Mothers who eat junk food during pregnancy and while breastfeeding have obesity-prone children, rat studies suggest.

Once weaned, the offspring of junk-food-fed mothers prefer junk foods more than the offspring of rats fed a healthy diet during pregnancy.

But even when fed a healthy diet, the offspring of the junk-food-fed mothers are fatter than the offspring of rats fed healthy food. Moreover, obesity-linked genes are more active in the offspring of junk-food-fed mothers -- especially female offspring.

"The maternal diet seems to influence and trigger events early in the life of their offspring," study researcher Stephanie Bayol, PhD, tells WebMD. "We found that by the end of their adolescence, the offspring from the junk-food-fed animals had increased blood sugar, blood fat, and decreased insulin sensitivity -- all of which are associated with overweight and diabetes."

Bayol and colleagues at London's Royal Veterinary College gave pregnant rats normal rat chow. But they also gave them free access to cookies, chocolate, doughnuts, muffins, potato chips, candy, and cheese.

In earlier studies, they showed that the offspring of these rats liked high-fat, high-salt, high-sugar foods better than other rats. But the new studies show that even when never fed junk food themselves, the rats whose mothers ate junk food during pregnancy grew up fatter than normal rats.

"Their fat cells were larger, which might make them more prone to obesity and might make it harder for them to lose weight," Bayol says. "So there were lasting effects from their mother's consumption of junk food, even if they were not fed junk food after weaning."

Interestingly, the effects seem to be stronger for female offspring than for males.

"Males seem to use a different molecular machinery to regulate fat storage than do females," Bayol says.

Does the same thing happen in humans? Of course, it would be unethical to feed junk food to pregnant women. But there's evidence that women's diets during pregnancy and breastfeeding affect their children's food preferences, says pediatrician Stephen R. Cook, MD, MPH, of Golisano Children's Hospital at the University of Rochester, N.Y.

"This gets to the concept of fetal programming. A lot of information suggests that in-utero exposures can lead to long-lasting effects in children," Cook tells WebMD. "Women who smoke during pregnancy have children who are heavier, so maternal patterns can affect a child's weight. Whether the cause is altered metabolism or something else, it is a very real concern."

On the other hand, Cook says, junk food is made to have tastes and textures that appeal to children. And it's heavily advertised, which also affects a child's preferences.

对老鼠的研究使人联想到：母亲在怀孕期间以及在哺乳时食用垃圾食品，可能造成有肥胖倾向的孩子。
一旦断奶，用垃圾食品喂养的母亲的后代，比在怀孕期间喂以健康饮食的老鼠的后代，更喜欢垃圾食品。

但是即使在喂以健康饮食时，用垃圾食品喂养的母亲的后代也比喂以健康饮食的老鼠的后代更肥胖一些。此外，在用垃圾食品喂养的母亲的后代中，与肥胖相联系的基因更为活动——尤其是雌性的后代。

“母方的饮食似乎在她们后代生命的早期就影响和触发事件的发生，”研究员斯蒂芬 贝约尔博士告诉 WebMD（网络医学博士）说。“我们在牠们的青春期结束之前发现，用垃圾食品喂养的母亲的后代具有增高的血糖、血脂以及降低的胰岛素敏感性——所有这一切都与超重和糖尿病相关。”

贝约尔和他在伦敦皇家兽医学院的同事们给孕鼠喂食正常的鼠食。但是他们也给了牠们自由接近饼干、巧克力、炸面圈、松饼、薯片、糖果和奶酪的机会。

在早期的研究中，他们展现出，这些喜欢高脂肪、高盐、高糖食物的老鼠的后代优于其他的老鼠。但是新的研究显示，即使在从未喂食过垃圾食品时，那些牠们的母亲在怀孕期间食用过垃圾食品的老鼠，也比正常的老鼠长得肥胖一些。

“牠们的脂肪细胞较大，这可能使牠们更容易肥胖，并且可能使得更难以为牠们减肥，”贝约尔说。“因此，即使牠们在断奶后没有喂过垃圾食品，还是有持久的影响来自牠们母亲对垃圾食品的消费。”

有趣的是，这种效果对于雌性后代似乎比雄性后代更强一些。

“雄性似乎使用与雌性不同的分子机制来调节脂肪的储存，”贝约尔说。

同样的事情在人类中发生吗？当然，给孕妇进食垃圾食品会是不道德的。但是，纽约州罗彻斯特大学哥里萨诺儿童医院的儿科医生、医学博士、公共卫生硕士斯蒂芬 R. 库克说，有证据表明，妇女在怀孕和哺乳期间的饮食，影响其子女的食物偏好。

“这一下子就谈起了胎儿设计的概念。很多资料表明，在子宫内的暴露接触可能导致对儿童长期持久的影响，”库克告诉 WebMD。“在怀孕期间吸烟的妇女就有较重一些的子女，所以，产妇的模式可能影响儿童的体重。是否因为代谢改变或者某种其它的原因，这是一件很值得实际关注的事情。”

在另一方面，库克说，垃圾食品做得具有吸引儿童的味道和质地。而且它大量地做广告，这也影响到孩子的喜好