Trend diets have often indicated that carbohydrates or fat are the main causes of America's ever-growing obesity epidemic. Atkins and keto followers will tell you that you need to cut carbs and focus on fats to find the key to rapid weight loss. Then there are those who claim you have to cut the fat of your diet to get thin.
There are several studies that support both claims, but a new Harvard review found that – as the age-old saying goes – quality matters more than quantity. The study, published in JAMA Internal Medicine, found that eating a certain macronutrient does not increase a person's risk of death, but eating unhealthy versions does.
In particular, the researchers found that a "healthy" low-carb diet consisting primarily of vegetable proteins and unsaturated fats reduced people's overall mortality risk by 9 percent. On the other hand, diets high in animal proteins and saturated fats increased mortality risk by 7 percent.
If you are on a low-fat diet, make sure you stick to whole grains and non-starchy vegetables, which reduces the risk of mortality for all causes by 11 percent. Eating low-quality carbohydrates such as white bread and sugary snacks increases the risk of death by 6 percent, the researchers found.
"The debate over the health consequences of a low-fat or low-carbohydrate diet is largely controversial unless the sources of fat or carbohydrates are clearly defined," said Zhilei Shan, postdoctoral fellow at the Harvard Department of Nutrition and lead author of the study. said in a publication.
Nearly 40,000 adults from the United States were examined for the study from 1999 to 2014. The researchers carried out regular check-ins. While some of the adults were on a low-carb or low-fat diet, eating habits did not increase or decrease their risk of mortality.
"These results suggest that the association of low-carb and low-fat diets with mortality may depend on the quality and nutritional source of the macronutrients," the study's authors write.
This study may not disprove the reported benefits of low-carb or low-fat diets, but it does mean that cooking a plate of bacon and eggs and calling it a "keto" is probably not the best idea.