Mothers who ate high-calorie food during the pregnancy and lactation period have babies who are already addicted to junk food, according to a new study.

The study was conducted by researchers from University of Adelaide, who found that these highly palatable foods reduced the sensitivity of the normal reward system when the mothers ate food containing high amounts of fat and sugar.

A previous study on rats had shown that mothers on a high-fat diet have an increased risk of having babies with nonalcoholic fatty liver disease. According to Medline Plus, pregnant women should manage their weight by eating nutritious food and avoiding high-calorie foods like cookies, chips, cakes, etc.

The present study links maternal diet to the production of opioids in the baby. Opioids are produced in the body in response to fat and sugar, and these opioids are the ones that stimulate the "pleasure" hormone called dopamine.

"We found that the opioid signalling pathway (the reward pathway) in these offspring was less sensitive than those whose mothers were eating a standard diet," said Dr. Bev Mühlhäusler, Postdoctoral Fellow in the University's FOODplus Research Centre and lead author of the study. Less sensitivity of the reward pathway leads to a desire to get more of the factor (in this case food) that helps produce the feel-good response in the brain. The present study shows that some babies have this desire to eat junk food before they were even born.

The concept of food addiction has been studied widely, especially from a neurochemical perspective. However, there are still some doubts over whether or not addiction to food is a valid concept.

Researchers from the present study add that mothers need to be careful about their diets, both during pregnancy and the lactation period.

"The take-home message for women is that eating large amounts of junk food during pregnancy and while breastfeeding will have long-term consequences for their child's preference for these foods, which will ultimately have negative effects on their health," Dr. Mühlhäusler added, according to a news release. 

The study is published in the FASEB Journal.