Three servings a day of full-fat dairy did not add body fat, raise cholesterol or trigger insulin resistance over 12 weeks, according to a University of Toronto trial that is seeing a fresh wave of syndicated coverage this week, months after it first published — and that challenges decades of dietary advice steering people toward low-fat milk, cheese and yogurt.
The study, led by nutritional sciences professor Harvey Anderson at the Temerty Faculty of Medicine and published in The Journal of Nutrition, randomly assigned 74 adults with overweight or obesity to one of three diets: a calorie-restricted plan with little dairy; three daily servings of full-fat dairy folded into an otherwise calorie-neutral diet; or three daily servings of full-fat dairy with no specific calorie restriction. All three groups were advised to follow Canada's food guide, and researchers supplied the dairy products directly to participants in the higher-dairy groups.
No penalty, some upside
After 12 weeks, the dairy groups showed no meaningful difference in weight gain, body composition or LDL cholesterol compared with the low-dairy group, and participants showed no evidence of worsening insulin resistance. The higher-dairy groups also logged improved blood pressure readings and higher intakes of calcium, protein and vitamin D than the low-dairy group.
Dietary guidance in Canada and the United States has long favored low-fat dairy on the theory that the saturated fat in whole milk and cheese drives up LDL cholesterol. Anderson said that theory hasn't held up consistently in human trials, and pointed to the "dairy matrix" hypothesis — the idea that protein, fat and minerals bound together physically inside milk change how the body digests and uses them, blunting any simple effect from fat content alone. He cited separate research from a Temerty Medicine colleague, Kozeta Miliku, linking whole milk consumption to a lower risk of childhood obesity as further evidence that dairy fat behaves differently than fat eaten on its own.
Anderson suggested the findings could matter most for older adults, who often need to get adequate protein and micronutrients from fewer daily calories, and for whom full-fat dairy may be an efficient way to do that without the downsides long assumed.
Keep it simple, eat a variety of foods and not too much of anything.
Harvey Anderson, University of Toronto
The trial's own limits are real: it ran just three months with 74 participants, too small and short to say anything about long-term diabetes or heart-disease risk, and it was funded in part through Canada's Dairy Research Cluster 3 program. Anderson's team is calling for larger, longer trials before the finding reshapes official guidelines — and nothing here suggests unlimited full-fat dairy is risk-free, only that three servings a day didn't move the metabolic markers doctors watch most closely.
