A study published in the Lancet and scheduled to be presented Tuesday at the European Society of Cardiology meeting in Barcelona aims to overturn the prevailing logic that fat is bad for you. The study tracked the diets and health of 135,000 people between the ages of 35 to 70 for about seven years from 18 countries around the world.
The the study examined medical history, health, lifestyle habits and socioeconomic status. Participants were asked to complete daily questionnaires in which they recorded the amounts of calories they were getting from the three major macronutrients: fats, carbohydrates and proteins.
The study, led by Mahshid Dehghan from the Population Health Research Institute at McMaster University in Ontario, also showed that eating fruits, vegetables and legumes can reduce your risk of dying early. Three or four servings a day are sufficient — additional servings do not necessarily benefit your health.
The study revealed that low intakes of saturated fats (below 3 percent of daily value) are associated with higher risks of death, compared to daily intakes of 13 percent.
People consuming high-carb diets (77 percent carbohydrates) had a 28 percent greater chance of dying earlier than those eating low-carb diets.
"The study showed that contrary to popular belief, increased consumption of dietary fats is associated with a lower risk of death," Dehghan said. This may be because people substitute unhealthy carbs for the fats they cut out, she noted.
"We found no evidence that below 10 percent of energy by saturated fat is beneficial, and going below 7 percent may even be harmful. Moderate amounts, particularly when accompanied with lower carbohydrate intake, are probably optimal," she added.
According to Dehghan, "the best diets will include a balance of carbohydrates and fats, approximately 50 to 55 percent carbohydrates and around 35 percent total fat, including both saturated and unsaturated fats."
Clinical investigator with the US National Institute on Aging Christopher Ramsden is skeptical that this study is the answer to the ongoing debate.
"There's a lot more information that's needed. They did a great job and they're going to have a lot more coming out of it for years to come, but it's hard to get it down to recommendations regarding food at this point," Ramsden said.
Current global guidelines recommend that 50 to 65 percent of your daily calories be derived from carbohydrates and less than 10 percent from saturated fat, but it may take some more research before those begin to change.
"[The study] really highlights the need for well-designed randomized controlled trials to answer some of these questions," Ramsden added.
Other critics claim that the study did not evaluate the specific foods that the fat and carbohydrate nutrients were coming from. According to Bethany O'Dea, a cardiothoracic dietitian with Lenox Hill Hospital in New York City, that is a "major flaw from a nutrition standpoint."
"For example, eating a healthy carb like an apple is more nutrient dense and better for you than eating a bag of processed potato chips," O'Dea said.
"Furthermore, the study did not take trans fats into account, which hold heavy evidence of being unhealthy and contributing to cardiovascular disease," she added.
"Your diet should consist of healthy carbs, lean protein, and plenty of fruits and vegetables. Remember to avoid processed snacks that contain trans and saturated fats, and opt for a healthy carb source," she explained.
