What's behind weight gain?
Obesity isn't a matter of willpower. It's a complex condition influenced by genetics, hormones and other biological factors.
Your result: Normal weight
Your weight is within the normal BMI range.
Recommendation
The medical community recommends that you keep your weight within this range.
| Classification | BMI |
| Underweight | Below 18.5 |
| Normal weight | 18.5–24.9 |
| Overweight | 25–29.9 |
| Obesity | 30 and above |
| Class I | 30–34.9 |
| Class II | 35–39.9 |
| Class III | 40 and above |
This BMI calculator is for adults 20 years or older. Talk to your doctor about your BMI if you're under the age of 20.1
It's important to know that this classification can vary in certain ethnic groups, such as Indigenous Peoples, South Asians, Chinese and other populations. Always check with your healthcare professional about the suitability of this BMI classification based on your own circumstances.1
Frequently asked Questions
Why is BMI important to know?
BMI is a good way to check your risk of diseases related to body fat. Living with overweight or obesity is associated with an increased risk of mortality and other diseases or conditions. Generally, the higher your BMI, the greater the chance of developing other chronic obesity-related diseases, including:
- Type II diabetes
- Cardiovascular disease
- Stroke
- High blood pressure
- Infertility
- Depression and anxiety
- Coronary heart disease
- Dyslipidemia
- Metabolic Dysfunction-Associated Steatohepatitis (MASH)
- Gastroesophageal reflux disease (GERD)
- Metabolic syndrome (MetS)
- Urinary incontinence
- Obstructive sleep apnea and breathing problems
- Chronic kidney disease
- Various types of cancer: including but not limited to - breast, colon, endometrial, oesophageal, kidney, ovarian, and pancreatic cancer
- Knee osteoarthritis
- Gallstone disease
- Thrombosis
- Gout
- Increased risk of mortality compared to those with a healthy BMI
Ask a doctor 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:
- Hereditary 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 diet and lifestyle. Talk to a doctor about your weight and health and evaluate what actions may be needed.
Tools to help you
Essential tools to monitor your health and have productive conversations with a doctor.
Take the first step and find the doctor for you
Talk to a doctor about treatment options that could help prevent the weight you lose from coming back.
References
- Rueda-Clausen CF, et al. Canadian Adult Obesity Clinical Practice Guidelines: Assessment of People Living with Obesity. Available at: obesitycanada.ca/guidelines/assessment. Accessed April 2025.
- Brown J, et al. Canadian Adult Obesity Clinical Practice Guidelines: Medical Nutrition Therapy in Obesity Management. Available from: obesitycanada.ca/guidelines/nutrition. Accessed April 2025.
- Chao A, et al. J Health Psychol 2015;20:721–9.
- Yumuk V, et al. Obes Facts 2015;8:402–24.
- Taheri S, et al. PLoS Med 2004;1:e62.
- Prospective Studies Collaboration. Lancet 2009;373(9669):1083–96.
- Guh DP, et al. BMC Public Health 2009;9:88.
- Klop B, et al. Nutrients 2013;5(4):1218–40.
- Adair T & Lopez AD. BMC Med 2020;18(1):199.
- Gelber RP, et al. Am J Hypertens 2007;20(4):370–7.
- Lee HJ, et al. PLoS One 2018;13(3):e0195210.
- Panidis D, et al. Fertil Steril 2008;89(4):899–906.
- Dong C, et al. Int J Obes Relat Metab Disord 2004;28(6):790–5.
- Loomis AK, et al. J Clin Endocrinol Metab 2016;101:945–52.
- Zafar S, et al. Saudi J Gastroenterol 2008;14:53–57.
- Han TS, et al. JRSM Cardiovasc Dis 2016;5:2048004016633371.
- Subak LL, et al. J Urol 2009;182(6 Suppl):S2–S7.
- Modena DAO, et al. Rev Assoc Med Bras (1992) 2017;63(10):862–8.
- Herrington WG, et al. PLoS One 2017;12:e0173515.
- Bhaskaran K, et al. Lancet 2014;384:755-65.
- Zheng H, et al. BMJ Open 2015;5:e007568.
- Su YP, et al. BMC Gastroenterol 2019;19:117.
- Bai L, et al. Arthritis Res Ther 2021;23:69.
- Heymsfield SB, et al. Obes Rev 2016;17:262–75.
- Romero-Corral A, et al. Int J Obes (Lond) 2008;32:959–66.
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AU23OB00080 - July 2025