For years, we’ve been told to switch from full-fat dairy to skim milk. The lower fat content was thought to help with weight loss and prevent diabetes. Recently, large population studies designed to look for links between full-fat dairy consumption, weight and disease risk are starting to call that recommendation into question.
The study in question, published in the journal Circulation was carried out by Dr. Dariush Mozaffarian and his colleagues. They analysed the blood of 3,333 adults enrolled in the Nurses’ Health Study of Health Professionals Follow-up Study over about 15 years. They found that people who had higher levels of three different by-products of full-fat dairy foods had on average, a 46% lower risk of getting diabetes during the study period than those with lower levels.
Dr. Mozaffarian summarises these findings by saying: “I think these findings together with those from other studies do call for a change in the policy of recommending only low-fat dairy products. There is no prospective human evidence that people who eat low-fat dairy do better than people who eat whole-fat dairy.”
Why was there a push for low-fat/skim milk in the past? The theory from the 70s was that since full-fat milk had more calories per cup and skim milk had less, the average person would lose weight and reduce the risk of diabetes by switching to skim.
Clinical studies since then have found that when people reduce how much fat they eat, they tend to replace it with sugars. This has been shown to worsen insulin and cause insulin resistance, while increasing diabetes risk overall. In the current study, Dr. Mozaffarian adjusted for the role that weight plays and found that the connection between full-fat dairy intake and lower diabetes risk remained strong despite being independent of weight gain.
Need more evidence? If you said yes, good. I have more… In fact, in a separate study published in the American Journal of Nutrition, another group was analysed for the effects of full-fat and low-fat dairy on obesity. That group consisted of 18,438 women in the Women’s Health Study. Those who consumed the most high-fat dairy products lowered their risk of being overweight or obese by 8%.
Now, the science is NOT clear on how whole fat is helping lower risk of diabetes. There are lots of theories which revolve around the idea that the fats are working on several different levels to regulate insulin and glucose. One very simple explanation is the “Crowding Out” hypothesis, where people eating more high-fat dairy products will have enough calories so they won’t feel hungry enough to need additional calories from sugary foods. Another thesis says it’s also possible that the fats in dairy may be acting directly on cells, working on the liver and muscle to improve their ability to break down sugar from food. And then, there’s the possibility that for certain high-fat dairy foods like cheese, which is fermented, that microbes may be working to improve insulin response and lower diabetes risk as well.
In the end, no one is recommending that you go out and guzzle litres and litres of fat and milk in an effort to lose weight. I think the most important takeaway from this emerging research is that there is no benefit from demonising ONE particular ingredient or one class of foods (like fats). Instead, balance and REAL clinical research to look at how these foods interact with our bodies is the call for the day.