Being overweight reduces risk

[Orangeblossom]

Belly fat can be visceral or adipose. I'm not an expert, but my understanding is that visceral is the one to worry more about. My guess is that that waist size approach works to the extent that maybe the more fat gained, the more visceral fat there is. I had my doctor evaluate my little tire and she said it's adipose and not as serious of a problem. I'd like to hear more about this difference.

Yes- with the visceral fat some people are TOFI, as mentioned here. (as opposed to adipose as you mentioned) The Dr Michael Mosley became this through eating a low fat diet for years, he was normal weight / waist though. I can't imagine any of us having this problem though as seems to be to do with excess sugar, processed carbs and too little exercise.

https://en.wikipedia.org/wiki/TOFI

https://www.sepalika.com/living-well/th ... side-tofi/

[Orangeblossom]

Also, the Framingham data showed that thin women with high adiponectin had higher rates of dementia. Adiponectin goes up when body fat goes down, so overweight females would have lower adiponectin. Adiponectin is a major rabit hole. One day I found all kinds of fascinating papers possibly relevant to us. Wanted to synthesize them but never got time and forgot all about it. Guess that's because I'm thin with high adiponectin.

I f you look at this page it seems to be quite complex. https://en.wikipedia.org/wiki/Adiponectin and this seemed to be the most recent research paper which seems to show a mixed picture. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5372608/. As you say, these things can be such rabbit holes

[Kenny4/4]

Also, the Framingham data showed that thin women with high adiponectin had higher rates of dementia. Adiponectin goes up when body fat goes down, so overweight females would have lower adiponectin. Adiponectin is a major rabit hole. One day I found all kinds of fascinating papers possibly relevant to us. Wanted to synthesize them but never got time and forgot all about it. Guess that's because I'm thin with high adiponectin.

I f you look at this page it seems to be quite complex. https://en.wikipedia.org/wiki/Adiponectin and this seemed to be the most recent research paper which seems to show a mixed picture. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5372608/. As you say, these things can be such rabbit holes

I know that I don’t know on this one.
There can be many confounding variables that aren’t adjusted for in the analysis. An example of this is smokers tend to be thin and skew results on studies related to weight that don’t adjust for them (most do). Diabetics tend to skew results to the negative as well.

The BMI studies are large and the effect of higher BMI being protective is consistent across the full range of weights.

That said I’m not going out to McDonalds today and ordering 2 chocolate shakes, a large Coke and 3 Big Macs because I read that a high BMI is correlated with a lower incedence of Alzheimer’s .

[circular]

That said I’m not going out to McDonalds today and ordering 2 chocolate shakes, a large Coke and 3 Big Macs because I read that a high BMI is correlated with a lower incedence of Alzheimer’s .

You mean I have to turn around? Was looking forward to meeting you there!

[Boireann]

I have never trusted BMI values. My BMI is 23.2 but my body fat % is 38. I have always had a very high body fat% even when young and thin. I am a 4/4 with no family history of AD but plenty of heart disease and stroke. So many factors to consider in this race to the finish line. Since going on a Keto 3/16 diet I have lost weight certainly but more importantly my sense of taste and smell has come back. And my memory is improving. That is most important to me right now! I never see much talk in medical journals and papers about body fat % outside of to say that it is the "gold standard" of body composition and disease... yet never actually documented in health studies on obesity.
~skinny, fat chick

[Kenny4/4]

My guess on this statistic of a higher BMI being correlated with a lower rate of Alzheimer’s is that it is a proxy for measuring the “cold” atrophic (type 2 in Dr. Bredesen’s book) form of Alzheimer’s.

Thin high adiponectin women would be the most effected because they would have the smallest sized brains and a naturally lower growth environment. A very large heavy and moderately healthy high Igf person would have a larger brain and would also be able to grow new synapses and neurons fast enough to keep up with the one’s lost to amyloid beta degradation.

That’s my guess on this stat.

[Julie G]

Since going on a Keto 3/16 diet I have lost weight certainly but more importantly my sense of taste and smell has come back. And my memory is improving. That is most important to me right now!

How wonderful, Boireann. Keep up the great work and please keep sharing your progress!

[Orangeblossom]

Study based in this, saying underweight not linked..

"Genetic and hence lifelong low BMI is not associated with increased risk of Alzheimer’s disease in the general population. These data suggest that low BMI is not a causal risk factor for Alzheimer’s disease and that the corresponding observational association likely is explained by reverse causation or confounding."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5505195/

[Orangeblossom]

Thought this was interesting-

"For postmenopausal women, estrogen levels increase with increasing BMI, presumably because conversion of androgens to estrogen in adipose tissue is a primary source of estrogen"

Wonder of higher hormonal levels in the postmenopausal women with the higher BMI might have something to do with it.

https://www.hindawi.com/journals/cmmm/2012/792375/

Higher BMI is also linked with later age at menopause -

https://www.ncbi.nlm.nih.gov/pubmed/12080450
"Among the variables studied, only BMI is related to age at menopause, and the greater the BMI, the later the age at menopause."

Underweight in women is also linked with an earlier menopause which in itself is linked with earlier cognitive decline https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3500688/

also
Relation of BMI and physical activity to sex hormones in postmenopausal women.

"Using a composite variable of BMI and physical activity dichotomized by median values, women with high BMI/low physical activity had a mean estrone concentration of 28.8 pg/mL, compared with 24.1, 19.9, and 18.4 pg/mL for women with high BMI/high physical activity, low BMI/low physical activity, and low BMI/high physical activity, respectively (p trend < 0.001). Similar trends were observed for estradiol and free estradiol"

Looks like being underweight is something to be avoided.- and may even interact with high activity levels on estrogen levels... (maybe not matter so much to those on HRT though- not sure!) Maybe better to be a normal weight and stay insulin sensitive, exercise etc rather than having low BMI as something to aim for? As Stavia mentioned in the primer weight to hip ratio is a better measure. than BMI anyway.

When you look at osteoporosis too, that is strongly linked in studies with a low BMI and is related to hormones as well. https://www.ncbi.nlm.nih.gov/pubmed/17125421

"...odds of bone loss decreased 12% for each unit increase in BMI (OR = 0.88, 95% CI 0.85-0.91).
CONCLUSIONS:
Women with low BMI are at increased risk of osteoporosis. The change in risk associated with a 1 unit change in BMI ( approximately 5-8 lb) is of greater magnitude than most other modifiable risk factors. To help reduce the risk of osteoporosis, patients should be advised to maintain a normal weight."

[Roamingseer]

Orangebloosom, I think this subject is a prime example of poorly designed studies.

1. The 2017 study you listed- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5505195/ points to non-casual. Further, it went back some 30+ years of patient data.
2. In other studies, how did they verify that their weight had remained nearly the same? Without referencing hard data, they may rely on spot readings to determine BMI.
3. As has been mentioned, those with higher BMI also have generally higher death rates from cancer and arteriosclerosis. Did the researchers account for this? Did they adjust for smokers being more prone to AD? Or, did they just look at people in their 70s, 80s, 90s with or w/o Alzheimer’s & use only this information?
4. What about international statistics?

I do wonder if lack of adequate fats can accelerate MCI & AD since it is robs the brain of essential fatty acids, which may trump insulin resistance over some span of years. In other words, eating a low fat diet for three decades could severely impact AD risk in one’s 70s or 80s, but an overweight person may not have significant insulin resistance until they’re in their 60s- allowing less time for brain damage.