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Your BMI calculator results: What does it mean?

Classification Under-weight
BMI/Health Index

Your result: Underweight BMI range

Being underweight could be a sign that you are not eating enough or that you may be ill.

Suggested next steps

If you are underweight, contact your healthcare professional for further evaluation.

This BMI calculator is not applicable if you are below 18 years old. BMI is interpreted differently for children and teens, even though it is calculated using the same formula as adult BMI. Please consult with your healthcare provider for BMI information under 18.

Your result:

BMI Classification Table
BMI Classification
Below 18.5 Underweight
18.5 to 24.9 Normal Weight
25 to 29.9 Overweight
30 to 34.9 Obesity Class I
35 to 39.9 Obesity Class II
40 to 49.9 Obesity Class III
50 to 59.9 Obesity Class IV
60 and above Obesity Class V

Cut-offs are different for people of South-, Southeast- or East Asian descent.

This BMI calculator is for adults 18 years or older. Talk to your healthcare professional about your BMI if you're under the age of 18.

Tips and advice for you

Remember, BMI is used as a screening tool; however, if you find yourself in the higher BMI categories, you might want to try some new habits while you are waiting to talk to your healthcare professional. Click on an item below to see what you can do to make a change today.

Nutrition

There is no perfect dietary approach for losing weight. But there are ways of eating that can help you manage weight and prevent the weight from coming back. Whole, unprocessed foods provide the most nutrients and are generally lower in calories. And studies have shown that when presented with ultra-processed food, like soft drinks, ice cream, hot dogs and fries, people tend to consume more calories. So find a way of eating that works for you, while focusing on whole foods and limiting ultra-processed foods as much as possible.

Learn more about starting healthier ways of eating and choosing foods for better weight control here.

Mental health

There are many reasons why we gain and manage weight and sometimes, they have to do with how we feel. 

Some people use food to cope with difficult situations and soothe their feelings. Eating to feel better is called emotional eating—it's the reason why we sometimes need psychological support instead of dietary advice.

Stress can also change the way that you eat and put you at more risk of developing obesity. Learning to manage the stress in your life is one strategy you can also include in your weight management plan.

Note that a side effect of many medications used to treat mental health conditions—like antipsychotics, and antidepressants and stimulants—is weight gain.

If you take medication to treat a mental health condition and have gained weight, discuss the medication’s benefits and side effects with your doctor.

Activity

Regular physical activity is one of the best things you can do for your health, regardless of your weight. To make sure that your obesity weight loss program is as effective as possible, consider adding aerobic and resistance exercises to your routine. Remember that all movement is good movement, and small changes to your routine can make a big difference.

Find tips for getting a good start on a new exercise program here

Sleep

Getting too little sleep can affect your hormones, which can then affect how and what you eat. When you sleep better, you're better able to make healthy choices and resist tempting foods. Try these tips to improve your sleeping habits:

  • Turn off electronic devices (e.g., TV or phone) one hour before bed 

  • Limit or avoid caffeine in the afternoon and evening 

  • Try a calming activity (e.g., a bath or reading) before bed 

Your obesity health risk

Living with overweight or obesity is associated with an increased risk of mortality and other diseases or conditions. Studies have found that generally, the higher your BMI, the greater the risk of developing other chronic obesity-related diseases, including:

  • Type 2 diabetes

  • Cardiovascular disease

  • Stroke

  • High blood pressure

  • Infertility (in women)

  • Depression and anxiety

  • Coronary artery disease

  • Dyslipidemia

  • Metabolic dysfunction-associated steatotic liver disease (MASLD)/Metabolic dysfunction-associated steatohepatitis (MASH)

  • Gastroesophageal reflux disease (GERD)

  • Metabolic syndrome (MetS)

  • Urinary incontinence

  • Obstructive sleep apnea

  • Chronic kidney disease

  • Various types of cancer: including but not limited to breast, colon, endometrial, esophageal, kidney, ovarian and pancreatic cancer

  • Osteoarthritis

  • Gallbladder disease

  • Blood clots

  • Gout

  • Increased risk of mortality compared to those with a healthy BMI

See the health benefits of losing weight.

Why is BMI important to know?

BMI is a good way to screen your risk of excess body fat potential affecting your health. Living with overweight or obesity is associated with an increased risk of mortality and other diseases or conditions. Results from studies show that generally, the higher your BMI, the greater the risk of developing other chronic obesity-related diseases, including:

  • Type 2 diabetes

  • Cardiovascular disease

  • Stroke

  • High blood pressure

  • Infertility (in women) 

  • Depression and anxiety

  • Coronary artery disease

  • Dyslipidemia 

  • Metabolic dysfunction-associated steatotic liver disease (MASLD)/ Metabolic dysfunction-associated steatohepatitis (MASH)

  • Gastroesophageal reflux disease (GERD)

  • Metabolic syndrome (MetS)

  • Urinary incontinence

  • Obstructive sleep apnea

  • Chronic kidney disease

  • Various types of cancer, including but not limited to breast, colon, endometrial, esophageal, kidney, ovarian and pancreatic cancer

  • Osteoarthritis

  • Gallbladder disease

  • Blood clots

  • Gout

  • Increased risk of mortality compared to those with a healthy BMI

Ask your healthcare professional for more information about any of these diseases and how they relate to your BMI. You can also learn more about the health benefits of losing weight here.

What are the limits of BMI?

BMI is a simple and objective measurement, but it can be misleading in certain cases and for some groups of people. Research has shown that BMI is less accurate in predicting the risk of disease in people who are older, athletes, those who are tall or short and those with more muscular body types. For example, elite athletes or bodybuilders have more muscle and weigh more, which makes their BMI higher.

BMI also doesn't take into account:

  • Genetic risk factors associated with obesity-related diseases, such as metabolic syndrome

  • Environmental and lifestyle factors other than obesity that can contribute to your risk of developing chronic disease

  • How body fat is distributed in individuals

It's important to remember that living with obesity doesn't necessarily mean you're unhealthy, just as being at a “normal” weight doesn't mean you're healthy. Your BMI doesn't define you, but knowing and understanding your BMI can be a powerful tool for taking charge of your own health.

Regardless of your BMI, healthcare professionals recommend having a healthy dietary approach and lifestyle. Talk to your healthcare professional about your weight and health and evaluate what actions may be needed. 

References
  1. Rueda-Clausen CF, et al. Canadian Adult Obesity Clinical Practice: Assessment of People Living with Obesity. August 4, 2020. http://obesitycanada.ca/wp-content/uploads/2020/09/6-Obesity-Assessment-v5-with-links.pdf

  2. Guh DP et al, “The incidence of co-morbidities related to obesity and overweight: A systematic review and meta-analysis. BMC Public Health. 2009;9(1):88.

  3. DDağ ZÖ, et al. Impact of obesity on infertility in women. J Turk Ger. Gynecol Assoc. 2015;(2):111-117.

  4. Zhao G, et al. Depression and anxiety among US adults: associations with body mass index. Int J Obes. 2009;33(2):257-266.

  5. Van Hemelrijck M, et al. Longitudinal study of body mass index, dyslipidemia, hyperglycemia, and hypertension in 60,000 men and women in Sweden and Austria. PLoS One. 2018;13(6):e0197830.

  6. Loomis AK, et al. Body Mass Index and Risk of Nonalcoholic Fatty Liver Disease: Two Electronic Health Record Prospective Studies. J Clin Endocrinol Metab. 2016;101(3): 945-952.

  7. Jacobson BC, et al. Association Between Body Mass Index and Gastroesophageal Reflux Symptoms in Both Normal Weight and Overweight Women. N Engl J Med. 2006;35(22):2340-2348.

  8. Subak LL, et al. Obesity and Urinary Incontinence: Epidemiology and Clinical Research Update” J Urol. 2009 Dec;182(6 Suppl):S2-S7. 

  9. Romero-Corral A, et al. Interactions between obesity and obstructive sleep apnea: implications for treatment. Chest. 2010 Mar;137(3):711-719.

  10. Herrington WG, et al. Body-mass index and risk of advanced chronic kidney disease: Prospective analyses from a primary care cohort of 1.4 million adults in England. PLoS One. 2017;12(3):e0173515. 

  11. Yang G, et al. The effects of obesity on venous thromboembolism: A review. Open J Prev Med. 2012 Nov;2(4):499-509. 

  12. Bai L, et al. Incident gout and weight change patterns: a retrospective cohort study of US adults. Arthritis Res Ther. 2021;23:69.

  13. Cedars-Sinai. Metabolic Syndrome. 2022. https://www.cedars-sinai.org/health-library/diseases-and-conditions/m/metabolic-syndrome.html

  14. Kolb H, Martin S. Environmental/lifestyle factors in the pathogenesis and prevention of type 2 diabetes. BMC Med. 2017;15(1):131.

  15. Wildman RP, et al. The Obese Without Cardiometabolic Risk Factor Clustering and the Normal Weight With Cardiometabolic Risk Factor Clustering: Prevalence and Correlates of 2 Phenotypes Among the US Population (NHANES 1999-2004). Arch Intern Med. 2008;168(15):1617-1624.

  16. Wharton S, et al. Obesity in adults: a clinical practice guideline. CMAJ. 2020;192(31):875-891. 

  17. Brown J, Clarke C, Johnson Stoklossa C, Sievenpiper J. Canadian Adult Obesity Clinical Practice Guidelines: Medical Nutrition Therapy in Obesity Management. Accessed July 6, 2023. https://obesitycanada.ca/guidelines/nutrition.

  18. Hall KD, et al.  Ultra-processed diets cause excess calorie intake and weight gain: An inpatient randomized controlled trial of ad libitum food intake. Cell Metab. 2019;30(1):67e3-77e3

  19. Yau HC, Potenza MN. Stress and eating behaviours. Minerva Endocrinol. 2013;38(3):255-267.

  20. Obesity Prevention Source. 3 ways decreased sleep contributes to overeating. Harvard School of Public Health. 2023. http://hsph.harvard.edu/obesity-prevention-source/2010/01/01/3-ways-decreased-sleep-contributes-to-overeating-2/ 

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