For decades, health guidelines have pushed consumers toward fat-free and low-fat dairy products, warning that the saturated fat in whole milk, cheese and yogurt could raise cholesterol and harm the heart.

A study is challenging that advice, finding that adults who ate full-fat dairy every day for 12 weeks saw no negative effects on their weight, body fat or cholesterol—and even gained some health benefits along the way.

The study, led by University of Toronto professor Harvey Anderson and published in The Journal of Nutrition, found that people who consumed three servings of full-fat dairy a day did not experience meaningful increases in weight, body fat, cholesterol or insulin resistance compared with those on a low-dairy diet.

They also had improved blood pressure and took in more calcium, protein and vitamin D.

The study was supported by Dairy Research Cluster 3 under the Canadian Agricultural Partnership AgriScience Program.

‘More Than the Sum of the Isolated Nutrients'

Anderson told Newsweek that dairy's structure may explain the results.

"With dairy products, it's got two proteins—casein and whey—that are bound together with fat and with nutrients mixed in," he said.

He added that this complex physical structure is responsible for a slow, steady delivery of nutrients from dairy, which expands its health impact to more than just the sum of the isolated nutrients.

Jessica Corwin, a registered dietitian, weighed in on the findings, telling Newsweek that they bring important nuance to long-standing dietary advice.

"For those of us raised in the fat-free era, we fully understand the negative impact this has on cravings, satisfaction and weight," she said.

She noted the study does not prove full-fat dairy is healthier than low-fat dairy, but it does undercut the assumption that adding full-fat dairy to an otherwise healthy diet will cause weight gain or worsen heart-related health markers.

Corwin added that the results point to a broader lesson about nutrition science.

"We can't always predict the health effects of a whole food by isolating one nutrient within it," she said. "Dairy contains saturated fat, but it also provides high-quality protein, calcium, potassium and other nutrients within a complex food matrix…A reminder of why whole foods remain the optimal choice over a narrow supplement."

Researchers had recruited 74 adults classed as "overweight" or "obese" and split them into three groups. One followed a low-dairy, calorie-restricted diet. A second followed an energy-neutral diet that included three servings of dairy a day. A third ate an unrestricted diet that also included three daily servings of dairy.

All participants were guided by Canada's food guide, and those in the dairy groups were supplied with full-fat dairy products for the study's duration.

Dietary guidelines in Canada and elsewhere have long encouraged low-fat dairy because saturated fat has been linked to higher cholesterol and cardiovascular risk. But researchers say the new results support what's known as the "dairy matrix hypothesis"—the idea that the physical structure of a food shapes how its nutrients are digested and absorbed, meaning a food's health effects may hinge on how its components interact rather than on any single nutrient in isolation.

Reference

Anderson, H. G., et al. (2026). The Effect of Three Daily Servings of Full-Fat Dairy for 12 Weeks on Body Weight, Body Composition, Energy Metabolism, Blood Lipids, and Dietary Intake of Adults with Overweight and Obesity. The Journal of Nutrition. https://doi.org/10.1016/j.tjnut.2026.101373.

Contact Newsweek editors on this story: Charlotte Nisbet and James Debens