The offspring of rats fed fatty, processed food had high levels of fat in their bloodstream and around major organs even after adolescence.
The animals had a raised diabetes risk – even if they ate healthily.
The study, by the Royal Veterinary College and London’s Wellcome Trust, features in The Journal of Physiology.
Another study by the same team also showed that rats whose mothers were fed junk food during pregnancy and breastfeeding were more likely to crave similar snacks themselves.
Dr Stephanie Bayol, one of the researchers, said:
“It seems that a mother’s diet whilst pregnant and breastfeeding is very important for the long-term health of her child.
“We always say: ‘You are what you eat’, but in fact it may also be true that you are what your mother ate.”
Of particular concern was fat gathering around the major organs, which has been implicated in the development of type II diabetes.
Like usual, there were interesting differences between the sexes. Male offspring of unhealthy mothers have higher levels of insulin and normal blood sugar, while the reverse was true of females, who also tended to be fatter.