Scientists have issued a stark warning that pregnant women who consume diets high in fatty foods could be inadvertently increasing their child's risk of developing obesity later in life. The caution follows new research which suggests that even the smell of such foods, like bacon, during pregnancy and breastfeeding may trigger lasting changes in a baby's brain linked to weight gain.
The 'Bacon Smell' Experiment
Researchers from the Max Planck Institute for Metabolism Research in Cologne, Germany, conducted a study on mice to investigate this link. They fed two groups of pregnant mice an identical, nutritionally balanced diet. However, they added an artificial bacon flavour to the food of one group. The scientists believed the odour molecules would reach the pups both in the womb and later through their mother's milk.
Over a follow-up period of nearly six months, tracking the mice from birth to adulthood, the team conducted a series of tests. These included insulin tolerance checks, blood glucose measurements, and analyses of body composition.
Key Findings and Brain Changes
The study, published in the journal Nature Metabolism, revealed that while maternal weight and fetal weight gain were similar for both groups, the offspring exposed to the bacon-flavoured diet showed significant differences. When fed a high-fat diet in adulthood, these mice exhibited increased body fat accumulation, insulin resistance, and reduced energy expenditure.
Crucially, brain activity analyses showed altered function in key brain regions and hunger neurons in these animals. The researchers stated this pattern resembled responses typically seen in obese animals. They theorise that early exposure to artificial flavours may create a 'mismatched association' between a food's sensory signals and its expected calorie content, potentially programming long-term physiological and behavioural responses.
Implications for Public Health in the UK
The researchers emphasised the importance of their insights, given the large number of women who consume high-fat diets during pregnancy and lactation. They noted that even healthy-weight mothers exposed to such diets might unknowingly elevate their offspring's future obesity risk.
This research adds to the growing concern over obesity rates in the UK. Current figures show more than a quarter of adults and a fifth of Year Six pupils in England are now classed as obese. The government has recently implemented anti-obesity measures, including restrictions on 'buy one, get one free' deals for unhealthy snacks and a forthcoming ban on online adverts for such products before 9 pm.
The study also highlights the broader health crisis, as excess weight is linked to at least 13 types of cancer and has fuelled a 39% rise in type 2 diabetes among under-40s in the UK. With the sense of smell developing in fetuses as early as the 24th week of pregnancy, the findings suggest maternal diet choices have profound and lasting consequences.
