New study: Internalised weight stigma linked to metabolic syndrome

Title: Association between weight bias internalization and metabolic syndrome among treatment-seeking individuals with obesity

Authors: Pearl, Wadden, Hopkins, Shaw, Hayes, Bakizada, Alfaris, Chao, Pinkasavage, Berkowitz, Alamuddin

Source: Obesity (2017) Vol 25, pp 317–322. Link to article

Super-quick summary: High-weight individuals who internalise weight stigma (devalue themselves because of their weight) are at increased risk of metabolic syndrome compared with those who don’t think less of themselves because of their weight.

In more detail:

What they did

Metabolic syndrome is a name given to a group of risk factors, that together, increase the likelihood of conditions like heart disease and diabetes.  This study looked at whether internalised weight stigma (IWS), that is, believing the negative stereotypes about higher-weight people, applying them to yourself, and devaluing yourself because of it, was associated with a higher risk of  developing metabolic syndrome.

The study included 159 ‘obese’ people who wanted to lose weight and volunteered for a randomised controlled weight-loss study. The study was predominantly female (88%) and two-thirds classified their race/ethnicity as Black or African-American. The average age was 44 years old. Participants had their weight, height, waist circumference, blood pressure, HDL cholesterol, fasting blood glucose, and blood triglycerides measured at baseline.  Participants also completed questionnaire measures of depressive symptoms and internalised weight stigma. Average BMI was 41.1, and about a third (32.1%) met the criteria for a diagnosis of metabolic syndrome.*

What they found

• Internalised weight stigma:
  • IWS was generally low in this sample. The questions take the form, for example, “I hate myself for being overweight.” Participants answers can range from 1 (strongly disagree) to 7 (strongly agree), so the midpoint (neither agree nor disagree) is 4. The average was 3.6 (SD 1.1), so tending to disagree with the self-stigma beliefs. When they analysed the results by race, they found that Black participants (who made up 2/3 of the sample) had much lower scores (average 3.4) than White participants (average 4.2 – just over the midpoint).
  • Higher IWS was associated with more depressive symptoms (r=.38, p<.001).
  • Age, sex, and BMI were not significantly linked to IWS scores. That is, older/younger people, men and women, and higher/lower BMIs (although all participants had BMIs over 30 to start with) had similar scores.
• Metabolic syndrome:
  • After controlling for the effect of BMI and depressive symptoms, they found that higher IWS was linked to a 41% greater likelihood of having metabolic syndrome (p=.042).
  • But when they added participant demographics (age, sex, race/ethnicity) into the mix, the relationship between IWS and metabolic syndrome just failed to reach statistical significance, although there was still a 46% increased risk (p=.052).
• Individual cardiometabolic risk factors:
  • As well as looking at a metabolic syndrome diagnosis (3 or more symptoms), they also looked at the relationships between IWS and each individual risk factor.
  • Higher IWS scores were significantly linked to having high blood triglycerides (or taking medications that controlled high triglycerides) and low levels of HDL (good) cholesterol, but wasn’t significantly linked to having high blood pressure, high blood glucose, or high waist circumference. After controlling for all the possible confounds (age, sex, race, depression, and BMI), these relationships were no longer statistically significant.
  • Given the overall low IWS scores and limited range of scores, it can be difficult to pick up big (statistically significant) differences, so they split the sample into three: low scorers, middle scorers, and high scores, then compared how likely the high scorers were to have each risk factor compared with the low scorers. They found that high scorers were over five times as likely to have high triglycerides (and over two and a half times as likely to have metabolic syndrome) as low scorers, and these relationships remained significant after controlling for age, sex, race, BMI, and depressive symptoms. The other risk factors weren’t significantly different in high versus low IWS participants.

What it means 

Most simply, it means that simply devaluing yourself because of your weight increases the likelihood that you’ll have irregular (high) blood triglycerides and makes you more likely to have metabolic syndrome. In other words, it’s not just weight that matters; our feelings about our bodies may affect how healthy they are and increase our risk of metabolic health problems. The fact that stronger relationships weren’t found with blood glucose and depression could be that people with severe depression and diabetes weren’t included in the study, so levels were lower here than they might be in the general population. It is worth nothing, though, that this study was cross-sectional. That means it only looked at people at one point in time. This means we can’t say that IWS causes metabolic syndrome. It could be that people with metabolic syndrome develop higher levels of IWS, or even that something else is causing both of these things. Only longitudinal studies that follow people over time can answer these types of questions.

Other studies looking at IWS have linked higher levels to poorer psychological health (e.g. this one and this one) and health-related quality of life. Not many studies have looked at IWS and physical health, but quite a few have looked at experiencing weight stigma from other people – that is, being treated badly or discriminated against because of your weight, and they have found links between experienced stigma and stress hormones, how our bodies handle glucose, poorer physical and mental health, and even mortality, above and beyond any effects of having a higher BMI. We also know that experiencing weight stigma tends to lead to higher levels of IWS in many people, so IWS may be one of the links between discrimination and poor health. The effects of IWS also seem to be stronger than those of experienced stigma.

These findings are consistent with studies looking at weight dissatisfaction, rather than IWS per se. Being unhappy about your weight has been linked to worse mental and physical health in general, but also to greater risk of having high blood pressure, diabetes, and high cholesterol, elevated inflammatory proteins in the blood, and metabolic syndrome. In my opinion, one of the most exciting findings, though, is this: in a study that followed nearly 10,000 adults for an average of five years, those who were dissatisfied with their weight had three times the risk of developing type 2 diabetes over the follow-up period, compared with those who were satisfied with their weight, even after controlling for BMI! But even better news, those who started off unhappy about their weight, but who were no longer in the dissatisfied group at follow-up, had no increased risk of developing diabetes compared with people who were satisfied the whole time. Together, all of these studies suggest that hating our bodies, no matter what they look like, isn’t good for us. If you do, it might be worth trying something new.

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*Presence of metabolic syndrome was defined as having three or more of the following: waist circumference ≥ 40 inches for men or 35 inches for women; systolic/diastolic blood pressure ≥ 130/85 mm Hg or taking hypertension medication; triglycerides ≥ 150 mg/dL or taking dyslipidemia medication; fasting blood glucose ≥ 100 mg/dL or pre-diabetes medication (people with diabetes were excluded from the study); or HDL (good) cholesterol < 40/50 mg/dL for men/women.