The hazards of being obese

One of my favourite contrarian positions is that being overweight is not so bad. I don’t truly believe this but I like to use it to point out that although most everyone holds that being obese is not healthy, there is actually very little evidence to support this assertion. However, this recent rather impressive paper in the Lancet finally shows that being overweight or obese is really bad. The paper is a meta-analysis of hundreds of studies with a combined study size of over 10 million! The take home message is that the hazard ratio for dying is significantly greater than one but not too bad for overweight and mildly obese people (BMI < 30) but increases sharply after that. It is over two and rapidly increasing for BMI greater than 35. The hazard ratio gives the relative probability of mortality (or any outcome) per unit time (i.e. mortality rate) in a survival analysis, which in this case was a Cox proportional hazards model. The hazard ratio as a function of BMI is well fit by a quadratic function with a minimum around 22 kg/m^2. The chances of dying increase if you are thinner or fatter than this. The study was careful to not include smokers and anyone with a chronic disease and also did not start the analysis until 5 years after the measurement to avoid capturing people who are thin because they are already ill. They also broke the model down into various regions. Surprisingly, the chances of dying when you are obese is worse if you are in Europe or North America compared to Asia. Particularly surprising is the fact that the hazard ratio rises slowest in South Asia for increasing BMI. South Asians have been found to be more susceptible to insulin resistance and Type II diabetes with increased body fat but it seems that they die from it at lower rates. However, the error bars were also very large because the sample size was smaller so this may not hold up with more data. In any case, I can no longer use the lack of health consequences of obesity to rib my colleagues so I’ll have to find a new axe to grind.


5 thoughts on “The hazards of being obese

  1. I wonder if they have finally made a decision on whether a ‘calorie is a calorie’—eg a can of coke (with fructose) is the same as a can of orange juice. (I tend to think not but there are co-factors—orange juice may have some vitamin c etc in it;i only drink diet coke for the caffeine if I can’t make tea. soda with sugar in it is poison; ranks right up there with k-2 (also called bizarro, spice, etc.—really bad news but I guess some PhD chemists cant find jobs except doing knockoff/designer drugs. its right up my street and u get some very dangerous people as a result.)

    I just checked my BMI. wasn’t looking forward to it since I view myself as 10 or 20 lbs overweight. (some of this is since I drank about a gallon of water/tea/ and leftovers from last nite so it could be 5 lbs less). I still clock in at about 21—midway between underweight and overweight. (I have my own theory of BMI index).

    one thing I do agree on is excercize will not help you lose weight, except under certain conditions. i can lose 10 or more lbs in one day (due to ‘excercize’—basically hiking in mtns—-or swimming (in my case typically nearly drowning—I go swimming at times near great falls, and i hide but police somehow see me so they would send these helicopters and stuff after me so I ‘let go’ and head for the Chesapeake bay.i wasn’t drowning until they showed up===they should save somebody else. I would not recomend that–the water is deceptive. you better be able to hold your breath and deal with a whole lot of rocks.) I deal with some of these issues of keeping weight off (and also avoiding other bad habits) by not keeping anything in my place, or very little—if I want to eat I have to go get it in the ‘pantry’ (its about a mile or 2 in the park at nite) and I used to keep my beer and cagarettes up on the mountaintop (about 2 miles and about 1600 feet uphill–I could do it in 1 hour). drink a beer , watch the sun go down, and then follow the bobcat trail back home—downhill was only 45 minutes (unless ypu fell off a cliff in the snow–add 15 minutes for that).

    I wonder if aging is a risk factor in mortality. one could also have stuff like ‘ageism’. this may be more of a social thing.
    ‘error bars’ I’ve heard of. maybe this is like when you serve 30 years in jail for a crime you didn’t commit.

    i’m amazed—I can buy good spinach salads now for same price as french fries. its catching on too—people who only used to eat junk food now buy salads and fruit. and while it may not be the cheapest since you can make your own its convenient if u don’t have time.


  2. cc—I basically agree with that post which I had seen. I am really thinking about ‘externalities’ —a calorie may be a calorie but context is also an issue. (I think this is why that study or tv show which had people lose alot of weight quickly showed they didn’t keep it off in general, and also their ‘set point’ or something had changed so when they went to a ‘normal calorie diet’ at their lower weight which presumably would keep it constant, they actually still gained weight. so, they had to eat fewer calories than before to stay constant. (I think this is also why indigenous people like bolivian indians who chew coca leaves all day don’t have the same reactionms as people who use the processed forms used in usa).

    I know if I buy a bag of potato chips and eat it all at once, this is worse than spreading it through the day even tho the calories are the same—its an overdose at one time . (maybe this is a form of ‘simpson’s paradox’ or ‘group selection’ in biology, or Milton’s friedman’s ‘a dollar is not a dollar not a dollar’ —a form of noncommutativity. if you eat breakfast before , say, school, that may differ from eating it after school, because humans are not conservative systems. (I don’t remember what the consensus is on whether the universe as a whole is—‘black hole information paradox’ etc.)


  3. @ishi when you say you know does that mean there is an adequately powered randomized controlled study that shows this or just that you feel this way?


  4. when I say ‘i know’ that meant ‘ i just feel that way’—anecdotal report. I do wonder about ‘rate’ affects. this goes back to the original issue—-one view was that ‘natural sugars’ even though caloric-wise having the same energy as artificially processed ones (frustose) are metabolized differently, and because of these differences lead to metabolic differences in people.

    They basically get ‘rewired’ so even if 2 people have same BMI or weight if they are ‘wired differently’ and 1 eats sugar via sugar cane (natural) vs fructose they will experience different changes in weight. I have heard some people (maybe athletes) use energy in different ways (though I don’t know iif that’s theoretically possible) so for them a calorie is not a calorie—some get more bang for the buck, or have changed their baseline metabolic rates. People could begin with identical BMIs , weights, and diets and be confined to the same physical environment and activity and evolve to different weights/bmi’s. (This would be because for example some may increase their heart rates or run a fever endogenously rather than do different physical activity.) . . This is likely something I can look up.

    (I do know I once had sepsis, and was continually pressured to eat almost twice as much as I usually do, and was confined to a bed, but still lost 15 or 20 lbs over 6 weeks. I was also almost angry about the fact that they watched my diet since I figured i’d be 300 lbs in no time but it didn’t happen—went opposite way. I was thinking after that of starting a weight loss clinic which advertizes ‘you can lose 20 lbs in a month while still eating all you want—cake, cookies, burgers, peanut butter sandwiches’. . . thats the only time I ate meat in last 20 years except a couple times at relatives–I figured go back in time and have one last cheeseburger for the road. eventually they told me I had to get out but i i showed them i could walk by myself (barely) —my physical therapists refused to deal with me (they said I was too sick) so I got a nurse (from Jamaica) to help me. I looked like a concentration camp survivor when I got out.

    ‘rate ‘ is where it is at. food or calories may be like drugs—taking 20 pills in one hour and waiting 20 hours for the next dose,may not be the same as taking 20 using 1/hr in 20 hours


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