Full-Fat Milk Linked to Lower Obesity in Childhood

A study shows that full-fat milk is connected to lower childhood obesity.

The study, on the International Milk Genomics Consortium’s (IMGC) website, reports that the large, longitudinal observational study found that whole milk consumption in children 5 years of age is associated with lower adiposity and obesity in middle childhood. 

Childhood obesity remains a pressing public health issue. It can lead to health problems in adulthood, including diabetes, cardiovascular disease, musculoskeletal disorders, and certain cancers.

Traditional pediatric dietary guidance in the U.S. has been to consume low-fat or fat-free dairy products, but these recommendations were extrapolated from studies involving adults.

Childhood obesity remains a pressing public health issue. According to the CDC, nearly 1 in 5 children and adolescents aged 2 through 19 have obesity in the U.S. This can lead to health problems later in adulthood, including diabetes, cardiovascular disease, musculoskeletal disorders, and certain types of cancer.

Traditional dietary guidance in the U.S. has been to consume low-fat or fat-free dairy products to help limit saturated fat intake. It wasn’t until earlier this year that the Dietary Guidelines for Americans strongly recommended full-fat dairy products.  

There is a growing body of evidence suggesting that full-fat dairy may not be as harmful as we think. One study reported that overweight adults who consumed three servings of full-fat dairy did not experience negative effects on their body weight or select metabolic markers. Another study found that consumption of whole milk lowered children’s risk of obesity in early adolescence. 

The American Academy of Pediatrics has even recommended that children only drink whole fat milk until they are about 2 years old, unless there is a reason to switch sooner, such as a family history of obesity or heart disease. The aim is to reduce childhood obesity; however, these guidelines are based on studies from adults, and children require plenty of nutrients while they are developing.

Few studies had explored how milk-fat intake affects rates of obesity in children, but new research from the University of Toronto has found that whole milk consumption in children at age 5 years is associated with lower adiposity and obesity at age 8. 

“This is regardless of the child’s socioeconomic status, ethnicity, physical activity, and other factors that influence growth,” says the lead researchers of the study, Dr. Kozeta Miliku, assistant professor in nutritional sciences; Dr. Tara Zeitoun, a post-doctoral fellow; and Zheng Hao (Howard) Chen, a PhD student at the University of Toronto. 

The team used data from the Canadian Healthy Infant Longitudinal Development (CHILD) Cohort Study, one of the largest Canadian population-based pregnancy cohort studies which has enrolled participants across 4 different sites in Canada. They assessed the children’s milk-fat intake, along with their height, waist circumference, waist-to-height ratio z-score, fat mass percentage, BMI, blood pressure, and metabolic factors at ages 5 years then 8 years. 

In addition, the research team used recent guidelines from the Lancet Diabetes & Endocrinology Commission to help define preclinical and clinical obesity in children. This definition is more stringent than that of the World Health Organization, which only measures BMI. The Lancet Commission goes beyond BMI by requiring confirmation of excess adiposity through measurements of body size or body fat mass percentage. It also considers health factors that are a result of having obesity, such as elevated blood pressure or high cholesterol. 

“BMI does not distinguish between fat and muscle mass,” says Miliku, Zeitoun, and Chen, “so a child with more muscle mass may be grouped in the same obesity category as a child with more fat mass … These nuances in obesity classification can help unmask the true effect of diet on childhood obesity development by isolating the effect of body fat mass from muscle mass.”

The researchers found that consumption of whole milk fat at age 5 years was consistently associated with a lower risk of obesity at age 8 years. The children had lower measures of adiposity including BMI z-score, waist-to-height ratio z-score, and fat mass percentage. The data highlight the importance of a more holistic approach to a healthy diet as opposed to strictly cutting out fat. 

“The findings were surprising in the sense that whole milk has traditionally been viewed as something that could contribute to excess weight gain in children because of its higher fat and calorie content,” explains Miliku, Zeitoun, and Chen. “However, our findings are also consistent with a growing body of pediatric research suggesting that whole-fat dairy may not increase obesity risk in children and may even be associated with healthier body composition outcomes.” 

“Children are not simply ‘small adults,’” the researchers add. Given that pediatric guidelines are often extrapolated from adult studies, “we may need to re-evaluate whether current recommendations fully reflect the best available evidence in children.” Indeed, this is particularly important as children continue to grow and establish eating habits that may influence their health later in life. 

The CHILD Cohort Study uniquely positions the research team to follow study participants’ health trajectories long-term. The team plans to assess whether the association between milk-fat intake and obesity persists into adolescence. They are also interested in exploring how dairy fat may influence cardiometabolic pathways and overall dietary patterns.   

Because this was an observational study, Miliku and colleagues recognize that a randomized, controlled clinical trial is needed to determine causality between milk-fat content and obesity. 

Nevertheless, “our findings contribute to the growing evidence base that can help inform future pediatric nutrition guidelines and public health recommendations.” 

IMGC is a non-profit organization that brings together leading scientists, innovators, and industry partners to advance the science of milk for human health.