Eating hamburgers, pizza may increase cancer risk: Study

The researchers wanted to find out how the ratio of energy to food weight, otherwise known as dietary energy density (DED), contributes to cancer risk. They looked at DED in the diets of post-menopausal women.

The findings, published in the Journal of the Academy of Nutrition and Dietetics, showed that consuming energy dense foods was tied to a 10 per cent increase in obesity-related cancer among normal weight women. 

"The demonstrated effect in normal-weight women in relation to risk for obesity-related cancers is novel," explained lead investigator Cynthia Thomson, Professor at Mel and Enid Zuckerman College of Public Health, University of Arizona in the US

"This finding suggests that weight management alone may not protect against obesity-related cancers should women favour a diet pattern indicative of high energy density," Thomson said. 

Dietary energy density is a measure of food quality and the relationship of calories to nutrients. The more calories per gram of weight a food has, the higher its DED. 

Whole foods, including vegetables, fruits, lean protein, and beans are considered low in energy density because they provide a lot of nutrients using very few calories. 

Processed foods, like hamburgers and pizza, are considered high in energy density because you need a larger amount to get necessary nutrients

In order to gain a better understanding of how DED alone relates to cancer risk, researchers used data on 90,000 postmenopausal women including their diet and any diagnosis of cancer. 

The researchers believe that the higher dietary energy density foods in normal-weight women may cause metabolic dysregulation that is independent of body weight, which is a variable known to increase cancer risk.

While further study is needed to understand how dietary energy density may play a role in cancer risk for other populations such as young people and men, this information may help persuade postmenopausal women to choose low energy dense foods, even if they are already at a healthy body mass index.

"Among normal-weight women, higher DED may be a contributing factor for obesity-related cancers," Thomson said. 

"Importantly, DED is a modifiable risk factor. Nutrition interventions targeting energy density as well as other diet-related cancer preventive approaches are warranted to reduce cancer burden among postmenopausal women," Thomson added.