The phrase “dad bod” is often used playfully to describe the softer physique some men develop after becoming fathers. But new UC Irvine research suggests that the concept may have more serious implications than previously understood.

A review published in Current Obesity Reports finds that a father’s health before and during parenthood – including obesity, diet, stress levels, mental health and lifestyle habits – may influence a child’s risk of obesity and related chronic diseases, even before conception occurs. 

The findings challenge the long-standing focus on maternal health as the primary driver of childhood obesity risk and point to fathers as important contributors to children’s lifelong well-being.

Matthew Landry, assistant professor of population health & disease prevention in the UC Irvine Joe C. Wen School of Population & Public Health and corresponding author of the study, says fathers have a larger role in children’s health than many people realize.

“We found that fathers’ health as an important contributor to children’s health through biological, behavioral and environmental pathways,” said corresponding author Matthew Landry, assistant professor of population health & disease prevention and a registered dietitian nutritionist. 

The review examined evidence showing that obesity may affect sperm quality and alter epigenetic markers – biological signals that help regulate how genes function during early development. Researchers believe these changes may influence a child’s metabolism, appetite regulation and long-term disease risk. 

The findings add another layer to scientists’ understanding of obesity, which is increasingly viewed as a condition shaped by genetics, biology, environment and behavior rather than personal choices alone.

“Obesity is not simply the result of individual choices,” Landry said. “This work highlights that obesity risk is 40 to 70 percent heritable and can be passed across generations through complex biological and environmental influences.” 

While the review highlights potential risks, it also offers encouraging news.

Researchers found evidence suggesting that some obesity-related changes in sperm may be reversible. Weight-loss interventions, including healthier lifestyle habits and bariatric surgery, have been associated with improvements in sperm health and favorable changes in obesity-linked epigenetic patterns. 

Those findings suggest that prospective fathers may have opportunities to improve not only their own health but also the health prospects of future children.

The study arrives at a time when obesity remains a growing public health challenge. According to estimates cited by the researchers, more than 250 million people in the United States could be overweight or obese by 2050. 

The influence of fathers extends beyond biology.

The study found that fathers play a significant role in establishing family routines that affect children’s eating habits and physical activity levels. Fathers’ dietary choices, exercise patterns and parenting approaches are closely linked to children’s health behaviors and obesity risk. 

Simple activities can make a difference. Active participation in meal preparation, eating together as a family and engaging in physical activity with children have all been associated with healthier outcomes. 

Researchers also emphasized that fathers’ ability to support healthy lifestyles is often shaped by broader social and economic factors, including income, food security, neighborhood conditions, workplace policies and mental health. 

The authors argue that public health efforts aimed at preventing obesity should do more to include fathers.

Among their recommendations are father-inclusive prenatal care, expanded mental health support for fathers, paid parental leave and workplace flexibility that helps parents create healthier home environments. 

“Fathers have historically been overlooked in maternal and child health research and intervention efforts,” Landry said. “Recognizing fathers as active contributors to family health creates new opportunities to improve outcomes for future generations.” 

Ultimately, the researchers conclude that tackling obesity requires a family-centered and multigenerational approach. By recognizing fathers as key partners in health promotion, they believe society can create stronger foundations for healthier children – and healthier generations to come.