Nutrition science is full of contradictions. Now there may be one more paradoxical dietary rule to keep you perpetually confused: full-fat diary products may help you keep the pounds off.
That's according to two new studies that found those who enjoyed a relatively high intake of whole-fat milk, butter and cream were less likely to be obese than those who stuck to a more moderate dairy fat diet or rarely ate high-fat dairy.
In one paper, published by Swedish researchers in the Scandinavian Journal of Primary Health Care, middle-aged men who consumed high-fat milk, butter and cream were significantly less likely to become obese over a period of 12 years compared to men who never or rarely ate high-fat dairy.
Yep, that's right. The butter and whole-milk eaters did better at keeping the pounds off.
The second study, published in the European Journal of Nutrition, is a meta-analysis of 16 observational studies. There has been a hypothesis that high-fat dairy foods contribute to obesity and heart disease risk, but the reviewers concluded that the evidence does not support this hypothesis. In fact, the reviewers found that in most of the studies, high-fat dairy was associated with a lower risk of obesity.
What's the reason?
It's not clear what might explain this phenomenon. Lots of folks point to the satiety factor. The higher levels of fat in whole milk products may make us feel fuller, faster. And as a result, the thinking goes, we may end up eating less.
Or the explanation could be more complex. "There may be bio-active substances in the milk fat that may be altering our metabolism in a way that helps us utilize the fat and burn it for energy, rather than storing it in our bodies," says Greg Miller, executive vice president of the National Dairy Council.
Previous studies have found that this puzzling pattern holds true for children.
And while other studies have suggested a link between high-fat dairy and heart disease, these latest studies found no consistent association between the two. They did find, however -- as previous research has -- that eating low-fat yogurt lowers rates of diabetes risk, whereas high-fat dairy had no correlation.
So, where does this leave us, the rule-followers, who have complied with the skim-milk-is-best edict?
Well, opinions differ. The recommendations that led to the fat-free dairy boom were, in part, born out of concerns about cholesterol. Whole-milk dairy products are relatively high in saturated fat. And eating too much saturated fat can increase the risk of heart disease. So many experts would agree that adults with high cholesterol should continue to limit dairy fat.
But it's also becoming clear that there are benefits to full-fat dairy too, at least for some consumers.
In addition to the body weight association, organic whole milk contains beneficial omega-3 fatty acids. However, the bioactive properties of dairy fat varies from product to product, scientists say. As such, more studies are needed to understand exactly what's going in the bodies of high-fat dairy users that helps them keep the weight off.