A new study has been published in the end of last week comparing a low fat versus a low carb diet. The participants' diet consisted of either complex carbohydrates or healthy fats. The scientists have concluded that in one year there was no statistical difference between the people following either of the diets. Considering the participants involved, the topic and the results it is no wonder that this study was all over the media immediately. So let's discuss about it a bit.
Why is this study important?
This study is a randomised controlled diet. This means that the scientists were looking at the effect of the diet by standardising all the factors that could influence the results. So participants characteristics, protein content, starting BMI (33) , exercise, smoking etc were all taken into consideration. Also, this study was large. It involved many participants who the researchers followed up for a year which is a long time for studies looking into dietary interventions. It is also worth noting that the study looked at specific gene mutations (polymorphisms) that could predispose individuals to metabolise more effectively carbohydrates or fats and it also looked at an indicator of insulin resistance.
What were the results?
The results showed an average of 5 kg weight loss in a year in both groups and no difference in body composition between the two groups. There was, also, no significant change in insulin levels in any of the two groups but cholesterol and triglyceride levels were statistically lower in the group who consumed a lower carb diet. Both groups increased the consumption of either fats or carbs in time but still maintained a relatively low consumption. There was no difference in weight loss between the group who consumed the diet matched to their polymorphisms and the group that consumed a diet "against" their genotype.
What does this study mean for public health?
Basically, it tells us that there is no reason to promote a specific type of diet. The old fashioned advice of consuming a varied healthy diet and promote healthy fats and complex carbohydrates still stands. If weight loss is of concern increasing your energy expenditure and being more mindful about energy intake could actually have the same effect in the long term as a very restrictive diet. So basically just confirming what we already knew.
What does this study mens for the individual?
I believe these kind of studies can show a person how stressing about quick weight loss may actually hinder their progress. The weight loss during a year in both groups was moderate, especially considering the support both groups received in this time. Actually, small dietary and lifestyle changes could have the same results without the psychological stress of following a very restrictive diet. A healthcare professional could identify areas in your diet where small improvements would benefit your health greatly. So don't hesitate to ask for support.
What does this study mens for scientists?
I think this study set high standards when it comes to doing research on dietary interventions. There might have been weaknesses, all studies have flaws, but nothing that would greatly affect their results. In general randomised controlled diets as the "golden" studies and nutrition research is in need of more. Hopefully, more funding and subsequently more studies will follow. I personally really enjoyed reading this study and I was particularly interested in the nutrient-genes interactions. I hope future studies will explore these potential associations further. I do need to highlight though that even though the two groups consumed either good quality fats or complex carbohydrates, there was no third group to compare a diet of "lower quality". Therefore, media claims that fat or carb content doesn't matter as long as the diet is healthy may be true but are not relevant to the outcomes of this study. Maybe to the next one? It is important though to try and report science how it is and not misguiding the reader.