White bread could be a large contributor to obesity.

This type of bread is a huge part of many people's diet, but it might not be a friend to the waistline, HealthDay reported.

Researchers looked at the eating habits and weights of over 9,200 participants for an average of five years.

The research team found that participants who only ate both white and whole grain breads did not have an elevated risk of weight gain. Patients who exclusively ate white bread and had more than two portions a day were 40 percent more likely to be overweight or obese than those who ate less than one portion a week, HealthDay reported.

Whole grain was not linked to obesity. The types of carbohydrates found in whole grain bread as well as the fiber content could be the reason behind this.

"Consumption of white bread [of] two portions per day or more showed a significant direct association with the risk of becoming overweight or obese," the researchers wrote, HealthDay reported.

The research does not show a cause-and-effect relationship between the consumption of white bread and weight gain; the study only provides an association between the two.

 "Refined grains such as white bread start to taste sweet in the mouth almost as soon as you eat it, that is the starch being broken down into sugar," Lead author Professor Miguel Martinez-Gonzalez from University of Navarra said, the Telegraph reported.  "It is this feeling that leaves you wanting more. When white bread is a staple food, eating at one or two main meals a day then this is a lot of extra calories on a daily basis."

"The message is clear, go for wholegrains instead of white bread when eating your meals," he said.