Most people know they need to lose weight for a variety of health reasons if they’re obese—that is, their body mass index (BMI, a ratio of weight to height) is 30 or more. But the health risks tied to weight aren’t a simple matter of crossing a line into obesity. A new study shows that the heavier you are, the greater your health risks, beginning in the overweight category, with a BMI of 25-29.9.
Doctors have actually defined three categories of obesity: obesity 1, with a BMI of 30-34.9; obesity 2 (35-39.9); and extreme obesity (40). A research team supported by NIH set out to look at the relationship of these different levels of obesity to mortality and heart disease.
The researchers studied data from over 90,000 women between 50 and 79 years old over a 7-year period. They found that the risk for mortality was almost 25% higher for women in the obesity 1 category than for those in the normal range, about 50% higher for obesity 2, and almost 75% higher for those with extreme obesity. The risk of heart disease was strongly related to weight as well, with a higher risk beginning for people in the overweight range. Severely obese women also had higher rates of diabetes and high blood pressure than women in the lower weight classes.
The rates of extreme obesity differed with race and ethnicity, ranging from 1% among Asian and Pacific Islanders to 10% among black women. However, once the women’s weights were taken into account, the mortality and heart disease rates didn’t differ by race or ethnicity.
This study shows that the more overweight you are, the greater your health risks. It’s important to maintain a healthy weight and to get appropriate treatment if you struggle with obesity.