Skim milk or whole? Non-fat yogurt or full-fat? For decades, public health officials have treated these decisions as no-brainers. Cut the dairy fat, they’ve maintained, and you’ll sidestep calories without missing out on good stuff like calcium and protein. Win-win. But they might have been wrong, a chorus of experts now say.
A recent review published in the European Journal of Nutrition of the existing research on dairy fat came to some surprising conclusions: People who eat full-fat dairy are no more likely to develop cardiovascular disease and type 2 diabetes than people who stick to low-fat dairy. When it comes to weight gain, full-fat dairy may actually be better for you, the review found.
“In terms of obesity, we found no support for the notion that low-fat dairy is healthier,” says Dr. Mario Kratz, first author of the review and a nutrition scientist at the Fred Hutchinson Cancer Research Center in Seattle. Of the 25 studies included in his team’s review, Kratz says 18 reported lower body weights, less weight gain, or a lower risk for obesity among full-fat dairy eaters. The other seven studies were inconclusive. “None of the research suggested low-fat dairy is better,” he says.
More research supports his team’s findings. A 2013 study in the Scandinavian Journal of Primary Health Care tracked the dairy intake and obesity rates of more than 1,500 middle-aged and older adults. Those who frequently ate full-fat butter, milk, and cream had lower obesity rates than those who eschewed dairy fat. “Based on my own research and on the research of others, I believe high-fat dairy is less likely to contribute to obesity that low-fat dairy,” says Dr. Sara Holmberg, first author of the study.
The belief that fat isn’t a health villain has been gaining traction the last few years, especially as data has piled up showing that low-fat diets don’t work. And while national health organizations seem to be softening their stance on fat, they still recommend reaching for low- or non-fat dairy at the supermarket.
Their justification: “Research has shown consistently that nutrient-rich foods—that is, foods that pack a lot of micronutrients into every calorie—are healthier,” says Isabel Maples, a registered dietitian and spokesperson for the Academy of Nutrition and Dietetics. Maples says reduced-fat dairy provides calcium, potassium, and other good things Americans need in their diet, and does so with fewer calories than full-fat dairy. She says reduced-fat dairy also contains less saturated fat.
Kratz doesn’t disagree with Maples’s comments. But he says they make assumptions about dairy that aren’t backed up by existing evidence. “Data should be weighed more heavily than assumptions,” he says. “And the data don’t support the notion that eating full-fat dairy is worse for your health than reduced-fat or non-fat dairy.”
How could something with more calories be better for your waistline? Some researchers argue that not all calories are equal—especially when it comes to weight gain. Also, focusing on calories-per-serving largely ignores a mammoth factor when it comes to obesity: fullness. Kratz says the fatty acids that are stripped out of reduced-fat dairy may help you feel full sooner and stay full longer—meaning you’ll eat less now and in the coming hours.
Dairy’s fatty acids may also play a role in gene expression and hormone regulation. In simple terms, these acids may crank up how much energy your body burns, or limit the amount of fat your body stores. “We don’t know any of these things for certain,” Kratz adds. “But they could help explain why our findings show full-fat dairy consumption is preferable to low-fat when it comes to a person’s risk for obesity.”
Holmberg, the author of the Scandinavian study, calls dairy “paradoxical,” and says it’s not possible to judge dairy’s health effects based only on its macronutrient content. “It is important to study the effect of real food and not just nutrients,” she adds.
Several more European studies have suggested similar links between full-fat dairy and lower rates of obesity, heart disease, and diabetes. And a just-published review from the journal BMJ concludes that, back in the 1970s—when health regulators established national diet guidelines that encouraged people to avoid fat—there wasn’t evidence to support those warnings. Basically, the foundation for all your “fat is evil” beliefs may have always been weak.
At the same time, none of this means you should gorge yourself on full-fat dairy. “We shouldn’t swing the pendulum too far in the other direction and say, ‘Put butter in everything and eat as much dairy as you want,’ ” Kratz warns. (Compared to many foods—especially vegetables and fruit—dairy contains no fiber, which is critical for digestion, for how the body manages sugar, and which plays an important role in maintaining a healthy weight.)
But if you’re deciding between skim milk and whole milk, the existing research argues you may be better off grabbing the full-fat stuff.