Understanding Body Mass Index On A Deeper Level

Medically reviewed by Andrea Brant, LMHC
Updated May 30, 2024by BetterHelp Editorial Team

If you’ve learned about body mass index (BMI) in health class or at the doctor, you may be curious to find out more about what it is and how it’s used. Though BMI is still a part of many standard doctor’s visits and can serve as a helpful snapshot of one’s body composition, it’s far from an all-encompassing measure of overall health. 

This article will explain how to calculate BMI, its uses and limitations of BMI, tips for maintaining a healthy lifestyle, and considerations for treating issues related to healthy habits and self-image.

Your weight doesn’t have an inverse relationship to your worth

What is body mass index (BMI)?

Body mass index (BMI) is an estimation of body composition based on a person’s height and weight. To calculate BMI, you can divide your weight (in kilograms) over your height (in square meters). However, it’s easiest to use an online calculator to compute BMI. 

The calculator will give you a number which corresponds to one of four categories: underweight, normal weight, overweight, or obese. Generally speaking, a higher BMI indicates more body fat, though there may be some variation due to factors like bone density or muscle mass. Despite being a somewhat simplistic metric, BMI values can provide an easy way to identify whether a person might be at an increased risk for certain health problems related to obesity. 

Extensive health research indicates that excess weight is associated with a higher likelihood of experiencing health complications including cardiovascular disease, diabetes, liver disease, and cancer. In fact, the World Health Organization estimates that nearly 3 million people die each year as a result of being overweight or obese. Thus, weight management can be a crucial aspect of self-care and well-being.

Is BMI an accurate measure?

For most people, BMI can be a worthwhile metric for gauging obesity-related health risks and providing a general sense of where they stand in terms of body weight categories. However, BMI is only one metric, and accurately assessing an individual’s overall health may require a more comprehensive analysis by a medical professional.

Limitations of BMI

While public health authorities such as the Centers for Disease Control (CDC) and National Institute of Health (NIH) still recommend the use of BMI, it is important to be aware of its limitations. BMI does not factor in lean body mass, bone density, or fat distribution, nor does it take into account race, sex, age and other factors that can influence a person’s body composition. 

For example, a person who lifts weights regularly and has higher than average muscle mass may be considered overweight or even obese according to their BMI, although they may have quite a low body fat percentage. Women tend to have more body fat than men at the same BMI, and older adults may have more body fat than younger adults with the same BMI.

For a more accurate estimate of body fat, it may be worth taking some other measurements. Waist circumference, skinfold thickness measurements, and DEXA scans can provide a more nuanced view of body composition. Blood tests and fitness assessments can also give you a more well-rounded understanding of your overall physical health.

Children and teens might need to use a BMI calculator adjusted for age for a more accurate value. Note, however, that rapid growth in a child’s height or weight fluctuations can mean that a healthy BMI may vary somewhat, even for children of the same age. If a child or adolescent has a BMI outside of the healthy range, it may be worth discussing some intervention strategies for identifying and working towards an ideal weight.

Health and worth beyond the scale

A teen boy in a brown shirt and backpack sits outside on a sunny day and smiles at the camera.

If you are considered overweight or obese based on BMI, it is important to remember that a person’s physical health goes far beyond their weight and that there are a wide variety of healthy BMI ranges. If an individual smokes cigarettes, for example, they’re prone to a variety of health risks. If they rarely get exercise, they may be at risk for another set of health complications. A BMI calculator does not evaluate a person for factors like these, which is why it’s generally recommended that you continue conversations with your doctor about your health beyond the number that you see on the scale or the BMI that was calculated.

It’s also important to remember that a person’s value, intelligence, or worth have no correlation with their body fat composition. Even today, people who are viewed as being in the overweight range often face unfair treatment. Bullying, microaggressions, discrimination, and other negative behaviors toward those with larger bodies than what society or the media deem to be average or best are unfortunately common. While the cultural messaging around weight and size can be harsh and harmful, the implications that anyone is less valuable or less worthy of love and respect because of their size are untrue.

Maintaining good physical health

In general, a robust body of research supports a few basic activities that can help keep you healthy at different ages, regardless of your size or body type. These include:

  • Fueling your body with nutrient-dense foods and limiting your intake of processed foods;

  • Staying active with physical activity you enjoy; 

  • Getting plenty of quality sleep each night;

  • Staying hydrated and limiting consumption of sugary drinks; 

  • Finding healthy outlets for managing stress

These activities can not only help with weight management, they can also improve cardiovascular health, enhance mental well-being, strengthen muscles and bones, and increase overall physical and mental resilience. 

One example of supportive research is a ten-year longitudinal study of 2,287 middle and high school students. It found that reducing fast food intake and screen time while increasing fruit/vegetable intake, family meals, and moderate-to-vigorous physical activity resulted in 32% of adolescents exiting the BMI category of “obesity” as they progressed into young adulthood. However, you might be surprised to learn that abstaining from dieting as an adolescent was also associated with exiting the “obesity” BMI category. 

While healthy dietary habits are a good thing, creating harsh restrictions and inflexible rules surrounding food can end up creating more problems. Instead, it may be preferable to aim for balance and nourishment rather than focusing on numbers like weight and BMI. 

Teens and self-image

For teens, BMI may not be the best way to evaluate health because, during the teenage years, a person’s body may change significantly. When thinking about body mass index, teens may experience weight fluctuations, in addition to the physical changes associated with puberty which can make it difficult to use BMI as an accurate representation of health, especially in children. These adjustments can also be challenging to experience, and some may feel insecure as a result. Remember, however, that changes like these are completely normal. While the development of adolescence can be more tumultuous, your body will continue to change over your lifetime.

Cultivating a healthy, accepting relationship with your body can be difficult, however, given the many pressures we’re all exposed to—especially through the media. It’s one reason that disordered eating habits often start during a person’s teenage years. In fact, 95% of people with eating disorders are between ages 12 and 25. Remember that eating disorders are clinical mental health concerns that generally don’t resolve without treatment. If you’re concerned you or your child may have an eating disorder, seeking help is typically important for your well-being. There’s no shame in getting the support you need and deserve for a concern like this, and the right healthcare professional or healthcare provider can help you feel better.

How can therapy help build self-esteem?

A teen girl with a back pack sits in a chair and shakes hands with the woman sitting across from her while smiling.
Getty/SDI Productions
Your weight doesn’t have an inverse relationship to your worth

The way you feel about your body can have a significant impact on how you feel about yourself overall, and even how you’re able to function or enjoy your life day-to-day. If you’re facing concerns or challenges related to your weight or appearance, speaking with a therapist may help. For those who may be experiencing a mental health condition like an eating disorder, a mental health professional can devise the appropriate treatment plan based on the individual’s unique situation. For those who are experiencing low self-esteem or would like support in learning how to practice more positive self-talk, stick to healthier habits, or set boundaries with those who have negative attitudes about their bodies, a therapist can provide support and guidance with these topics as well.

While studies suggest that both online and in-person therapy offer similar benefits, some teenagers may prefer the online format. For those with mental health concerns related to their body, speaking with a mental health professional via phone and/or chat may help them feel more in control of how they’re perceived—especially if they’ve experienced appearance-based discrimination from healthcare providers in the past. In addition, online therapy is often more available and affordable than in-person office visits. 

Research also supports the effectiveness of online therapy in helping people overcome issues with body image. One study suggests that the use of internet-delivered cognitive behavioral therapy for perfectionism (ICBT-P) was effective in helping participants reduce dysmorphic concerns, selective attention abnormalities, body image disturbances, depression, anxiety, stress, and perfectionism. If you’re interested in online therapy, you can get matched with a licensed therapist with your parent’s consent through a virtual therapy platform like TeenCounseling. You can speak with your provider via phone, video call, and/or chat to address your concerns in the way that feels most comfortable for you. 

Counselor reviews

Read on for client reviews of TeenCounseling therapists. “My son has been working with Tara for a few months. She is compassionate, professional, kind, and caring. She takes the time to get to know the person and the family. Her methods are gentle and very well-developed. I would recommend Tara to anyone seeking a good counselor for a teen with generalized anxiety, social anxiety, self-image challenges, and more.”

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While BMI is a measure still recommended by some, many reject it in favor of a more holistic, nuanced approach to health. Compassionate, qualified health professionals—including a licensed therapist—may be able to help you determine more empowering and accurate health markers to help you on your journey toward achieving health and well-being overall. Reach out to a licensed counselor at TeenCounseling or BetterHelp for empathetic, informed support.
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