When the long-awaited results of the Women’s Health Initiative (WHI) hit the newsstands, consumers were confounded and confused by the headlines. Low-fat diets don’t lower the risk of heart disease? The feeling among many consumers was “why even bother with a healthy diet?” But headlines rarely tell the whole story. In fact, health headlines can often mislead readers with their catchy, attention-grabbing simplicity. And in the case of the large (almost 49,000 women) and very long-term WHI study (8 years), the headlines were particularly deceptive.
One of the major goals of the WHI was to see if a low-fat diet high in fruits and vegetables and whole grains would lower the risk of heart disease in post-menopausal women. “Low-fat” was defined as 20% of the total day’s calories coming from fat. For a woman who needs 1800 calories a day, that turns out to be 40 grams of total fat. The women were taught how to lower their intakes of fat and increase fruits and vegetables, as opposed to being given pre-packaged foods. Thus, the researchers had no control over what the women selected for the eight year study. The women kept food diaries and were interviewed by the research staff to collect the information on what and how much they ate.
By the end of the study, there were no real differences in the rate of heart disease between the women in the low-fat diet group and the women in the control group. While this may seem like an open-and-shut case against a low-fat diet, it isn’t. First of all, the women in the diet change group weren’t as successful as the researchers had expected in reducing fat and increasing fruits, vegetables, and whole grains. A more appropriate conclusion might have been that people have a hard time changing their eating habits! Secondly, the diet change focused on total fat – not the “bad” fats of the saturated and Trans varieties that are more likely to raise heart disease risk.
And, there were some very encouraging findings too. When the researchers did go back and pull the data for just the women who had the diets lowest in saturated and trans fats and highest in fruits and vegetables, they found significant decreases in heart disease! Another bonus was that the low-fat diet did not increase weight as proponents of Adkins-type high protein diets have always warned.
So what should consumers do? The bottom line nutrition advice is still the same – and the research does support it:
• Choose fats wisely, focusing on plant fats like vegetable oils, nuts, and seeds.
• Eat lots of fruits and vegetables. Five or more servings a day is a baseline for good health, but nine servings a day should be a goal! (USDA)
• Eat at least three servings of whole grains per day replacing as many refined grains with products that list a “whole” grain first on the ingredient list.