A Guide to Size Diversity 

Bodies come in all shapes and sizes, with everything from genetics to family history and environment playing a role in how we look. But sadly, in many cultures—and especially Western cultures—that same body diversity is not widely reflected in popular media or even sometimes in medical research.

Reviewed By | Michelle Ervin, MEd

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The result is a system of beliefs, often internalized, about what “healthy” or “desirable” bodies should look like. And this can have a detrimental effect on mental health, including self-esteem and body image. In America alone, almost 80% of people in one poll reported feeling unhappy with how their bodies look at times.1

Yet the reality is that there is no one “superior” body shape or size. Health can come at any size, and people of all body shapes and weights should be celebrated for the unique and beautiful traits they bring to the world. Those are some lessons about size diversity.

Almost 80% of Americans report feeling unhappy with how their bodies look at times.1

The practice involves accepting all bodies—including our own—as worthy of love and respect. And while it can be difficult to deprogram often lifetimes of toxic or unhelpful messaging around physical appearance, health, beauty, and desirability, learning more about body diversity can be an important first step toward a healthier outlook.

Body Size and Discrimination 

We all have bodies composed of the same materials: bone, muscle, and fat. Our bodies should be as familiar to us as the sound of our voices. Still, it’s easy to internalize the voices around us, which all have different opinions on what constitutes health and beauty, often influenced by the unrealistic images in pop culture and unhealthy messages of toxic diet culture.

We may also have thoughts and feelings about how others look, which, consciously or not, can be influenced by the weight bias commonly hidden in popular culture. We may actively judge others by denying them jobs, refusing to date them, or bullying them due to their weight or shape, which can have detrimental effects on their mental health.2 One of the best ways to combat this type of weight discrimination is to understand and examine what common terms used to describe someone’s body weight or shape really mean.

woman in dress

Body Size Diversity and the Body Mass Index

Many ideas about “appropriate” body size and weight, especially in medicine, are tied to the body mass index (BMI).

A chart comparing the average height and weight of adults, the BMI organizes these ratios into weight-based categories, including:

  • Obese
  • Overweight
  • Normal weight
  • Underweight

Though long used as an indicator of general health, the system has come under scrutiny lately. Those opposed to the BMI say it’s not as much of a global indicator of health as it’s been treated, failing to acknowledge important factors like metabolic health.16

The system also tends to gloss over the different ways fat can be distributed in the body—which makes a substantial impact on health—and the various types of body compositions or conditions, including athletes or pregnant women, who may have BMIs outside the “average,” but still be healthy.16

Regardless, this is the number many people look to when classifying someone as “obese,” “overweight,” or “underweight.”

“Overweight” and “Obesity”

Almost 74% of American adults 20 and older are considered “overweight,” and nearly 42% are considered “obese.”3 These labels are based on the body mass index (BMI).

What’s worrying about this statistic is not the number of adults labeled a certain way based on a narrow and imperfect tool but the weight-based discrimination or shaming they’re likely to encounter.

The risk of weight-based discrimination increases drastically with weight, with findings showing:4

  • Overweight women: 10% report discrimination
  • Obese women: 45% report discrimination 

That discrimination can take many forms. For example, people may experience the following:

  • Medical discrimination: Doctors may subconsciously associate larger people with unhealthy people and recommend weight loss or other weight-related solutions rather than treat the symptoms the person is actually experiencing. 
  • Employment discrimination: People in larger bodies are associated with specific characteristics, including laziness, leading to fewer leadership opportunities or promotions. There may be a limit on career advancement.
  • Travel discrimination: Larger people may need to make additional travel accommodations or skip some travel plans altogether due to fear of discrimination. 
  • Overt bullying: Larger people are told they’re fat, lazy, disgusting, or lack self-control. Young children experience this bullying at school and online, but adults can also hear muttered comments at work or the store. 

Some people assume stigmatizing weight will encourage people to lose pounds. Instead, researchers say, this stigma leads to poor physical and mental health.5 Some people deal with stigma by resorting to disordered eating.

woman standing


Skinny, small people often fit into the culture’s idea of an ideal. As a result, they may not face the same type or level of bullying compared to their larger counterparts. Still, they may feel intense pressure to stick to their small size, even when they’re aging, getting pregnant, or facing another issue associated with weight gain.

66% of American fashion models would be considered to have anorexia.6

But being “underweight” or too thin comes with its own costs. Researchers say that 66% of American fashion models who fit our standards of thin beauty have body mass index ratings within the range of anorexia.6 While BMI, weight, and body size are not indicators of health, a weight that is too low can have serious health implications.

Thin people can also get teased to eat food, work out more, or change how they look to make others happier. They may face discrimination and judgment because they are skinny.

Why “Obese,” “Overweight,” and “Underweight” are Arbitrary and Stigmatizing

In fact, “obese,” “overweight,” “underweight,” and also “fat” are themselves discriminatory and judgmental, comparing them to a “normal” ideal that is arbitrary and does not necessarily represent “good” health. All these weight categories are based on BMI, which is not a marker of health, are arbitrary, and have changed over time based on societal norms.7

Instead, an individual’s habits, such as “healthy” eating and exercise, do not greatly impact body size and health. Several other factors, including genetics, environment, and social determinants of health, significantly impact health.8 In addition, body size itself is not an indicator of health. [8] Bodies can be “healthy” at all weights, shapes, and sizes.9 In fact, being classified as “obese” does not have a greater risk of death than those with lower BMIs.10 And there’s increasing evidence that it is actually weight stigma, not weight itself, that can lead to eating disorders and certain health conditions that are frequently misattributed to weight.11

4 Ways to Foster Size Diversity 

Many of us have said or done something to harm another’s body image. It could have come from a conscious decision to cause harm, or it could have come from a place of ignorance. 

No matter the cause, we can all educate ourselves and promise to serve our communities and ourselves better. 

Embracing weight inclusivity means accepting and respecting diversity in body shape and size.12 Rather than believing in a model that celebrates thin and small bodies, we acknowledge that every body is different and no form is better. 

If you’re supporting the thin ideal, take a step back. Examine the media you read, watch, and listen to regularly. Does it represent all body types? Does buying magazines filled with thin models make your community safer for all body shapes? Does reading blogs about the newest diet trends make you feel better within your own skin? Is sharing videos featuring only thin, white, fit people being inclusive of all? Be mindful of the media you consume, share, and create. 

“You look great! Have you lost weight?” We’ve all said or heard it at least once, and it’s not helpful. Training yourself to stop commenting on weight could also help you stop noticing it in others. 

When giving out a compliment, discuss a person’s accomplishments. Better yet, just tell them how much you appreciate them.

Weight fluctuations are remarkably common. For example, boys between ages 4 and 6 can gain or drop up to 4 pounds between daily check-ins.13 

Commenting on someone’s weight fluctuation could spark disordered eating. And you could inflict that damage on someone you care about. 

What if you change your language, but no one around you shifts in return? You can help. 

Culture is pervasive, and seeing our mistakes without outside help is hard. If you hear someone being discriminatory, speak up. Most people don’t understand they’re being hurtful.14

If you’re comfortable, speak up and provide direct feedback. If not, reach out to the person later to discuss what happened.

For example, if someone turns down a coworker’s offer of a cookie by saying, “No thanks! I don’t want to get fat,” you could say the following:

  • In the moment: “Hey, that’s not nice! We all deserve cookies; all bodies are beautiful, regardless of shape and size.”
  • Later on: “Hey, your comment about cookies wasn’t very sensitive. You didn’t notice, but Jane looked upset after you spoke. Talking about your diet can make people feel like they should diet, too.”

It’s hard to open up a dialogue about body positivity and fatphobia. Still, it’s one of the most effective ways to make people think about what they say and deliver real change.

Mend your relationship with your own body.15 Pay attention to how you feel about:

  • Food: Eat when you’re hungry and stop when you feel you’ve had enough. Remember that all foods are okay, and craving something that tastes good is just fine. Food is fuel, not a reward or a punishment.
  • Health: How you feel about your body’s ability to do what you want matters more than an arbitrary size. Celebrate what your body does for you every day. Don’t blame it for how it looks.
Woman working on computer

Get Help When You Need It

For many people, size-based discrimination, weight stigma, and fatphobia lead directly to disordered eating. Many people who struggle with disordered eating may not be aware or may deny they have a problem. 

If you suspect you or someone you love has been using unhealthy techniques to change your appearance, know you can get help. 

Your primary care physician or therapist is a good place to start. These experts can help point you toward successful programs or help you work on your mental and physical health directly.

But the most important thing to remember is that you are so much more than your body weight, shape, or appearance. You are a unique individual, primed to offer the world all the gifts that are special to you, no matter how you look.


  1. Jackson C, Lemay M-P. (February 13, 2018). Most Americans Experience Feeling Dissatisfied With How Their Body Looks from Time to Time, Including Nearly Two in Five Who Feel This Way Whenever They Look in the Mirror. Ipsos. 
  2. Brownell KD, Puhl RM, Schwartz MB, & Rudd L. (2005). Weight bias: Nature, consequences, and remedies. Guilford Publications. 
  3. Obesity and Overweight. (2022). Centers for Disease Control and Prevention. 
  4. Puhl RM and Heuer CA. (2012). The Stigma of Obesity: A Review and Update. Obesity; 17:941-964. 
  5. Hunger JM, Major B, Blodorn A, Miller CT. (2015). Weighed Down by Stigma: How Weight-Based Social Identity Threat Contributes to Weight Gain and Poor Health. Social and Personality Psychology Compass, 9(6):255-268. 
  6. Park S. (2017). Comparison of body composition between fashion models and women in general. Journal of Exercise Nutrition and Biochemistry, 21(4):22-26. 
  7. Nuttall FQ. (2015). Body Mass Index: Obesity, BMI, and Health: A Critical Review. Nutrition Today; 50(3):117–128. 
  8. Dubois L, Ohm Kyvik K, Girard M, Tatone-Tokuda F, Pérusse D, Hjelmborg J, Skytthe A, Rasmussen F, Wright MJ, Lichtenstein P, & Martin NG. (2012). Genetic and environmental contributions to weight, height, and BMI from birth to 19 years of age: An international study of over 12,000 Twin Pairs. PLoS ONE; 7(2). 
  9. Bacon L, & Aphramor L. (2011). Weight science: Evaluating the evidence for a paradigm shift. Nutrition Journal; 10(1). 
  10. Flegal KM, Kit BK, Orpana H, & Graubard BI. (2013). Association of all-cause mortality with overweight and obesity using standard body mass index categories: a systematic review and meta-analysis. JAMA; 309(1):71–82.
  11. Wu Y-K, & Berry DC. (2017). Impact of weight stigma on physiological and psychological health outcomes for overweight and obese adults: A systematic review. Journal of Advanced Nursing; 74(5):1030–1042. 
  12.  About Health at Every Size. (2022). Association for Size Diversity and Health.
  13.  Rao DH, Sastry JG. (1976). Day-to-day variation in body weights of children. Annals of Human Biology; 3(1):75-6.
  14. Lobell KO. (2022). How Some Employers Are Addressing Weight Discrimination. SHRM.
  15.  Body Size Diversity and Acceptance. (1999). University of Illinois. 
  16. Shmerling R. (2023, May 5). How useful is the body mass index (BMI)? Harvard Medical School. Accessed February 2024.

Last Update | 03 - 14 - 2024

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