New research from the University of Toronto suggests that children who drink whole-fat milk in early childhood may have lower odds of obesity in middle childhood than those who drink reduced-fat milk.
The study adds to emerging evidence that lower-fat milk does not reduce child obesity , even though many dietary guidelines in the last three decades have encouraged low-fat dairy, including Canada's dietary guidelines from 2019.
"The most important learning from this study is that whole milk was not associated with higher adiposity or obesity risk in children, and may even be linked to healthier growth patterns," says Kozeta Miliku, an assistant professor of nutritional sciences in U of T's Temerty Faculty of Medicine and a researcher at the Joannah & Brian Lawson Centre for Child Nutrition .
The study, published in the American Journal of Clinical Nutrition , is one of the largest and most comprehensive to look at milk consumption and measures of obesity in children over a period of years.
The researchers, including former postdoctoral fellow Tara Zeitoun and doctoral student Zheng Hao Chen, used data from the CHILD cohort study - a prospective study that includes health information and metrics on thousands of children from before birth to adolescence.
Caregivers reported the fat content of milk their children consumed (skim, one per cent, two per cent or whole fat). Researchers collected measures at ages five and eight, including body mass index (BMI), waist-to-height ratios, fat mass and derived preclinical and clinical obesity status.
The study authors found that over 90 per cent of children consumed milk before age five, with 24 per cent of these children consuming whole-fat milk, and about half of all children in the study drank less than one cup per day. But even with that modest consumption, children who drank whole milk at age five had significantly lower BMI and 69 per cent lower odds of living with obesity at age eight compared to children who consumed skim milk.
The researchers also observed a pattern in which higher milk fat content was associated with better measures of adiposity, or the accumulation of body fat, in children.
The findings call into question previous public health messaging on milk fat. Health Canada guidelines from before 2019 recommended that children who drink milk switch from whole- to reduced-fat milk at age two. Dietary Guidelines for Americans 2020-2025 took a similar position, but this year the U.S. Whole Milk for Healthy Kids Act allowed full-fat milk in school lunches, in line with new U.S. national guidelines that encourage full-fat dairy.
"Switching to lower-fat milk has been about cutting fat in the diet, but that may miss the bigger picture," says Miliku. "When we think about healthy growth, it's important to consider the overall nutritional context. Removing fat does not automatically make skim milk a healthier choice for children."
The research team did not examine how whole milk could reduce risk of obesity. However, they hypothesize that milk fat may improve satiety, thus reducing calorie intake from nutrient-poor foods and may also affect energy balance and metabolic pathways related to growth and nutrition.
Miliku says more research is needed to understand the mechanisms at play and to learn if the obesity-protective effect of whole milk in early childhood continues into adolescence and adulthood.
And, with little guidance about milk consumption for children in Canada's 2019 dietary recommendations, Miliku hopes the findings will help inform conversations among parents, clinicians and policymakers.
"Whole-fat milk can be part of a healthy diet and does not on its own increase obesity risk," she adds. "And it's important to think about the overall quality of the diet - the fruits and vegetables, whole grains and protein-rich foods they consume."
The research was funded by the Canadian Institutes of Health Research and U of T's Joannah & Brian Lawson Centre for Child Nutrition (made possible through a donation by President's Choice Children's Charity).
