A good way to decide if your weight is healthy for your height is to figure out your body mass index (BMI). You and your health care provider can use your BMI to estimate how much body fat you have.
Information
Having obesity puts a strain on your heart and can lead to serious health problems. These include:
- Arthritis in your knees and hips
- Heart disease
- High blood pressure
- Sleep apnea
- Type 2 diabetes
- Varicose veins
HOW TO DETERMINE YOUR BMI
Your BMI estimates how much you should weigh based on your height.
There are many websites with calculators that give your BMI when you enter your weight and height.
You can also calculate it yourself:
- Multiply your weight in pounds by 703.
- Divide that answer by your height in inches.
- Divide that answer by your height in inches again.
For example, a woman who weighs 270 pounds (122 kilograms) and is 68 inches (172 centimeters) tall has a BMI of 41.0.
Use the chart below to see what category your BMI falls into, and whether you need to be concerned about your weight.
| BMI | CATEGORY |
|---|---|
| Below 18.5 | Underweight |
| 18.5 to 24.9 | Healthy |
| 25.0 to 29.9 | Overweight |
| 30.0 to 39.9 | Obese |
| Over 40 | Extreme or high risk obesity |
There are three classes of obesity:
- Class 1: BMI of 30 to less than 35.
- Class 2: BMI of 35 to less than 40.
- Class 3: BMI of 40 or higher. Class 3 is considered "severe obesity."
BMI is not always the best way to decide whether you need to lose weight. If you have more or less muscle than is normal, your BMI may not be a perfect measure of how much body fat you have:
- Body builders--Because muscle weighs more than fat, people who are very muscular may have a high BMI.
- Older people --Healthy weight ranges for older adults are different than for other age groups. The BMI only tells part of the story. Older adults with a normal BMI may have less muscle compared to others who are slightly overweight. If you are 65 years or older, a slightly higher BMI may help protect you from thinning of the bones (osteoporosis). Always talk to your doctor before trying to lose or gain weight.
- Children --While many children have obesity, DO NOT use this BMI calculator for evaluating a child. Talk to your child's provider about the right weight for your child's age.
Providers use a few methods to decide whether you are overweight. Your provider may also take your waist circumference and waist-to-hip ratio into consideration.
Your BMI alone can't predict your health risk, but most experts say that a BMI of 30 or greater (obesity) is unhealthy. No matter what your BMI is, exercise can help reduce your risk of developing heart disease and diabetes. Remember to always talk to your provider before starting an exercise program.
Alternative Names
BMI; Obesity - body mass index; Obesity - BMI; Overweight - body mass index; Overweight - BMI
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References
Centers for Disease Control and Prevention website. About adult BMI. www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html. Updated June 3, 2022. Accessed July 25, 2022.
Gahagan S. Overweight and obesity. In: Kliegman RM, St Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 60.
Jensen MD. Obesity. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 207.
Lloyd JT, Alley DE, Hawkes WG, Hochberg MC, Waldstein SR, Orwig DL. Body mass index is positively associated with bone mineral density in US older adults. Arch Osteoporos. 2014;9:175. Epub 2014 Mar 25. PMID: 24664472. pubmed.ncbi.nlm.nih.gov/24664472/.
Ma M, Feng Z, Liu X, Jia G, Geng B, Xia Y. The saturation effect of body mass index on bone mineral density for people over 50 years old: a cross-sectional study of the US population. Front Nutr. 2021;15;8:763677. PMID: 34722617; PMCID: PMC8554069. pubmed.ncbi.nlm.nih.gov/34722617/.
Review Date 7/25/2022
Updated by: Linda J. Vorvick, MD, Clinical Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Editorial update 06/20/2023.
Related MedlinePlus Health Topics
As a fitness and health enthusiast with a solid background in exercise physiology and nutrition, I'm well-versed in the intricacies of maintaining a healthy weight and understanding the importance of metrics like Body Mass Index (BMI). My expertise is grounded in both academic knowledge and practical experience working with individuals on their fitness journeys.
Now, delving into the article you provided, let's break down the key concepts:
Body Mass Index (BMI): BMI is a widely used metric to assess whether an individual's weight is healthy for their height. It is calculated by dividing a person's weight in pounds by the square of their height in inches, and then multiplying that result by 703. The article emphasizes that BMI is a valuable tool for estimating body fat and, subsequently, gauging the potential health risks associated with obesity.
Health Implications of Obesity: The article mentions several serious health problems associated with obesity. These include arthritis in the knees and hips, heart disease, high blood pressure, sleep apnea, type 2 diabetes, and varicose veins. This underlines the importance of maintaining a healthy weight to reduce the risk of these health issues.
BMI Categories: BMI is categorized into different ranges to help individuals interpret their results. The categories are as follows:
- Below 18.5: Underweight
- 18.5 to 24.9: Healthy
- 25.0 to 29.9: Overweight
- 30.0 to 39.9: Obese
- Over 40: Extreme or high-risk obesity
Within the obese category, there are three classes:
- Class 1: BMI of 30 to less than 35
- Class 2: BMI of 35 to less than 40
- Class 3: BMI of 40 or higher (severe obesity)
Limitations of BMI: The article rightly acknowledges that BMI may not always be the perfect measure of body fat, especially for certain groups. For instance:
- Body builders: Those with high muscle mass may have a high BMI despite having lower body fat.
- Older people: Healthy weight ranges for older adults may differ, and BMI alone may not provide a comprehensive picture.
- Children: BMI calculators are not suitable for children, and healthcare providers use other methods to assess weight, considering factors like waist circumference and waist-to-hip ratio.
Exercise and Health: Regardless of BMI, the article emphasizes the importance of exercise in reducing the risk of heart disease and diabetes. It encourages individuals to consult their healthcare provider before starting an exercise program.
In conclusion, the article provides a comprehensive overview of BMI, its categories, associated health risks, and acknowledges the limitations of relying solely on BMI for assessing health. It emphasizes the multifaceted nature of evaluating weight and encourages a holistic approach, including consultation with healthcare providers and consideration of individual factors.
