Women who eat junk food but are not overweight are still increasing their risk of cancer, a study reveals.
According to earlier research the risk of cancer increased because processed foods such as burgers and pizza made people overweight.
However, according to the latest study, such high energy-low nutrient foods increased risk of developing cancer in women by 10 per cent even if they were of normal weight.
The findings, published in the Journal of the Academy of Nutrition and Dietetics, used figures from 90,000 postmenopausal women in the US to assess their diet and any cancer diagnosis.
Thomson, of the University of Arizona, said, ''The demonstrated effect in normal-weight women in relation to risk for obesity-related cancers is novel and contrary to our hypothesis.
''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.''
The study focuses on high dietary energy density (DED) foods such as biscuits and confectionery, which is a measure of food quality and the relationship of calories to nutrients.
The more calories per gram of weight in a food, the higher its DED.
Whole foods including vegetables, fruits, lean protein, and beans - are considered low-DED foods as they provide a lot of nutrients using very few calories.
The research focused on women but it is believed that both sexes may be affected.
According to current research an estimated 30 per cent of cancers could be prevented through changes in diet.
But while there existed a proven link between obesity and certain cancers, less is known about how the ratio of energy to food weight – otherwise known as dietary energy density (DED) – contributes to cancer risk, according to experts.