The idea that a high BMI appears to be protective and decreases death in people, but also is associated with increased risk of death.
***More simply put - there is data out there that shows being overweight can be a good thing for some, yet a bad thing for others***
HTN : hypertension
Normal BMI (Nml) <25
Overweight (OW) BMI 25-29.9
Obese (Ob) >= 30
Evidence showing OW+ is bad for our health:
Tons of it out there, I don't think I need to list too many. But here are some as it is still important to remember this.
Arch Intern Med. 2002 Sep 9;162(16):1867-72. Overweight and obesity as determinants of cardiovascular risk: the Framingham experience.Wilson PW1, D'Agostino RB, Sullivan L, Parise H, Kannel WB.
Looked at relationships between BMI and CVD risk factors, CVD endpoints prospectively from the Framingham HEart Study of ppl 35-75 who were followed for up to 44 years.
CV endpoints the looked at: Angina, MI, Coronary hrt dz, or stroke.
Conclusions: the overweight category is assoc with increased relative and population risk for HTN, and CVD.
Ob risk of HTN was 42%
OW risk of HTN was 27.8%
Nml risk of HTN 15.3%
NHANES III (1988-1994) to NHANES III (1999-2000)
Showed increase prevalence of Metabolic Syndrome (MetSyn) and that weight was associated with increased risk of MetSyn:
N Engl J Med. 2002 Aug 1;347(5):305-13.Obesity and the risk of heart failure.Kenchaiah S1, Evans JC, Levy D, Wilson PW, Benjamin EJ, Larson MG, Kannel WB, Vasan RS.
5881 participants in Framingham. Used Cox proportional-hazards model
Found: For each 1 unit increase in BMI women’s risk of heart failure increased by 7%, 5% in men.
Nurses’ Health Study
114,281 female registered nurses aged 30 to 55 years who did not have diagnosed diabetes mellitus, coronary heart disease, stroke, or cancer in 1976. Over 11 states.
BMI <22 assoc with lowest risk of T2DM
BMI >35 was associated with 6X higher “relative risk” of T2DM
Look AHEAD study and others
Have shown that even a 5% weight loss can improve risk profiles for diabetes and cardiovascular health
Lancet. 2014 Aug 30;384(9945):755-65. doi: 10.1016/S0140-6736(14)60892-8. Epub 2014 Aug 13.Body-mass index and risk of 22 specific cancers: a population-based cohort study of 5·24 million UK adults.Bhaskaran K1, et. al.
“Assuming causality, 41% of uterine and 10% or more of gallbladder, kidney, liver, and colon cancers could be attributable to excess weight. We estimated that a 1 kg/m(2) population-wide increase in BMI would result in 3790 additional annual UK patients developing one of the ten cancers positively associated with BMI.”
***granted i’m not sure any paper should have been published that uses the world “assume.” After all that just makes a “bleep” out of you and me. But as other studies do seem to show an assoc we’ll let it slide***
So there is a lot of data out there that shows associations between excess fat mass and MetSyn, HR, cancers, and 200+ diseases. From some evidence you would conclude that obesity does cause health problems.
The Obesity Paradox:
The strange thing is of the people getting diseases, the people who have the better prognosis are the ones overweight!!! And while all the above more talk about risk factors, we still do see patients of normal weight getting HTN, having coronary hrt disease, T2DM, getting the other 200+ diseases.
Am J Med. 2007 Oct;120(10):863-70.Obesity paradox in patients with hypertension and coronary artery disease.Uretsky S1, et. al.
22,576 ppl with HTN and CAD
Outcomes looked at: first occurrence of death, nonfatal myocardial infarction, or nonfatal stroke.
Obese Class I(30-35) had a HR of 0.68 compared to Nml BMI patients.
Lancet. 2006 Aug 19;368(9536):666-78. Association of bodyweight with total mortality and with cardiovascular events in coronary artery disease: a systematic review of cohort studies.Romero-Corral A, et al.
Method: selected cohort studies that provided risk estimates for total mortality, with or without cardiovascular events, on the basis of bodyweight or obesity measures in patients with CAD, and with at least 6 months' follow-up.
Found: found 40 studies with 250,152 patients that had a mean follow-up of 3.8 years.
Patients with(BMI) (ie, <20) had an increased relative risk (RR) for total mortality (RR=1.37 [95% CI 1.32-1.43), and cardiovascular mortality (1.45 [1.16-1.81]),
overweight (BMI 25-29.9) had the lowest risk for total mortality (0.87 [0.81-0.94]) and cardiovascular mortality (0.88 [0.75-1.02]) compared with those for people with a normal BMI. Obese patients (BMI 30-35) had no increased risk for total mortality (0.93 [0.85-1.03]) or cardiovascular mortality (0.97 [0.82-1.15]). Patients with severe obesity (> or =35) did not have increased total mortality (1.10 [0.87-1.41]) but they had the highest risk for cardiovascular mortality (1.88 [1.05-3.34]).
Am Heart J. 2008 Jul;156(1):13-22. doi: 10.1016/j.ahj.2008.02.014. Body mass index and mortality in heart failure: a meta-analysis. Oreopoulos A1
METHODS: searched the Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, Scopus, and Web of Science to identify studies with contemporaneous control groups (cohort, case-control, or randomized controlled trials) that examined the effect of obesity on all-cause and cardiovascular mortality.
RESULTS: Nine observational studies met final inclusion criteria (total n = 28,209). Mean length of follow-up was 2.7 years.
both overweight, RR 0.84, 95% CI 0.79-0.90) and obesity, RR 0.67, 95% CI 0.62-0.73) were associated with lower all-cause mortality in pts with CHF
Logue J, Walker JJ, Leese G et al (2013) The association between BMI measured within a year after diagnosis of type 2 diabetes and mortality. Diabetes Care 36: 887–93
Study of 106 640 participants in Scotland.
The lowest risk of mortality was in those diagnosed with type 2 diabetes and a BMI of around 30 kg/m2 , and those with a BMI between 20 and 25 kg/m2 at time of diagnosis had a 20–30% increased risk of death during the follow-up period.
Obesity Paradox in End-Stage Kidney Disease Patients. Prog Cardiovasc Dis. Author manuscript; available in PMC 2016 Jan 31. Jongha Park, MD, et al.
Mortality as outcome
Class 1 Ob had the best relative risk of .73, BMI <20 had the worst risk.
Explain Yourself Than Lucy
There are the easy explanations that seemingly do factor in for many of the above results…
- Studies looking to discover risk factors study risks of Nml to Ob, vs Obesity paradox studies are more comparing Obese to Nml. More minor, but could play a role.
- Obviously BMIs of 20 in a patient with a disease increase mortality from a cachexia stand point.
- The disease itself has caused the lower weight. (Reverse Causality study flaw)
- Ppl at Nml BMI could be “more sick” or have a more aggressive form of the disease.
- Maybe symptoms are more prominent in the Ob (shortness of breath, increased pain) and thus seek more medical care.
- Maybe even the obese are targeted earlier by the medical community for earlier prevention, or have more stringent risk management modifiers.
- Maybe Nml BMI people are overlooked because it is taken for granted they are “healthier” and thus at less risk.
BUT...There could be a more complex factors affecting some of the population. I mean come one we are physicians, we don’t settle with easy 😉
- The idea that exposure to some "harm" is protective. We see this in other places...nature animals being exposure to low dose of some food that are poison actually cause the animal to turn on some gene expression that help them in other ways. (I am completely blanking on this term today for some reason, someone please help me out!). Even to if low doses of UV exposure is healthier, and maybe some people shouldn't be wearing as much sunscreen?!? [please don't come after me dermatologists 😉 ]
- No fat is created equal:
Subcutaneous fat in the thighs
SubC fat in abdomen
“Dysfunctional fat” basically it is what happens if the adiposites do not develop healthfully... with adequate blood flow sources, abundant mitochondria, and or supportive structures. If they start to lack in any of these factors, especially when they hypertrophy, hypoxia occurs, the fat cells die and cause inflammation ---> lots of downstream bad things.
Fat cells that developed in the thighs for example have the least amount of propensity to become “dysfunctional," vs fat around the heart and liver tend to be the worst. And even relatively small amounts of dysfunction fat can be more detrimental, compared to larger volumes in the thighs, for example.
This could explain why a “thin” patient with a small “belly pouch” could have a worse outcome could when compared the the guy next door but with more a pannus(subcutaneous abdominal fat). Especially after some hypotensive event where the fat cells are now exposed to a low oxygen environment they otherwise would not have been exposed to.
3. The Metabolically healthy obese person -
These people are thought to have a higher capacity to store fat that is less “metabolically active,” to have "benign" fat essentially.
Side note: one might be able to improve our genetic expression of factors to help promote good fat….exercise!
“A metabolically healthy obese phenotype can be promoted by exercise, but is also linked with intrinsic AT(adipose tissue) molecular characteristics such as efficient fat storage and lipid droplet formation, high adipogenesis capacity, low extracellular matrix fibrosis, angiogenesis potential, adipocyte browning and low macrophages infiltration/activation. Such features are associated with a secretomic profile of human AT which is protective for the cardiovascular system. In the present review, we summarize the existing knowledge on the molecular mechanisms underlying the 'obesity paradox' and whether fatness can be healthy too.”
study link: https://www.ncbi.nlm.nih.gov/pubmed/28549096
So what to do with all this??
After all, we still pretty much know a Nml BMI is associated with decreased risk of pretty much all cause morbidity and mortality compared to a high BMI, and not only that we do see health benefits in decreasing abnormally high BMIs.
Basically I see this information as being helpful in two basic ways:
Stop thinking about weight loss in terms of body image. It is easy to get lost in how we "should" look based on cultural pressure. But how many times have culture pressures been wrong?...many, many times through history have people gotten things wrong...like lots.
And thus a good reminder weight loss is not all about the scale. Each person is different.
And also for my own personal admin of WPWI, with recent posts...there is no way for me to screen everyone, know everyone, know their medical and family hx. All we know is pretty much what you have let us know about you through your posts and pictures. That is it.
For my first official Friday Informational 😉 I didn’t want it to seem like I am “picking” on normal weight ppl by posting information of why we do not support weight loss in people with nml BMIs. So to prove I am not out to “pick” on anyone, which I have been accused of, I thought I would start with an actual presentation that even in some overweight/obese people weight loss might not actually be the key to improving outcomes! Probably not all OW/Ob people, but in some people...like that female who does not smoke with HTN, BMI 27, maybe she is wasting her time and mental happiness always worrying about weight. Maybe she should more be taking the time making sure she knows about more just eating healthy, and exercise. Exercise not to lose weight, but more to decrease CV risks, but also now to continue to, or continue to have her body promote fat mass being stored in thighs, vs in visceral tissue.
Next week, yes we will be talking more, presenting evidence about why WPWI is a support group of those with a history of having elevated BMI to lose weight for potential health benefits. #headsup
***As always please being kind and forgiving of grammatical errors,a physician women only has so much time in her day. #editingstinks ***