adults with obesity (Aim 1)

	Physical pain/aches/joint pain				Muscle soreness
	B	SE	Wald chi-square	p	B	SE	Wald chi-square	p
Internalized weight bias (WBIS)	0.34	0.14	5.61	.018	0.53	0.15	11.68	<.001
Age	−0.01	0.03	0.03	.866	−0.01	0.03	0.026	.872
BMI	−0.03	0.03	1.26	.261	−0.02	0.03	0.32	.570
Nonprescription pain med. use (ref=none)	2.37	1.01	5.47	.019	1.44	1.05	1.90	.168
Pain condition diagnosis (ref=none)	−2.43	0.56	18.59	< .001	−0.65	0.56	1.38	.240
Sex (ref=female)	−0.24	0.56	0.18	.672	1.02	0.59	2.97	.085
Education (ref: high school or less)	−1.01	0.46	4.83	.028	−0.66	0.38	2.94	.086
Race (ref: White)	−1.82	0.63	8.48	.004	−2.48	0.76	10.64	.001
EMA adherence	0.06	0.03	3.42	.065	0.02	0.03	0.47	.493
Experienced weight stigma (ref = no stigma)	0.24	0.14	2.96	.085	0.11	0.13	0.63	.427
Age	−0.01	0.03	0.05	.827	0.01	0.03	0.05	.828
BMI	−0.04	0.03	1.26	.262	0.02	0.04	0.20	.656
Nonprescription pain med. use (ref = none)	1.89	0.99	3.60	.058	0.60	1.04	0.34	.562
Pain condition diagnosis (ref = none)	−2.20	0.56	15.21	<.001	−0.35	0.57	0.37	.541
Sex (ref = female)	−0.37	0.55	0.45	.502	0.82	0.60	1.85	.173
Education (ref: high school or less)	−0.77	0.48	2.53	.112	−0.46	0.39	1.39	.238
Race (ref: White)	−1.77	0.63	7.95	.005	−2.85	0.78	13.20	<.001
EMA adherence	0.08	0.03	5.42	.020	0.01	0.04	0.02	.892

Notes: ^m p < .10 (marginally significant), *p < .05, **p < .01, ***p < .001. BMI body mass index; EMA Ecological Momentary Assessment; SSI Stigmatizing Situations Inventory.

GLMMs showed that higher levels of momentary IWB were associated with more frequent pain symptoms reported at concurrent and subsequent EMA prompts (see Supplementary Tables 1 and 2). This was a primarily between-subjects effect, suggesting that participants who reported higher momentary levels of IWB during the EMA period, compared with others, were 2.67–2.68 times more likely to report physical pain, aches, and joint pain at the same prompt (b = 0.99, SE = 0.32, OR = 2.68, p < .01) and the subsequent prompt (b = 0.98, SE = 0.33, OR = 3.02, p < .01), and 1.77–1.81 times more likely to report muscle soreness at the same prompt (b = 0.57, SE = 0.29, OR = 1.77, p < .10) and the future prompt (b = 0.59, SE = 0.28, OR = 1.81, p < .05). Furthermore, within-subject effects indicate that elevations in momentary IWB, regardless of one’s overall IWB levels, was associated with 33% greater risk for muscle soreness at the same EMA prompt (b = 0.29, SE = 0.10, OR = 1.33, p < .01), but not with future risk for muscle soreness, or with concurrent or future risk for physical pain, aches, or joint pain. Momentary experienced weight stigma was not associated with concurrent or prospective risk for momentary pain in daily life (p > .05).

Discussion

The current study demonstrates that among a sample of men and women with obesity, individuals who internalize negative weight-related attitudes and stereotypes are more likely to report pain symptoms in their daily lives. This effect was specific to IWB, as no relationship with experienced weight stigma was identified. This is consistent with growing evidence indicating that IWB may be an especially insidious form of weight-related stigma [9, 24, 25].

It is also of note that the association of baseline and momentary IWB with both momentary pain-related measures was significant in models adjusted for BMI, highlighting the association of IWB with pain symptoms above and beyond body size. Consistent with existing literature, post hoc unadjusted analyses indicate BMI was a significant predictor of pain symptoms in daily life in the current sample, even with a range that was restricted to ≥30 kg/m². However, in the fully adjusted models presented, BMI was no longer significant. Conceptually, this highlights the importance of work investigating whether BMI is such a robust predictor of pain resulting from higher adiposity per se, or if there are additional mechanisms that may be important as well.

The current study represents a step forward methodologically for understanding the relationship between weight stigmas and pain. The prospective nature of the current study demonstrates temporal precedence, a necessary step for establishing that IWB (assessed at baseline) causally influences pain (assessed as physical pain, aches, or joint pain as well as muscle soreness in daily life) and not vice versa. Previous literature relied on cross-sectional data and therefore could not determine if weight stigmas were contributing to pain or vice versa. As an additional check, a post hoc GLM analysis of the current data were conducted and revealed that pain levels at baseline did not significantly predict average levels of momentary IWB in daily life.

This study is a small, secondary analysis of a predominantly White sample. All conclusions should be interpreted cautiously with such limitations in mind. Furthermore, BMI was based on self-report data, and pain medication/treatment were not thoroughly assessed. Replication in a larger, representative sample is needed. Additional research is warranted in this area focused on experienced weight stigma as self-report measures like the SSI rely on recall for the entire lifespan which increases vulnerability to recall bias and may not be sensitive to capturing the lived experience of individuals with higher body weight. Furthermore, such measures of experienced weight stigma do not fully account for the larger sociocultural context of living in a society where weight stigma messaging is pervasive (e.g., media), but not likely to be reported as a personal experience. At a minimum, the low report of experienced weight stigma in the current sample may have limited power to test the relationship of experienced weight stigma with pain symptoms.

Despite these limitations, there are strengths of the current study including a longitudinal design that facilitated prospective analyses and use of ecological momentary assessment to investigate pain symptoms in daily life which reduces the risk of recall bias. The current study provides a step forward in the literature suggesting that IWB may be a psychosocial contributor to pain among individuals with obesity. These results coincide with leading perspectives on pain that emphasize a biopsychosocial conceptualization.

Funding

This work was supported by the Dr. George A. Bray Research Scholars Award Fund, Department of Medicine, Warren Alpert Medical School of Brown University; The Miriam Hospital Immunology Center; The Providence/Boston Center for AIDS Research (CFAR; NIH grant P30AI042853); and training grants from the National Heart, Lung, and Blood Institute (T32HL076134), the National Institute on Minority Health and Health Disparities (K23MD015092), and the National Institute of Diabetes and Digestive and Kidney Diseases (K23DK124578).

Compliance with Ethical Standards

Authors’ Statement of Conflict of Interest R.R.W is on the Scientific Advisory Board of NOOM. K.L.O., E.P., and J.L. declare they have no conflict of interest.