Body mass index (BMI) is a person’s weight in kilograms divided by the square of height in meters. BMI is an inexpensive and easy screening method for weight category—underweight, healthy weight, overweight, and obesity.

BMI interpretation

For adults 20 years old and older, BMI is interpreted using standard weight status categories. These categories are the same for men and women of all body types and ages.

Example,

 here are the weight ranges, the corresponding BMI ranges, and the weight status categories for a person whose height is 5′ 9″. (69 inches)

Health consequences of obesity for adults

People who have obesity are at increased risk for many diseases and health conditions which includes the following:

• High blood pressure (hypertension)
• High LDL cholesterol, low HDL cholesterol, or high levels of triglycerides (dyslipidemia)
• Type 2 diabetes
• Coronary heart disease
• Stroke
• Gallbladder disease
• Osteoarthritis (a breakdown of cartilage and bone within a joint)
• Sleep apnea and breathing problems
• Chronic inflammation and increased oxidative stress
• Some cancers (endometrial, breast, colon, kidney, gallbladder, and liver)
• Low quality of life
• Mental illness such as clinical depression, anxiety, and other mental disorders
• Body pain and difficulty with physical functioning

Reference:

National Institute of Health