How do you define normal weight? What about healthy weight?

Eric Robinson, from the University of Liverpool, UK, proposed the visual normalization theory to explain that (i) evaluations about weight status are made relative to visual body weight norms, and (ii) visual body weight norms are shaped by the size of bodies a person is frequently exposed to in their environment.

It’s an appealing concept, and a logical one.

Roughly 70% of Americans are overweight or obese; yet, 60% of these men and 28% of these women think they are the right weight. Not surprisingly, women are more critical of their own weight than men are.

Among those who know they are overweight, a good portion of them underestimate the extent of their fatness — nearly half of obese men and a quarter of obese women consider themselves slightly overweight. The remainder used the term very overweight. If you let people have the option of self-selecting obese for their current weight status, less than 10% of obese adults will.

It’s not just self-perceptions that are off; we also suck at identifying the weight status of others. Roughly half of the parents with overweight or obese kids thought their kids were normal weight. Doctors have been found to correctly identify the weight status of only 20–30% of overweight patients and 50–65% of obese patients, which may explain why 74% of overweight and 29% of obese individuals never receive a diagnosis of overweight or obesity.

In another study, men and women were asked to classify numerous body images by weight status. Men considered healthy and normal weights to be anything up to a BMI of 30, overweight to start at a BMI of 32, and obesity to not begin until a BMI of 37. Women were not much different, believing overweight started at a BMI of 30 and obesity starting at a BMI of 37.

The participants of this study were mostly overweight (26%) or obese (45%). Correlation analyses suggested that, in general, individuals with greater BMIs selected larger bodies as healthy, normal weight, and overweight than their lower weight peers.

Societal conditioning

Can we really blame them, though? After all, normal is common. If common shifts, so does normal. As society becomes fatter, our perceptions of what is a normal weight will also increase.

For example, westerners from the UK perceive fatter bodies as less healthy and fertile compared to the South African Zulu. The Zulus who moved to the UK, however, change their perceptions to be more in-line with the westerners, suggesting that our perceptions are malleable and dependent on environmental and cultural conditions.

Experimental studies support these observations. One such study reported that self-perceived weight status was associated with the weight status of others around them, especially those that were perceived as being slim. Providing participants with bogus feedback about how their bodyweight compared with others of the same gender, ethnicity, and age successfully changed how the participants perceived their own weight.

A person’s internal representation of what constitutes a ‘normal’‐sized body is likely to be shaped by the types of bodies they frequently encounter, so as obesity becomes more prevalent, perceptions of a ‘normal’ sized body will become larger.

Eric Robinson. Obes Sci Pract. 2017 Mar; 3(1): 36–43.

Another study confirmed these findings. Namely, visual exposure to obesity shifted the range of body sizes perceived as being normal upwards. There is also experimental evidence indicating that visual exposure to heavier bodies may increase underestimation of weight status and result in greater visual preference for larger bodies.

Role of the media

It’s notable that all the above findings hold true considering that there is a clear discrepancy between the body types we are exposed to in the media versus everyday life.

Agenda-setting theory illustrates how mass media are instrumental in setting the public agenda, determining the issues to which people are exposed, and what information they receive about those issues. The mass media reflect, reinforce, and shape common culture, including health-related beliefs and behaviors.

One way that mass media could influence public understandings and perceptions of obesity is by contributing to its normalization. People suck as recognizing the weight status of others, remember? Well, that applies to the media too.

Media folk frequently describe images of overweight or obese people as of lesser weight than they truly are, influencing the perceptions of the general public. In fact, the media tends to use images of people with BMIs above 37 to illustrate simple obesity, giving the impression to many obese people that they may not actually be obese.

Summing up

We need to stop normalizing overweight and obesity. Yes, these are the most common weight statuses in the Western world, but that does not mean they should become the norm. The health detriments of being too fat are well established, and that needs to be made clear.

People are far more likely to pursue lifestyle changes to lose weight when they perceive themselves, or receive a doctor diagnosis, as overweight or obese. So, let’s get self-perceptions back on track.