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 monounsaturated fat, such as olive oil and avocados, 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 polyunsaturated fats, such as the omega-3 and omega-6 fatty acids in fish and walnuts, was associated with a 13 percent reduction in total mortality and a 29 percent reduction in death from neurodegenerative diseases.
But replacing saturated fats with carbohydrates, such as sugars and refined grains, did not confer any health benefits.
“Not all fats are created equal,” said the senior author, Dr. Frank B. Hu, a professor of nutrition at the Harvard T.H. Chan School of Public Health. “We should eat more good ones from fish and avocados, instead of animal fats. And second, the low-fat, high-carbohydrate diet is not beneficial for improving health and longevity.”