Low-carb diet may make you unhealthy, shorten your life: study

Updated

Eating a high-protein, low-carb diet could actually make you unhealthy and more likely to die younger, a landmark Australian study has found.

The three-year study by the University of Sydney's Charles Perkins Centre found that while high-protein diets might make you slimmer and feel more attractive, the best diet for longevity is one low in protein and high in carbohydrates.

Professor of geriatric medicine David Le Couteur from Sydney's Anzac Research Institute was part of the team which modified the diets of 900 mice with dramatic results.

"If you're interested in a longer life span and late-life health, then a diet that is low in protein, high in carbohydrate and low in fat is preferable," he said.

"You can eat as much of that as you like.

"You don't have to be hungry, you don't have to reduce your calorie intake, you can just let your body decide what the right amount of food is."

The team put mice on 25 different diets, altering the proportions of protein, carbohydrates and fat.

The mice were allowed to eat as much food as they wanted to more closely replicate the food choices humans make.

"The healthiest diets were the ones that had the lowest protein, 5 to 10 to 15 per cent protein, the highest amount of carbohydrate, so 60, 70, 75 per cent carbohydrate, and a reasonably low fat content, so less than 20 per cent," Professor Le Couteur said.

Sorry, this video has expired Video: Professor David Le Couteur discusses his findings (ABC News)

"They were also the diets that had the highest energy content.

"We found that diluting the diets to reduce the energy intake actually made the animals die more quickly."

The mice that ate a high-carbohydrate, low-protein diet lived about 50 per cent longer than those on the low-carb diet.

"The animals that were eating the less calories had shorter life spans," Professor Le Couteur said.

"The maximum life spans vary between 100 weeks and 150 weeks, depending upon the diets.

"So there was a 50 per cent increase in life expectancy depending upon the diets that you went on, so it was a big effect."

High-protein, low-carbohydrate diets like the Atkins diet and Paleo craze are popular among people wanting to lose fat.

But Professor Le Couteur says restricting calories may not do you favours later in life.

"What we did find is in late mid-life, when we analysed their health, the animals on the best diet, the low-protein, high-carbohydrate diets, had better blood pressure, had better LDL cholesterol, had better glucose tolerance, less diabetes and so on," he said.

Professor Le Couteur says plenty of data in humans already exists that shows people who choose a high-protein diet have worse outcomes in terms of death and disease.

"Certainly we found and we expected to find that high-protein diets led to weight loss and led to increased muscle bulk, but this was associated with worse outcomes, whether it was blood pressure or diabetes or life span," he said.

The study was published in the journal Cell Metabolism.

Topics: diet-and-nutrition, health, sydney-2000, australia

First posted