Not all low-carb diets help you live longer

January 22, 2020 in Healthy Eating, Nutrition Topics in the News, Weight Management

Not all low-carb diets help you live longer

People who follow low-carb diets may not live longer, suggests a study from the Harvard T.H. Chan School of Public Health in Boston. It appears to depend on the foods you include in your diet.

For the study, researchers followed 37,233 adults for two decades starting when they were 50 years old, on average. During the study, 4,866 people died, or about 13% of participants. 

Overall, mortality rates were similar for people who followed low-carb or low-fat diets and those who didn’t. 

However, the risk of early death was lower for people on these diets who consumed healthier foods like plant proteins, unsaturated fats and high-quality carbohydrates such as vegetables, fruits, legumes and whole grains. In contrast, mortality was higher for people whose diets included lots of saturated (animal) fats and animal protein. 

Diet quality matters

The health benefits of a low-carb diet may depend not only on the types of protein and fat eaten, but also the quality of carbohydrate in the diet.

Among low-carb dieters, people who got the most calories from unhealthy foods were 16% more likely to die during the study period than people with the healthiest diets. 

With low-fat diets, people who got the most calories from unhealthy foods were 12% more likely to die. 

It’s not completely clear what happens in the body when people consume different types of carbs or fats that might impact longevity.

Eating lots of saturated fats, for example, might raise cholesterol, and consuming more unsaturated fats might help lower cholesterol as well as reduce inflammation. Plant based proteins also have fibre and many beneficial phytochemicals that aren’t present in animal foods. 

People who eat well may have other healthy habits that help them live longer. It’s possible they may exercise more, have lower body weight, are less likely to smoke and drink alcohol to excess. 


The study wasn’t designed to prove whether or how any specific eating habits might help people live longer, or have the opposite effect. It was an observational study that found an association only.

As well, researchers scores participants’ diet quality based on their recollection of a single day’s food intake; it’s possible some people changed their eating habits over time. Plus, participants were asked to recall everything they ate in the previous 24 hours, which is prone to error. 

Despite this, these findings add to a preponderance of data that it’s more about selecting whole natural or minimally-processed foods, regardless of the amount of carbs or fat.

Source: JAMA Internal Medicine, online January 21, 2020.

All research on this web site is the property of Leslie Beck Nutrition Consulting Inc. and is protected by copyright. Keep in mind that research on these matters continues daily and is subject to change. The information presented is not intended as a substitute for medical treatment. It is intended to provide ongoing support of your healthy lifestyle practices.