Jan 02, 2015 06:30 PM EST By J Baulkman, UniversityHerald Reporter

Obesity does not always go hand in hand with metabolic changes in the body that can lead to diabetes, heart disease and stroke, according to a recent study.

Researchers from Washington University School of Medicine in St. Louis found that a subset of obese people do not have common metabolic abnormalities associated with obesity, such as insulin resistance, abnormal blood lipids (high triglycerides and low HDL cholesterol), high blood pressure and excess liver fat.

In addition, obese people who didn't have these metabolic problems when the study began did not develop them even after they gained more weight.

The study involved 20 obese participants who were asked to gain about 15 pounds over several months to determine how the extra pounds affected their metabolic functions.

"Our goal was to have research participants consume 1,000 extra calories every day until each gained 6 percent of his or her body weight," Elisa Fabbrini, first author of the study, said in a statement. "This was not easy to do. It is just as difficult to get people to gain weight as it is to get them to lose weight."

All of the subjects gained weight by eating at fast-food restaurants, under the supervision of a dietitian.

Before and after weight gain, the researchers carefully evaluated each study subject's body composition, insulin sensitivity and ability to regulate blood sugar, liver fat and other measures of metabolic health.

After gaining weight, the metabolic profiles of obese subjects remained normal if they were in the normal range when the study began. But the metabolic profiles significantly worsened after weight gain in obese subjects whose metabolic profiles already were abnormal when the study got underway.

"This research demonstrates that some obese people are protected from the adverse metabolic effects of moderate weight gain, whereas others are predisposed to develop these problems," said Samuel Klein, senior investigator of the study,

"This observation is important clinically because about 25 percent of obese people do not have metabolic complications," he added. "Our data shows that these people remain metabolically normal even after they gain additional weight."

As part of the study, the researchers then helped the subjects lose the weight they had gained.

The findings are detailed in The Journal of Clinical Investigation.

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