Post-analyzes, studies combining several relevant studies to arrive at a larger conclusion, are undoubtedly valuable, but that does not mean that there is not enough room for discussion of their findings.
Because their findings depend on the criteria they used to determine which studies should be included. Thus, when looking at a meta-analysis on the effect of low carbohydrate (LCD), variables that could affect outcome could include the definition of LCD (ie How many grams of daily carbohydrate are a low carbohydrate diet) the number of the databases searched, the way in which the risk of bias was evaluated and applied, and the investigation of the causes of heterogeneity, to name just a few of those found in the most comprehensive list (AMSTAR) here:
And in fact, a study analyzing the quality of meta-analyzes of low-carbohydrate diets has recently been published in Obesity Reviews and its findings are in line with my assertion that low carbohydrate diets are so good or bad any other diet, and that at the end of the day, what matters more than the prescribed diet is to maintain the diet.
The authors found that,
"low-carbohydrate (low-carbohydrate diet / LCD) meta-analyzes showed LCD superiority for weight loss while moderate quality showed inconsistent results and high quality showed little or no difference"
Of course, all of the studies examined looked at total losses between different prescriptions, but in my opinion this may not be the best way to evaluate them.
Because as DIETFITs study so elegantly illustrated, there are people who are doing extremely well with low-carbohydrate or low-fat diets, while other people are incredibly poor and all within the same study population.
I would say that this applies to any diet.
All that says, be wary of any study or meta-analysis that a diet is better than the other, and for anyone who suggests that a particular diet is not worth trying. A person's best diet is the worst of the other person.
(Photo by Jenna Hamra from Pexels)