She and a very small group of very thin people like her have given scientists surprising clues to one of the most important questions about obesity: Why do fat people often develop serious and sometimes life-threatening medical conditions?
The answer, it turns out, has little to do with the fat itself. It’s about each person’s ability to store it. With that understanding, scientists are now working on drug treatments to protect people from excess unstored fat and spare them from dire medical conditions.
The need is clear. One in three Americans and one in four adults worldwide have at least three conditions associated with obesity such as diabetes, highcholesterol and high blood pressure — a combination of disorders that doubles their risk of heart attacks and strokes. In addition, 2 percent to 3 percent of adults in America, or at least five million people, have a grave accumulation of fat in their livers caused by obesity that can lead to liver failure.
The detective work that led to this new scientific understanding of fat began with a small group of scientists curious about a disorder that can be caused by a gene mutation so rare it is estimated to affect just one in 10 million people, including, it turned out, Ms. Johnson.
For much of her life, Ms. Johnson, 55, had no idea anything was amiss. Yes, she was very thin and always ravenous, but in Jamaica, where she was born, many children were skinny, she says, and no one thought much of it. She seemed healthy, and she developed normally through adolescence.