Hundreds of previous studies have showed that obesity comes with a number or risks, such as heart disease or metabolic problems. However, the latest studies on obesity comes to contradict this theory, showing that one in three obese Americans appears to have no increased signs of heart risks.

For the study, Albert Einstein College researchers Rachel P. Wildman, PhD, Judith Wylie-Rosett, EdD, and colleagues analyzed medical records from 5,440 people who took part in the National Health and Nutrition Examination Surveys from 1999 through 2004.

Surprisingly, they found that 31.7 percent of obese volunteers (approximately 19.5 million adults) and 51.3 percent of overweight volunteers were “metabolically healthy,” (approximately 35.9 million adults). More exactly, they showed no signs of complications in tests for blood pressure, cholesterol, triglycerides, blood sugar, and inflammation and insulin resistance.

What was even more surprising was the fact that at the same time 23.5 percent of those having a healthy weight didn’t have the same beneficial scores on tests for metabolism and cardiovascular disease. This percentage translates into approximately 16.3 million Americans.

“We really don’t know as much about obesity as we think we do. A considerable proportion of overweight and obese US adults are metabolically healthy, whereas a considerable proportion of normal-weight adults express a clustering of cardiometabolic abnormalities. Our study shows you can still be healthy even if you are obese,” Dr. Wylie-Rosett said.

The exact explanation of these findings was given by a second study by researchers at University of Tubingen Germany. The study analyzed 314 German adults with traditional risk factors for type 2 diabetes and heart disease such as obesity, a family history of type 2 diabetes or a personal history of high blood sugar or gestational diabetes.

The researchers used magnetic resonance imaging to look at precisely how much body fat the participants had and where it was positioned. They concluded that the obese participants could have healthy heart and arteries and that fat on the liver might be the answer to what is causing heart disease or metabolic problems.

"Our data suggest that ectopic fat accumulation in the liver may be more important than visceral fat in the determination of such a beneficial phenotype in obesity," the researchers wrote.

No matter how good these findings look for overweight and obese people, they still have to do something about their diet, Elisa Zied, a spokeswoman for the American Dietetic Association cautioned. “I don’t want it to be an excuse for overweight people to eat an unhealthy diet,” she said.

The effects of obesity on the body will still be seen in time. Therefore, people should have a healthy diet and be physically active in order to prevent diseases. Maybe obesity doesn’t lead to heart disease or metabolic problems, but it shouldn’t be forgotten that a number of studies linked the condition with an increased risk of cancer.

The studies were published in the August 14 issue of the Archives of Internal Medicine.