I have written numerous posts on low-carbohydrate diets and have also cited studies carried out by the Cochrane initiative, possibly the most important in terms of systematic reviews on health, on numerous occasions. So it was imperative that I publish a post dedicated to the new Cochrane review on the effectiveness of low-carbohydrate diets for weight loss and health indicators, compared to high-carbohydrate diets (45-65% of energy from carbohydrates and what they call “balanced carbohydrates”)
The work was published a couple of days ago under the title “Low-carbohydrate diets or balanced-carbohydrate diets: which works better for weight loss and heart disease risks?” (2022) and as Cochrane contributors have a good habit of making summaries in “normal” language, I am going to limit myself to translating some of its most significant fragments.
There they go:
“The aim was to investigate whether low-carbohydrate diets were better than carbohydrate-balanced diets for weight loss and heart disease risk factors in overweight or obese adults (…,) as well in people with and without diabetes. type 2.
We found 61 trials involving 6925 overweight or obese people. The largest trial was in 419 people and the smallest in 20 people. All but one of the trials were conducted in developed countries around the world and almost half were conducted in the USA. Most of the trials (36) were conducted in people who did not have heart disease or risk factors. Most people (5118 people) did not have type 2 diabetes. The average starting weight of people in the trials was 95 kg. Most of the studies (37) lasted six months or less; and the longest studies (6) lasted two years.
Low-carbohydrate diets probably result in little or no difference in weight loss in the short term (trials lasting 3 to 8.5 months) and long term (trials lasting one to two years) compared with low-carbohydrate diets. balanced carbohydrates, in people with and without type 2 diabetes. In the short term, the average difference in weight loss was about 1 kg, and in the long term, the average difference was less than 1 kg.
People lost weight on both diets in some trials. The amount of weight lost on average varied widely between the two diets in different trials, from less than 1 kg in some trials to around 12 kg in others in the short and long term.
Similarly, low-carb diets for up to two years likely result in little or no difference in diastolic blood pressure, glycosylated hemoglobin (HbA1c), and LDL cholesterol (“unhealthy” cholesterol).
It was not possible to draw conclusions about unwanted effects because very few trials included them.
(…)
There is probably little or no difference in weight reduction and changes in cardiovascular risk factors up to two years of follow-up, when overweight and obese participants, with and without type 2 diabetes, are randomized to diets low in carbs or balanced carbs.”
In summary, we can interpret these results in two ways, depending on our expectations and previous ideas: One positive, seeing that low-carbohydrate diets work at least as well as high-carbohydrate ones. And another negative, considering that low-carb diets are not significantly better than high-carb ones.
If any of the readers want to delve into the investigation, in this link you can find the complete review and know the details and nuances that you consider appropriate.