Stellenbosch University study rebukes low carb, high fat diet

It has been the topic of much dinner conversation and debate recently– Professor Tim Noakes’ challenge of the low-fat, high carbohydrates diet that has been promoted by the United States Department of Agriculture since 1977. Noake’s high-protein, low-carb, high-fat way of life has speedily gained popularity in South Africa and he has reported people losing as much as 80kg within seven months of following his diet.

Tim Noakes is the director of the UCT/MRC research unit for exercise science and sports medicine in the department of human biology at UCT. The eating plan he advocated was first prescribed in 1861 by a Harley Street surgeon, Mr William Harvey, with great success to a corpulent London undertaker, Mr William Banting, thus it is more appropriately named the Harvey/Banting diet.

‘Banting’ was the standard treatment for weight loss in all the major European and North American medical schools for nearly 100 years, until it suddenly went out of fashion after 1959 and was replaced by the low-fat, high-carbohydrate diet. Health and nutrition has indeed come a long way and there isn’t a doubt that the field has become increasingly competitive with well researched and scientifically proven ways of healthy eating expanding in abundance every day.

Noakes believes the low fat diet is the direct cause of global obesity/diabetes epidemic that began in 1980. He says the casual mechanism was the replacement of fats in diet with, especially, sugar and carbohydrates which drive both overconsumption of calories (since carbohydrates increase hunger; they do not satiate) and, especially in the insulin resistant, the accumulation of body fat (since the insulin-resistant must convert most of the carbohydrate they ingest into fat). Noakes further highlights another important mechanism which appears to be the pro-inflammatory action of modern GMO wheat, especially in disputing the protective barrier function of the human gut, leading to ‘leaky gut’ syndrome.

“The key to dietary prescription is not the diet. It is the individual receiving the prescription. That small proportion of the population who are insulin- sensitive can probably prosper on a wide range of different diets. However, those who are insulin – resistant, like me, must restrict the amount of carbohydrate they eat daily,” Noakes told Longevity magazine.

Noakes says he eats 25g of carbohydrate per day and believes that eating more must produce unfavorable health outcomes for the insulin resistant, as it has in his case.

Noakes’s diet has since caused controversy globally with a number of experts constantly debating around the issue.

A recent study conducted by the Stellenbosch University which was released Wednesday night says the Low carbohydrates diets such as Noakes’s results in no more weight loss than “recommended balanced diets”.

Researchers say a balanced diet is one that “reduces energy intake by guiding healthy food choices and decreasing portion sizes, while keeping the carbohydrate, protein and fat within the recommended ranges of intake”. Balanced diets include plenty of vegetables, fruit and unrefined carbohydrates such as rice and oats, and emphasize vegetables and fish fats and oils instead of animal fats.

The study, published in online medical journal Plos One, combined the results of 19 clinical trials conducted in high-income countries, and measured weight loss and heart disease risk factors such as blood cholesterol levels. Researchers observed 3 209 overweight and obese participants for periods of between three months and two years.

According to the study, in each of the trials, the participant’s calorie intake was controlled, in other words, those on low carbohydrate diets consumed the same amount of calories as those on “balanced diets”.

“This systematic review shows that when the amount of energy (calories) consumed by people following the low carbohydrate and balanced diets was similar, there was no difference in weight loss after three to six months and after one to two years in those with and without diabetes,” said lead researcher Celeste Naude from the Centre for Evidence-based Health Care at Stellenbosch University’s faculty of medicine and health sciences.

Specialist physician and cardiologist based at Melrose Arch, Dr Riaz Motara, supports the Stellenbosch study saying the ideal nutritional plan should follow the food pyramid.

“Eating a high saturated-fat diet does not make you gain weight. But the problem with saturated fat today is that it is rich in omega-6, which increases the risk of high cholesterol levels, heart disease and stroke.” Motara told Longevity magazine.

Renowned speaker on nutritional-related topics and lecturer at the University of Pretoria, Melissa Kelly, warns about the risks of going the Noakes’s diet route.

She recognizes that for some people, those like Tim Noakes, can make the low-carb, high-fat diet work (if done correctly). She continues to highlight how ‘regular training’ is a way of life for these individuals, so much so that going an extra mile preparing good clean food has become a norm. Kelly says this might not be the same for someone who isn’t ready to change their lifestyle completely because the repercussions maybe disastrous.

“I personally believe that this is not a decision to take lightly and not a decision you can go back on; the risks are too high and the odds will then be against you.”

“The body now runs on fat as a fuel source and not carbohydrates, and soon, this person has cravings and starts to reintroduce carbs. Where a normal- functioning metabolism would not use carbohydrates to make fat, this person has now trained his body to use fat as a preferred fuel and turn all carbohydrates to fat. This is why so many people who have followed some kind of high-protein, low- carb diet gain back all the weight, plus a few extra kilos, as soon as they eat a well balanced diet again,” she continued to say.

Stellenbosch researchers say improving the diets of South Africans is an important step in preventing and managing obesity, heart disease, stroke and diabetes. They concluded by saying more research is needed before more conclusive decisions about this matter can be made.

 

Written by: Siyanda Nkala