Which diet is better? Low-carb or low-fat?

Fans of trendy low-carb diets include Kim Kardashian and Gwyneth Paltrow. Photo / Getty Images

Trendy low-carb diets are no better for weight loss than those that cut out fat, new research claims.

Many celebrities, including Kim Kardashian, Megan Fox and Mick Jagger, have found weight loss success by eating a low-carb, high-fat diet, dubbed the keto diet.

But a new study found that people who cut either carbs or fats shaved off about 5.9 kg (13 pounds) of excess weight in about the same proportion, reported The Daily Mail.

Although no diet is better than another, researchers say the fundamental strategy for weight loss is consuming less sugar, less refined flour and eating more vegetables.

"We've all heard stories of a friend who went on one diet - it worked great - and then another friend tried the same diet, and it didn't work at all," said Dr Christopher Gardner, a professor at Stanford University School of Medicine.

"It's because we're all very different, and we're just starting to understand the reasons for this diversity. Maybe we shouldn't be asking what's the best diet, but what's the best diet for whom?"

For the study, researchers led by Gardner recruited 609 men and women between the ages of 18 and 50 and placed them into one of two dietary groups: low-carbohydrate or low-fat.

They monitored the progress of the subjects for 12 months by measuring weight, body composition, baseline insulin levels and how many grams of fat or carbohydrate they consumed daily.

In the initial eight weeks of the study, participants were told to limit their daily carbohydrate or fat intake to just 20 grams, which is about what can be found in a 1.5 slices of whole wheat bread or in a generous handful of nuts, respectively.

After that they added back five to 15 grams of fat or carbs gradually, aiming to reach a balance they believed they could maintain for the rest of their lives.

They were also urged to consume healthy low-fat and low-carb diets, as opposed to bacon, which is low in carbs, or soda, which is low in fat.

"We made sure to tell everybody, regardless of which diet they were on, to go to the farmer's market, and don't buy processed convenience food crap," Dr Gardner said.

By the end of the study, participants in the two groups had lost, on average, 13 pounds (5.8kg).

The findings, published in JAMA today, also showed variations with participants losing up to 60 pounds (27kg) in a year while others actually gained weight.

Researchers also homed in on genetics to discover if biology would encourage an individual's body to favour a low-carbohydrate diet or a low-fat diet, but they found no associations between gene patterns and a propensity to succeed on either diet.

"This study closes the door on some questions - but it opens the door to others. We have gobs of data that we can use in secondary, exploratory studies," Dr Gardner said.

He added that the best way to lose weight is to eat less sugar, consume more vegetables, and go for whole food, whether that is a wheatberry salad or grass-fed beef.

"On both sides, we heard from people who had lost the most weight that we had helped them change their relationship to food, and that now they were more thoughtful about how they ate," said Gardner.

The difference between good carbs and bad carbs:

Bad Carbs:
• White pasta
• Sugar-sweetened beverages
• Pastries
• White bread
• White rice

Good carbs:
• Whole grain pasta
• Brown rice
• Vegetables
• Fruits
• Beans
• Whole wheat flour