In 1993 and 1999, the nurses completed surveys about their lifestyle and health. To determine how healthy these women believed they were, the researchers asked "How would you rate your health in general?"
While the researchers suspected that BMI and self-reported health would be related, they were surprised at the results. Women who were of normal weight, but reported poor health, were more likely to gain weight over the course of the study. Overweight women who lost weight did not report better health at a lower weight. Perceptions about our bodies are hard to shake.
The researchers proposed that women with unhealthy lifestyles were likely to report poor health. Underlying illness is also a factor. But I suggest that the women's feelings about their body also played a part.
This study is of special interest to young people, because we're currently developing lifelong habits. If you're thin now, but engaging in other unhealthy behaviors, they will catch up with you later in life. And if you don't feel good about your body, and you don't recognize it's capacity, you likely won't take care of it.