The Women’s Health Initiative Dietary Modification Trial was started back in 1993, at a time when dietary fat was seen as a dietary evil and the low-fat diet was thought to be a straightforward route to preventing heart disease, some cancers, and the epidemic of obesity that was beginning to sweep the country. With funding from the National Heart, Lung, and Blood Institute, researchers recruited almost 50,000 women between the ages of 50 and 79 years. Of these, 19,541 were randomly assigned to follow a low-fat diet. Their goal was to lower their fat intake from almost 38% of calories to 20%. They were helped in this effort by a series of individual and group counseling sessions.Another 29,294 women were randomly assigned to continue their usual diets, and were given just generic diet-related educational materials.
After eight years, the researchers looked at how many (and what percentage) of women in each group had developed breast cancer or colorectal cancer. They tallied up heart attacks, strokes, and other forms of heart disease. They also looked at things like weight gain or loss, cholesterol levels, and other measures of health.
No Health Benefit to Replacing Fat With Carbs
Low-fat diets that are high in carbohydrates are unlikely to improve your health, a new study shows.
Researchers came to the conclusion after studying the eating habits and health behaviors of 126,233 men and women who completed health questionnaires every two to four years for up to 32 years. Then they calculated the effect of replacing just 5 percent of saturated fat calories with another type of fat or carbohydrates.
The study, in JAMA Internal Medicine, found that replacing 5 percent of daily calories from saturated fats (mainly animal fat) with foods high in polyunsaturated fats, such as the omega-3 and omega-6 fatty acids in fish and walnuts, was associated with a 27 percent reduction in total mortality and reduced death from cardiovascular disease, cancer and neurodegenerative disease.
A similar switch from saturated fat to monounsaturated fat, such as olive oil and avocados, was associated with a 13 percent reduction in total mortality and a 29 percent reduction in death from neurodegenerative diseases.
"Eat food. Not too much. Mostly plants."That, more or less, is the short answer to the supposedly incredibly complicated and confusing question of what we humans should eat in order to be maximally healthy. I hate to give away the game right here at the beginning of a long essay, and I confess that I’m tempted to complicate matters in the interest of keeping things going for a few thousand more words. I’ll try to resist but will go ahead and add a couple more details to flesh out the advice. Like: A little meat won’t kill you, though it’s better approached as a side dish than as a main. And you’re much better off eating whole fresh foods than processed food products.
That’s what I mean by the recommendation to eat ”food.” Once, food was all you could eat, but today there are lots of other edible foodlike substances in the supermarket. These novel products of food science often come in packages festooned with health claims, which brings me to a related rule of thumb: if you’re concerned about your health, you should probably avoid food products that make health claims. Why? Because a health claim on a food product is a good indication that it’s not really food, and food is what you want to eat.