Can low-carbohydrate or low-fat diets prolong life in middle-aged and older adults?

Short-term clinical trials have shown the health benefits of low-carbohydrate diets

ISLAMABAD, (Online) - Diets low in fat and carbohydrates can improve the health of middle-aged and older adults, a new study is reporting.

Short-term clinical trials have shown the health benefits of low-carbohydrate diets and low-fat diets for weight loss and heart health.

The new study, published in the Journal of Internal Medicine, examines the effects of those diets on mortality in middle-aged and older adults.The study looked at 371,159 people, aged 50 to 71 years. Over the study’s 23-year period, 165,698 of those subjects died.

The researchers reported that healthy low-fat diets — characterized by a low intake of saturated fat and high intakes of plant protein and high-quality carbohydrates — was associated with fewer deaths from all causes, including cardiovascular diseases and cancer.

In contrast, a general low-carb diet and an unhealthy low-carb diet were associated with significantly higher total, cardiovascular, and cancer mortality rates. However, a healthy low-carb diet was associated with slightly lower death rates.

“Our results support the importance of maintaining a healthy [low-fat diet] with less saturated fat in preventing all-cause and cause-specific mortality among middle-aged and older people,” the study authors wrote.

Carbohydrates and fats as you age

Experts agree that low-carb diets are usually best for people as they get older.

However, when it comes to fat, they say it’s important to not exclude all fat and carbs – just the fat and carbs that are unhealthy.

Kailey Proctor, a dietician specializing in oncology nutrition at City of Hope Orange County Lennar Foundation Cancer Center in California, told Medical News Today it’s important to define a healthy carbohydrate or healthy fat versus an unhealthy one.

“I see cancer patients every day and many people are unaware of the difference between simple and complex carbohydrates, along with saturated and unsaturated fats,” Proctor said. “Eating complex carbohydrates, such as whole wheat bread, quinoa, brown rice, sweet potatoes, can be beneficial. These foods are all high in fiber, antioxidants, (and) micronutrients, compared to simple carbs, such as white bread, breakfast cereals, pastries which have almost no nutritional value.”

Breaking down low-carb, low-fat diets

Trista Best, a registered dietitian for Balance One Supplements, told Medical News Today that both diets have been shown to have health benefits for middle-aged people.

However, the specific benefits may vary depending on the individual and the type of diet.

For example, some low-carb diets promote protein and the right kind of fat intake.

“It’s important to note that not all carbs are created equal and some healthy carbohydrates like fruits, vegetables, and whole grains can be an important part of a balanced diet,” Best said.

“Low-fat diets, which typically restrict fat intake and emphasize carbohydrates and protein, have also been shown to have health benefits, including improving cholesterol levels and reducing the risk of heart disease,” she added. “However, it’s important to choose healthy fats like those found in nuts, seeds, avocado, and fatty fish.”

Robert Lafelice is a registered dietician for fitness company Set For Set. He told Medical News Today looking at a healthy diet through an evolutionary lens makes it easy to understand.

“The preponderance of evidence clearly favors a low-carb diet for all adults,” Lafelice said. “Humans evolved over hundreds of thousands of years on a diet dominated by protein and fat, not carbs. The government recommendation of eating over half of our calories from carbs is the antithesis of the original human diet.”

Lafelice added that a high-carb diet can be traced to everything from diabetes to cancer to dementia. He also said low fat diets alone aren’t necessarily healthy.

“There are essential fatty acids and amino acids (protein), but there are no essential dietary carbs,” he said. “With regard to older adults, eating low fat (and) high carb is especially unhealthful and dangerous. As we age, we naturally become more insulin resistant. So, eating lots of carbs will only exacerbate this.”

Diets in middle age

Heather Dyc, a nutritionist and writer, told Medical News Today she’s a “big fan of low carb, but not low fat, diets for the middle aged.” “Good fats – omegas – have so many health benefits for aging people, it might do more harm than good to cut these out of your diet,” she said. “For example, they help slow cognitive decline, improve mood, and may help ward off metabolic disease. Fats from healthy sources – nuts, seeds, fish, olive oil – are also very filling, meaning you’ll eat fewer calories. This is beneficial because middle-aged people tend to have more belly fat than their younger counterparts.”

Dyc said middle-aged years are a good time to be picky about where carbs come from.

“(The) 40s and 50s is the time when our metabolism slows and hormone production drops,” she said. “It’s easier to gain weight and we experience more aches and pains than usual. Nutrient-dense fruits and vegetables contain fiber, antioxidants, and vitamins and minerals that help us age gracefully.”