A new medical study has debunked the idea that obese people have smaller chances of developing various types of illnesses than their lighter counterparts, according to NY Daily News.

The notion of healthy obesity stems from previous reports claiming that certain overweight individuals do not suffer from usual health problems that are associated with being obese.

According to these reports, some people do not have high sugar levels, high blood pressure or cholesterol and heart problems despite being overweight.

However, based on a study conducted by University College London doctoral student Joshua Bell, the concept of healthy obesity only happens momentarily. Bell explained that eventually, those who maintain a high body mass index for a long period of time will develop obesity-related health problems.

Bell and his team of researchers came up with their findings after analyzing the health data spanning 20 years of over 2,500 individuals.

The first years of the report showed that more than half of the subjects had conditions that can be categorized as healthy obese. However, after the study reached its halfway point, 40 percent of those who were once called healthy obese began to develop illnesses.

After twenty years, more than half of the individuals were ranked as unhealthy.

"Healthy obesity is something that's a phase rather than something that's enduring over time," Bell said in a statement to Health Day. "It's important to have a long-term view of healthy obesity, and to bear in mind the long-term tendencies."

"As long as obesity persists, health tends to decline," he added. "It does seem to be a high-risk state."

Dr. David Freeman, head of the heart failure services at New York's Franklin Hospital noted that the new study indicates that despite not experiencing symptoms of diseases, people who are overweight should follow necessary steps to ensure a healthier lifestyle.

"The longer one is obese, the more likely they are to induce damage," he told Health Day. "I have very seldom seen people who are obese for the long-term not have a condition that requires treatment."

"All types of obesity warrant treatment, even those which appear to be healthy, because they carry a high risk of future decline," Freeman added.