Classification of Overweight and Obesity by Body Mass Index (BMI)
Index (BMI)
Category[12] BMI
Underweight < 18.5
Normal Weight 18.5 – 24.9
Overweight 25.0 – 29.9
Obesity (Class I) 30.0 – 34.9
Obesity (Class II) 35.0 – 39.9
Obesity (Class III) ≥ 40.0
This is the World Health Organization’s (WHO) recommended body weight based on BMI values for adults. It is used for both men and women, aged 18 or older.
Category BMI range – kg/m2
Severe Thinness < 16
Moderate Thinness 16 – 17
Mild Thinness 17 – 18.5
Normal 18.5 – 25
Overweight 25 – 30
Obese Class I 30 – 35
Obese Class II 35 – 40
Obese Class III > 40
Risks associated with being overweight
Being overweight increases the risk of a number of serious diseases and health conditions. Below is a list of said risks, according to the Centers for Disease Control and Prevention (CDC):
- High blood pressure
- Higher levels of LDL cholesterol, which is widely considered « bad cholesterol,« lower levels of HDL cholesterol, considered to be good cholesterol in moderation, and high levels of triglycerides
- Type II diabetes
- Coronary heart disease
- Stroke
- Gallbladder disease
- Osteoarthritis, is a type of joint disease caused by the breakdown of joint cartilage
- Sleep apnea and breathing problems
- Certain cancers (endometrial, breast, colon, kidney, gallbladder, liver)
- Low quality of life
- Mental illnesses such as clinical depression, anxiety, and others
- Body pains and difficulty with certain physical functions
- Generally, an increased risk of mortality compared to those with a healthy BMI
As can be seen from the list above, there are numerous negative, in some cases fatal, outcomes that may result from being overweight. Generally, a person should try to maintain a BMI below 25 kg/m2, but ideally should consult their doctor to determine whether or not they need to make any changes to their lifestyle in order to be healthier.
Risks associated with being underweight
Being underweight has its own associated risks, listed below:
- Malnutrition, vitamin deficiencies, anemia (lowered ability to carry blood vessels)
- Osteoporosis, a disease that causes bone weakness, increasing the risk of breaking a bone
A decrease in immune function - Growth and development issues, particularly in children and teenagers
- Possible reproductive issues for women due to hormonal imbalances that can disrupt the menstrual cycle. Underweight women also have a higher chance of miscarriage in the first trimester
- Potential complications as a result of surgery
- Generally, an increased risk of mortality compared to those with a healthy BMI
- In some cases, being underweight can be a sign of some underlying condition or disease such as anorexia nervosa, which has its own risks. Consult your doctor if you think you or someone you know is underweight, particularly if the reason for being underweight does not seem obvious