Reacción a "The treatments have leveled off cholesterol and blood pressure levels in adults over 40 with and without obesity, according to a study"

It is a fairly robust and ambitious study in terms of scale: it combines data from nearly one million people in seven countries over more than three decades, something unusual in this type of research. The methodology is well explained, and we commend the authors for their honesty in acknowledging several of their own limitations.

The main finding—that the blood pressure and cholesterol levels of older adults with obesity are increasingly similar to those of people of normal weight, thanks in large part to increased medication use—is consistent with what we already knew about the advancement of pharmacological treatment in recent decades. It is not an unexpected finding, but it does provide a useful quantification of the phenomenon.

However, caution is advised, as the study only measures two of the many mechanisms by which obesity influences health (blood pressure and cholesterol); it does not analyze inflammation, insulin resistance, diabetes, joint problems, or some types of cancer, which are also linked to excess weight. Furthermore, this improvement is only observed in people over 40: in young people with obesity, the metabolic risk remains significantly higher than in those of normal weight.

[Regarding potential limitations] The study uses BMI (Body Mass Index) to define obesity, but health professionals have long pointed out that this measure is insufficient to assess the true risk induced by obesity: it does not distinguish between fat and muscle, nor does it indicate where that fat accumulates (which is clinically the most important factor), and the study also does not include any data on the participants' diets. This means we cannot know for sure how much of the observed improvement is actually due to the medications and how much to other unmeasured factors.

In addition, they use the same BMI thresholds to classify obesity in all countries, even though it is known that, for the same BMI, Asian populations tend to have more body fat and a higher cardiometabolic risk than Western populations. This may make it difficult to fairly compare the results between different countries, such as Japan and the United States. In fact, cases of severe obesity in the Asian countries included in the study are so rare (less than 2-3% of the population) that many of these estimates had to be excluded or are unreliable. Furthermore, a potential survival bias is likely (people with severe obesity and poorer metabolic health die earlier and are not surveyed in their later years), adding uncertainty to this specific part of the study. Therefore, in the group of older adults with obesity in general, some of the observed improvement could be due to a selection effect: people who reach advanced ages with obesity and a poorer metabolic profile are more likely to have died earlier, so the survivors who enter the study might be biased towards the healthiest within that group.

Another potential limitation is that the study only records whether or not the person is taking medication, but not the intensity or type of treatment. This makes the estimates of improvement approximate, not a direct causal link. The use of other possible statistical tests to estimate the impact of different drugs could have been considered, among other possible suggestions.

Finally, the article does not detail how many people each country contributes to the overall results. That is, it indicates the total sample size used, but without specifying the representation from each country, it is difficult to assess whether the findings are dominated by one or two countries with larger samples (such as the US or England). While it is true that the appendices contain additional information on BMI ranges and age groups, etc., it would be advisable to include this information in the main article for optimal reading and evaluation.

In conclusion:

These results could be good news regarding the control of blood pressure and cholesterol in older adults with obesity thanks to medical treatment, but they cannot be considered a sign that obesity is no longer a health problem, and the results should be read with these methodological nuances in mind.