It’s Not Just Mom’s Diet: Father’s Junk Food Habit May Shape His Unborn Baby
Health09 August 2026ByPeter Dockrill
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The more we find out about ultra-processed foods, the more we lose our appetite
These industrially formulated food products are low in nutrients and high in all kinds of dubious additives, and they’re increasingly taking over the modern diet
That’s a problem, because scientists keep uncovering new evidence of the health issues posed by ultra-processed foods, which have been linked to cancer, neurodegenerative diseases, and much more
But the risks of ultra-processed food aren’t just to the person eating it. Even the next generation could be affected, research suggests
A new study in Nutrition Research by scientists in Brazil suggests fathers’ consumption of ultra-processed foods may affect fat distribution in their future children, with those effects seeded before their babies are even conceived
“Maternal nutrition and health before, during, and after the baby’s birth have always received attention, but little is said about the role of the father’s diet,” says nutritional epidemiologist Daniela Sartorelli from the University of São Paulo
“Our study shows that it also matters a great deal for the baby’s health.”
In their study, Sartorelli’s team analyzed a group of 43 family units, consisting of a mother, a father, and a newborn. The researchers first recruited pregnant women, before later inviting their partners to join the study
During the study, the parents were interviewed on two occasions about the food and drink they had consumed during the last 24 hours, with the researchers subsequently calculating how much of each individual’s energy intake was
Later, once each couple’s baby was born, the researchers collected comprehensive measurements of the infant’s body, including birth weight and length, body circumference, skin-fold measurements, and assessments of body composition
Subsequent analysis of the data showed higher intake of ultra-processed food by fathers was associated with babies having higher birth weight, more weight relative to their height, and thicker skin-folds on their thighs and around their hips
“Although the study didn’t find an increase in total body fat, only fat accumulation in certain regions of the baby’s body, the results suggest that the quality of the father’s diet may also influence fetal development,” Sartorelli explains
“This is important because, on average, ultra-processed foods accounted for 30 percent of the total energy consumed by the fathers whose diets were analyzed in the study, particularly processed meats, sugary drinks, and cookies.”
It’s worth noting that this study only shows a correlation in the data, and doesn’t prove that fathers eating ultra-processed foods affect their offspring’s body composition
But the finding adds to growing evidence that fathers’ health and lifestyles may influence their children’s development before birth, potentially through epigenetic changes carried in sperm
“Paternal poor nutrition has been associated with alterations in sperm quality and epigenetic markers, leading to a high likelihood of metabolic disorders,” the researchers write in their paper
“Ultra-processed foods are known for their inflammatory potential as they increase the production of reactive oxygen species (ROS) that mediate inflammation, which can directly affect sperm quality and motility
” Epigenetic changes, particularly DNA methylation, carried by sperm are a possible mechanism explaining how paternal exposure to the environment can affect the offspring development.”
One such pathway is that a father’s intake of ultra-processed foods might disrupt the gene IGF-II, which babies inherit from their father and which encodes the protein IGF-II, involved in fetal growth
“Previous studies have shown that a father’s dietary habits can biochemically modify this gene in sperm,” says first author and nutrition researcher Mariana Carvalho from the University of São Paulo
“Diets rich in ultra-processed foods can create a pro-inflammatory environment in the body, affecting sperm quality and altering the expression of genes that will be passed on to the baby.”
While it will take additional studies to confirm the epigenetics hypothesis is responsible for changes in infant birth weight and body composition, the researchers say anybody thinking of starting a family should think about how their diet today might affect a future child
“The quality of the father’s diet before conception has a significant impact on the baby’s health,” Sartorelli says
“The results pave the way for larger studies and reinforce the need to include men, not just women, in family planning guidance.”
The findings are reported in Nutrition Research
This article was fact-checked by Clare Watson and edited by Clare Watson. While we pride ourselves on our process, we are only human. If you spot a mistake, please let us know
