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What We Do Not Know About Weight Loss



Controversies in ObesityIn our exhaustive review of the potential health benefits of intentional long-term weight loss, published in Annual Reviews in Nutrition, I discussed in yesterday’s post, we also noted a number of issues that remain unresolved.

These include:

  1. The precise definition of success in terms of weight loss remains controversial, and the dogmatic assumption that prolonged periods of sustained weight loss (greater than 10 years) are more likely than shorter periods to have a beneficial effect on health out- comes has never been challenged.
  2. Some evidence suggests that intentional weight loss may lead to meaningful reductions in several conditions, such as COPD, and cancer risk with a short latency time, although data from randomized trials are not yet available to support this hypothesis.
  3. Future studies on the relationship between long-term weight loss and suicide are needed, especially in diverse populations, subgroups of patients, and those who engage in other long-term weight-loss strategies apart from the use of antiobesity medications and bariatric surgery. The potential relationship between failed weight-loss attempts and suicide ideation needs to be evaluated.
  4. There is ongoing controversy over the findings from epidemiological studies on the relationship between weight loss and mortality. Data from controlled studies in this regard are very limited.

Clearly, as we discussed at length here at the ongoing Canadian Obesity Network’s Obesity Research Summer School (Boot camp), much remains to be done for young researchers planning a career in this field.

@DrSharma
Kananaskis, AB

3 Comments

  1. Dear Dr.Sharma/lieber Dr.Sharma,

    Are there any studies to whether obese are more likely to lose with predominantly visceral fat weight / keep as obese with subcutaneous fat distribution?
    If so, is there also a difference in this regard after bariatric surgery?

    in German:
    Gibt es Untersuchungen dazu ob Adipöse mit vorwiegend visceralem Fett eher Gewicht verlieren/halten können als Adipöse mit subcutaner Fettverteilung?
    Wenn ja, gibt es diesbezüglich auch einen Unterschied nach bariatrischen Eingriffen?

    Astrid Näkel
    (MD, FÄ für Innere Medizin)

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    • If you are asking if it is easier for people to with visceral obesity to lose weight and keep it off, I am not aware of a good study that has looked at this. The general “opinion” is that it is easier to “mobilize” visceral fat than subQ fat depots (especially with physical activity) – If any reader knows of a good study that addresses this issue, I’d love to know about it.

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  2. Two comments:

    1. I would like to pull out and emphasize the following: “The potential relationship between failed weight-loss attempts and suicide ideation needs to be evaluated.” Amen! Our culture of weight-loss mania pushes many people to lose weight (which just about anyone can do). But then they are hung out to dry (and regain) because no one has figured out maintenance to any significant degree for the broad population. Long-term weight-loss maintainers are (lucky?) outliers. The lack of attention in the media given to the horribly limited success of maintenance causes people who regain to blame themselves and causes others to judge them in an extremely mean spirit way. Of course it can lead to suicide ideation (and actual suicide). I would call the dearth of good information on maintenance a media conspiracy to perpetuate the Eat-Less-Move-More lie, but that’s probably over-reach. Mainstream journalists are just lazy shmoze who refuse read an iota of the research that contradicts their pre-conceptions, which are based on 1970s mythology about weight control.

    2. In my opinion, the “ongoing controversy” about weight and mortality is the result of fat bias on the part of those who refuse to accept the results of the best unbiased research, Flegal et. al. “Excess Deaths Associated with Underweight, Overweight, and Obesity” published in JAMA, April of 2005. Simply, the Flegal team looked at who was dead ten years after being surveyed by NHANES. You were least likely to be dead (from any cause) if your BMI was 27.6. It created a U curve on either side so that people who had low (but in the “normal” range) BMIs were as likely to be dead as people with BMIs in the Obese range. This makes sense. If a person contracts cancer or another body-wasting disease, and their BMI is an “overweight” 27.6, they’re going to have more reserves to fight with than someone who contracts cancer who has a “normal” BMI of 18.5. In other research they call this the “obesity paradox.” Let’s connect those dots between the Flegal team data and the proven “obesity paradox” already. People who argue against Flegal et. al. torture the data by eliminating subsets of people who then skew the data the way they want to see it (privileging trim people). They introduce error and bias.

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