BMI stands for Body Mass Index. It is a calculation based on a person’s height and weight to determine if they are at the ideal body weight, underweight, or overweight. This formula is not always 100% accurate — it is possible for some people with a more muscular build to have a BMI that puts them in the overweight category even though they are not (since muscle weighs more than fat). According to the National Heart, Lung and Blood Institute, a BMI under 18.5 is underweight. Normal weight is the range from 18.5-24.9, overweight is 25-29.9 and a BMI of 30 or more is considered obese. Individuals who are overweight are at higher risk for a range of health conditions including osteoarthritis.
When you’re carrying extra weight on your body that adds pressure to your knee joints, especially the cartilage that helps them move smoothly. The more pressure you place on them the faster the cartilage in your knees wears away, thus the less smoothly your knees are able to move. Being overweight by only ten pounds increases the force on the knee by 30-60lbs. Reducing your BMI by lowering your body weight can relieve pressure on your knees and therefore decrease your risk of health issues related to having a high BMI.