First you have the body news and its development. You learn about BMI and its relation to the relevant whatever. Analyses are done to show why the symptom is implicated in the disease. You hear about solutions if you are one of those with a real problem. You start to notice who among your friends has the problem and how worried they seem. Whatever it is, your doctor assures you that you will have less of a problem if you lose weight.
And then five or ten years later, you learn the new body news: the old body news was completely wrong. For example, from the NY Times, March 22, 2011:
A major new analysis challenges the long-held idea that obese people who carry their extra weight mainly around the middle — those with an “apple” shape — are at greater risk for heart disease than “pears,” whose fat tends to cluster on their thighs and buttocks. …
Conventional risk factors like blood pressure, cholesterol, diabetes and smoking were accurate predictors of a heart attack or stroke, but additional information about weight or body shape (ascertained by measuring waist circumference or waist-to-hip ratio) did not improve the ability to predict risk.
“Whatever your shape is doesn’t really matter,” said Dr. Emanuele Di Angelantonio, a lecturer at the University of Cambridge and a member of the Emerging Risk Factors Collaboration, which carried out the study.