Those of us interested in nutrition are divided into those that think that low-carb eating is the best thing since sliced bread (oops, not allowed that!) and those that consider low-carb to be "just another fad diet". Very few people seem to sit in the middle.

So when a review of low-carb diets from the Cochrane global scientific review organisation was published recently, suggesting low-carb diets had a minimal advantage over the traditional low-fat diet, it was music to the ears of the anti-low-carb brigade. They invited Professor Clare Collins from the University of Newcastle to write an opinion piece, published on The Conversation and widely quoted elsewhere. You could almost hear some critics saying "See, I told you so."

But, as is often the case in nutrition, things are not quite what they appear.

Let's have a look at what the paper said (I'm going to get a bit science-y here, so bear with me).

The massive review (456 pages long) included 61 parallel-arm randomised controlled trials (RCTs) that randomised 6925 participants to either "low-carbohydrate" or "balanced-carbohydrate" weight-reducing diets.

In the 37 trials involving overweight and obese participants without type 2 diabetes, there was an average difference of 1.07 kilograms greater weight loss in favour of low-carb diets. From this, the authors concluded that, when compared with balanced diets, low-carb diets "probably result in little to no difference in change in body weight over three to 8.5 months".

In overweight and obese participants with type 2 diabetes (14 studies), there was an average difference of just over a kilogram (1.26 kilograms) in favour of low-carb diets. The authors again concluded that when compared with balanced diets, low-carb diets "probably result in little to no difference in change in body weight over three to six months".

This week, prominent Welsh nutrition researcher Dr Zoe Harcombe published her review of the paper and highlighted a huge problem with the findings: the paper did not actually look at low-carb diets!

The generally accepted definition of a low-carb diet is a carb intake of fewer than 130 grams per day. A very low-carb intake, sometimes referred to as a ketogenic or "keto" diet, is defined as less than 50 grams per day. The definition of a low-carb diet used in this study, however, included diets containing up to 225 grams of carbohydrate per day, or 45 per cent of energy intake. So the study really looked at low- and moderate-carbohydrate diets, rather than low-carb. There is no one in the nutrition world (except for these authors) who would consider 225 grams of carbs a day as low-carb.

Fortunately tucked away at the back of the paper was some data that enabled Dr Harcombe to calculate the effect of both a very low-carb and a low-carb diet (as generally defined). The very low-carb diet produced a weight loss of 2.29 kilograms more than that of a balanced diet, while in the group with carb intake between very low-carb and low-carb (50 to 130 grams per day) there was a 1.51 kilograms greater weight loss.

All of a sudden the weight loss associated with true low-carb diets looks a whole lot more impressive!

There was another very important finding to come out of this paper that was not highlighted. In the studies where energy intake was similar for both the balanced and low-carb diets, there was only a very small difference in favour of low-carb diets. On the other hand, when both diets had no restrictions in energy intake, there was almost a three-kilogram difference in favour of the low-carb diet (2.71 kilograms).

MORE 'SILENT ASSASSIN':

This finding shows one of the major advantages of a low-carb diet: you don't need to restrict energy intake. The main reason diets that restrict energy intake (calories) fail is because you quickly become "hangry" - hungry and angry. It is very difficult to maintain an eating pattern if you are constantly hungry. And by and large, eating carbohydrates make you hungry, while eating healthy fats and proteins leaves you feeling full. So you don't tend to have the hunger problems with low-carb that you do on a low-calorie diet.

The fact that these additional results were not highlighted in the paper, and that the definition of low-carb included moderate-carb diets as well, is worrying to me. The principal author, Celeste Naude, has long been critical of low-carb diets. A paper she authored was used to build the case against noted South African clinician and researcher Professor Tim Noakes, when he was called before a professional board in an attempt to have him censured for giving low-carb advice. It came as no surprise to me that the complaint was thrown out after a high-profile "trial" covered widely by the South African media. The judge concluded there was no evidence to support the accusation that giving the advice to reduce carbohydrate intake was dangerous. Professor Noakes had himself resolved a number of health issues, including type 2 diabetes, by changing to a low-carb diet.

The nutrition world is slowly swinging around to the realisation that low-carb is the healthiest way to eat. There is now substantial scientific evidence to support its superiority over low-fat and low-calorie diets in reducing weight. A low-carb diet has also been shown to be the most effective treatment for those with type 2 diabetes, and shows promising results in the management of other chronic diseases such as inflammatory bowel disease, cardiovascular disease, arthritis, epilepsy, Parkinson's and Alzheimer's disease, polycystic ovary disease and infertility.