For years, medical experts have been baffled by how a certain segment of the population qualifies as both obese and metabolically healthy. Now a new study has uncovered the magic in the metabolism of those individuals, reported the New York Times on October 9. And it all comes down to the mighty but misunderstood mitochondria.
Researchers discovered that when they analyzed the fat cells of people who are obese but otherwise have healthy test results (cholesterol, blood sugar, blood pressure and no diabetes) and compared them to those who are obese and suffer from the typical metabolic red flags, the unhealthy obese had impaired mitochondria. Healthy mitochondria give our bodies the ability to reap energy from food while controlling the amount of fat cells that we generate. And that's the distinction, discovered the researchers:
- "Metabolically healthy obese" people have a different type of fat tissue. It produces new cells to store fat.
- "Unhealthy obese" people have fat cells that behave differently. They grow larger, putting stress on the cells until they die. And when that process happens, inflammation occurs.
While "healthy obese" people do not suffer from that cycle leading to inflammation, it produces dire effects in most extremely overweight individuals, revealed the new research study. Fat accumulates in organs where it should not appear, such as the liver, skeletal muscle and heart. Fatty livers typically parallel the development of metabolic abnormalities: They may result in insulin resistance, causing type 2 diabetes.
And then we have the fortunate healthy obese. In those individuals, the fat stays below the skin in the subcutaneous padding. Located there, no harm appears to occur.
“The group that doesn’t gain fat in the liver as they get obese seems to avoid inflammation and maintain their metabolic health,” said Dr. Jussi Naukkarinen, a research scientist specializing in internal medicine at the University of Helsinki. “There is a complete difference in how they react to obesity.”
However, there's a catch-22. Only 12 percent of those studied fell into the "metabolically healthy obese" category. And of those, some developed problems.
“We found that about a third of these people progressed down the road to being metabolically unhealthy,” said Sarah Appleton, a research fellow at the University of Adelaide. “Metabolically healthy obesity may essentially be a transient state.”
However, some did not travel down the path to ill health, said Dr. Naukkarinen. In his new study, some had no problems despite being categorized as obese.
“The metabolically healthy obese individuals are in the minority,” he said. “Most people tend to go along the not so healthy lines. But you do see some who have been obese for a long time and maintain their healthy profile.”
The team hopes that their discovery will lead to methods of helping metabolically unhealthy obese individuals get a second chance at health.