Home » g Factor » Obesity and Intelligence

Obesity and Intelligence

Enter your email address to follow this blog and receive notifications of new posts by email.

Join 292 other subscribers

Follow me on Twitter


1600 words

[Edit: My view here has changed, read my recent article Is Diet an IQ Test?  It isn’t and it is, of course, much more nuanced than ‘IQ’ (which is a proxy for social class’ leading to obesity which would imply lack of funds and education on what and when to eat. Obesity is much more complex than ‘IQ’, numerous other variables come into play and since ‘IQ’ (which is just a proxy for general knowledge ‘is low then the individual in question won’t know what and when to eat and since this occurs in low income families more often than not who have low IQs then this effects them the most.] 

The relationship between intelligence and obesity is often misinterpreted. Numerous studies have concluded that becoming obese leads to a drop in IQ. This mistake happens due to improper interpretation of cross-sectional studies. However, analyses of population-based, longitudinal data show that low intelligence from birth causes obesity. No credible evidence exists for obesity lowering intelligence. There are, however, mountains of evidence showing that low intelligence from childhood leads to obesity (Kanazawa, 2014).

Kanazawa (2014), reviewed the data on the research between obesity and IQ. What he found was that those studies that concluded that obesity causes lowered intelligence only observed cross-sectional studies. Longitudinal studies that looked into the link between obesity and intelligence found that those who had low IQs since childhood then became obese later in life and that obesity does not lead to low IQ. Those with IQs below 74 gained 5.19 BMI points, whereas those with IQs over above 126 gained 3.73 BMI points in 22 years, which is a statistically significant difference. Also noted, was that those at age 7 who had IQs above 125 had a 13.5 percent chance of being obese at age 51, whereas those with IQs below 74 at age 7 had a 31.9 percent chance of being obese. This data makes it clear: low IQ is correlated with obesity, so we, therefore, need to find sufficient measures to help those with lower IQs to learn how to manage their weight.  Moreover, the lack of ability to delay gratification is also correlated with low IQ (Mischel, Ebbeson, and Zeiss, 1972).

Less intelligent individuals are more likely to become obese than those who are more intelligent. With what we know about low IQ people and how there is a strong relationship between low intelligence and lack of ability to delay gratification, we can see how this lack of thought for future problems for their actions in the present can manifest itself in obesity.

This study claims that there is a link between morbid obesity and a drop in IQ. The researchers compared 24 children who weighed 150 percent of their bodyweight before age 4 with 19 children and adults with Prader Willi’s Syndrome, using 24 siblings as controls as “they share the same socioeconomic environment and genetics”. Prader Willi’s Syndrome (PWS) is a chromosomal disorder in which chromosome 15 is deleted. They have an almost insatiable desire to eat,which can cause one suffering from PWS to eat themselves to death. Those with PWS were found to have an IQ of 63, while those who became obese were found to have an IQ of 78 with the control siblings having an IQ of 106. The researchers were surprised to see such a difference in IQ between siblings. They then state that this could be one facet of obesity that could be irreversible. MRI scans of the cohort discovered white matter lesions on the subjects with PWS and early-onset obesity. The researcher says that these lesions could affect food seeking centers in the brain leading to a want to gorge on food. Seeing how those with PWS eat when unsupervised, this is an interesting hypothesis.

This study compared 49 teens with metabolic syndrome and 62 peers without the disorder, while controlling for socioeconomics status. They found significantly lower scores in arithmetic, attention and attention span, spelling, mental flexibility and regions of the brain with lower volumes of matter in the hippocampus and white matter integrity.

There are a few problems with these two studies. In a population-representative birth cohort study of 1037 children, it was found that cohort members who became obese had a low IQ, as expected. But, contrary to what your study said, cohort members didn’t exhibit a decline in IQ from becoming obese, they instead had a lower IQ since childhood. There is no evidence of obesity contributing to a decline in IQ, even in obese individuals and those on the verge of metabolic syndrome. Another problem is that they wrongly conclude that obesity leads to lowered intelligence, completely misinterpreting the extremely strong negative correlation between obesity and intelligence.

This study shows how obese mothers give birth to less intelligent children. In an observational study (already garbage), the researchers took 3412 participants and found a strong relationship with pre-pregnancy obesity and math and reading scores in children. For math, a 3 percent reduction was observed. There was a 3-point drop in reading scores with math scores showing a decline of 2 points. These differences are within the normal variation between tests, so it’s nothing to take note of. Also, this is an observational study. I have shown above that longitudinal studies are superior for this, as well as researchers misinterpreting the results found from their studies.

There is a strong relationship between parental years of education and childhood obesity. Since the mother’s IQ is the most important predictor of a child’s IQ *, that passes on to the child as well. (BMI is also 80 percent heritable). **.

So because of those factors involving the mother and child, that is what accounts for it. Not the environmental factors brought up.

This study claims that overweight parents are more likely to fail. This is all due to the fact that low IQ people are more likely to be obese or overweight, with heritability of BMI being .8, you can see how low IQ is the cause of both of those variables. 

This shows that binge eating is linked to memory loss. I heard about a study a few months ago actually like this. Rats were fed high fat diets and they noticed that the brain microglia actually started to eat neuronal pathways actually leading to a decrease in cognitive ability. But they said that returning to a new diet will stop its effects. Researchers say the negative cognitive effects are reversible, but I already gave the citstion about obesity not being linked to decreased IQ. I should also note that this study was carried out on rats and while this may be a factor for humans as well, a few studies need to be done.

Binge eating, however, actually has a genetic component. Though this was only observed in girls. One reason I can think of for this is that women need higher body fat for a leptin release so puberty can begin so they can bear children.

This article purports to show 5 ways obesity affects the brain. Obesity does cause food addiction, however, those who lack the ability to delay gratification are more likely to not be able to control their impulse to overeat. I always link to the MRI scan showing the control, obese and cocaine user’s brain. Interesting to see that sugar is just as addictive as cocaine. Obesity doesn’t make us more impulsive. Check out the Marshmallow Experiment, as well as its follow-up studies. Those who are more impulsive are more likely to be obese, as well as have lower SAT scores.

Satoshi Kanazawa also noted that childhood IQ predicted whether or not one would become obese at the age of 51. General intelligence in childhood has a direct effect on weight gain, BMI, and obesity, net of parents education and SES, parents BMI, the child’s social class, and sex. More intelligent children grew up to make healthier choices, and therefore stayed leaner than those children who were less bright. The link between childhood obesity and intelligence also shows that the effect between childhood is unmediated by education of income. Meaning, those with lower IQs in a higher socioeconomic bracket STILL have the same chance of becoming obese as those in the lower socioeconomic bracket. Finally, parental BMI itself is a consequence of parental general intelligence, which the parents pass on to their children. This shows the extremely high heritability of obesity as well as showing how intelligence plays a factor in the causes of obesity.

The known differences in ethnic obesity rates generally mirror the intelligence of those populations. All populations are showing a sharp dysgenic decline, which coincides with a more obese population as well. Sociologists and the like may say that those who are poor cannot afford the same types of food that those who have more wealth can. However, this is a false statement. Whole foods are not more expensive. The conclusion that was (obviously) reached is that there is expensive and non-expensive junk food as well as whole foods. Natural diets will not cost more, all things being equal. If you know how to eat and how to buy food, you will avoid spending too much money. This goes back to intelligence. One with a higher IQ will be able to think of what his present actions will lead to in the future while those with a lower IQ live in the now without a care for the future, which then manifests itself in their obesity.

There are numerous articles showing that the causality for low intelligence is not becoming obese, but that those who become obese have a lower IQ since childhood. Longitudinal studies show the relationship, while observational studies show that obesity drops intelligence. Clearly, observational studies are inferior for seeing the relationship between IQ and obesity. This then leads to researchers misinterpreting the data and drawing wrong conclusions.

The IQ of the mother is the most important factor in determining the future intelligence of the child.

** This is a great one. In a meta-analysis of twin and family studies, including mono and dizygotic twin studies, with a sample of 140,525 people, heritability of BMI was found to be between .75 and .82. Both extremely high correlations. Since the heritability of intelligence as well as height (another good predictor of intelligence), there is good evidence for the claim that becoming obese is due to lower childhood IQ, which is genetic in nature.



  1. mobiuswolf says:

    I’m surprised anyone thought otherwise, but I see from a quick search “fat and stupid” it’s the pprevalent opinion.


    • RaceRealist says:

      People get one thought in their head and run with it, despite evidence to the contrary. A lot of factors in life have to do with intelligence, despite people’s aversion to the truth.

      This shows that we need to think of better measures to help the obese, maybe better nutrition education for those who are less intelligent. Nutrition really does need to be taught in school more, this would mediate some of these problems we have with the obesity epidemic at present.

      Liked by 1 person

    • mobiuswolf says:

      I seriously doubt education would help. It’s a moot point anyway, with the establishment pushing all the crap fake food.


    • RaceRealist says:

      Well, education would help if the right things were being taught.

      I remember my health classes in high school; I didn’t learn a thing about nutrition. Everything I know I’ve taught myself. But that’s because I personally have the drive to want to be knowledgeable in regards to diet.

      Even then, as you say, that it’s the establishment pushing food on us, you’re 100 percent right. The media has a huge say in what people eat:

      Obesity has become a worldwide public health problem. Considerable research has shown that the media contribute to the development of child and adolescent obesity, although the exact mechanism remains unclear. Screen time may displace more active pursuits, advertising of junk food and fast food increases children’s requests for those particular foods and products, snacking increases while watching TV or movies, and late-night screen time may interfere with getting adequate amounts of sleep, which is a known risk factor for obesity. Sufficient evidence exists to warrant a ban on junk-food or fast-food advertising in children’s TV programming. Pediatricians need to ask 2 questions about media use at every well-child or well-adolescent visit: (1) How much screen time is being spent per day? and (2) Is there a TV set or Internet connection in the child’s bedroom?

      Children, Adolescents, Obesity, and the Media

      Banning junk food advertisements on television as well as getting kids up from the TV and going outside to play will increase physical activity, leading to more lean muscle mass, and at the same time getting rid of the poison known as the MSM and its advertisement propaganda to children.

      The corporations have too much to lose by pushing healthy food, if no one ate their garbage they would go under. They want people to be complacent and not think about a proper diet, because they acquire more money in the process.

      This goes back to how sugar affects the brain and is as addicting as cocaine. Over 80 percent of the food on our shelves has added, unneeded sugars.

      By getting rid of the unneeded sugars in our food along with getting rid of junk food propaganda on television, that would be a great start.

      I remember a few years ago the NYC mayor put a ban on large soft drinks. I agreed with it fully. But, of course, people had to complain. You sure need that 128 oz Super Big Gulp from 711!!

      This is part of the reason why we are becoming such an obese society. Instant gratification NOW.

      Liked by 1 person

    • mobiuswolf says:

      Just so. Public school is a wasteland, a part of the media, all aimed at creating docile little rabbits. Health , good or ill, is irrelevant to their purpose.

      I haven’t even seen a commercial in at least 15 years. We get netflix, but there is little of interest there. The grand-kids (home-schooled) get to watch carefully screened shows and dvds, though if were up to me they’d get to watch less.

      The last several years we have switched to a more or less paleo diet and you know, my hair has started growing again. It hadn’t grown an inch since the army cut it off 40 years ago. I can actually tie it back now.

      People only learn if they are self-motivated. That’s a very few. Repetition (school, msm) can brainwash them, but they only parrot. They still know nothing. I’m sure you have tried reasoning with them. Futile.
      I’m afraid the rabbit apocalypse is inevitable. The sooner the better, I say. I hope you’re in a good spot to weather it.

      Oh yeah, rather than try to regulate people’s behavior, I’d like to see them require labeling for all the poisons they put in everything, similar to the warnings on cigarettes, only complete.


    • RaceRealist says:

      Paleo. I have a few posts on that. Mainly talking about the supposed magic benefits of it, which aren’t backed by science. But if it you stay on point it’s fine. People who do paleo for the “magic benefits” are fooling themselves.

      That’s good your grandkids hardly watch TV. That’s part of how we have to combat what the corporations are putting through to children.

      Your hair problem probably had to do with a shitty diet as a whole and eating whole foods had your hair grow at in a normal matter.

      Motivation, whether to exercise or what else, had a genetic component. Just as delay of gratification is partly due to genetic factors. This is why we need to, in my opinion, curb the garbage commercials that push trash food on people who don’t know any better nor who don’t have a good idea on how to eat healthy.

      I forget where this happened, but putting kcal counts on restaurant items has people curb their kcal intake considerably when out to eat. That’s one way to get it done.

      Liked by 1 person

    • mobiuswolf says:

      I don’t really know if it’s paleo or not, just real food. Meat, vegetables, fruit, all carefully sourced or home grown, Pretty much my preferred diet anyway, but I used to eat a lot of whatever, as well. I burn a lot of cals. We did cut the gluten, which seems to have helped with the joint problems. I miss bread though. :o)

      We quit eating out, too. It was usually a disappointment and you really don’t know what you’re getting. Trust is a thing of the past.

      Time to go test drive the 1911. Keep up the good work. :o)


    • RaceRealist says:

      Don’t worry about gluten. In this study, it was found that each treatment diet, whether it contained gluten or not, prompted subjects to report a worsening of gastrointestinal symptoms to similar degrees. Even when the placebo diet was identical to the baseline diet, the people still reported a worsening of symptoms. They could find absolutely no specific response to gluten.

      It doesn’t exist.

      But yea going from a diet with hardly any nutrients to a diet with a good amount of nutrients will have effects like that.

      I eat out sparingly. Though I know how to manage my kcal intake.


    • mobiuswolf says:

      I believe the gluten free aspect was adopted because our oldest boy has lymes. I miss the home made bread but not the pasta gas.


    • RaceRealist says:

      Don’t believe it. It’s just one of the many ‘fad diets’ like paleo, in which people think it have magic benefits for them. In this case, non-celiac gluten sensitivity.

      In a placebo-controlled, cross-over rechallenge study, we found no evidence of specific or dose-dependent effects of gluten in patients with NCGS placed diets low in FODMAPs.

      No effects of gluten in patients with self-reported non-celiac gluten sensitivity after dietary reduction of fermentable, poorly absorbed, short-chain carbohydrates.

      Just another ploy to get the average nutritionally retarded American to believe they have this ‘disease’ when placebo-controlled studies show otherwise.

      Liked by 1 person

    • Leo Gant says:

      I know i know, I’m a year and a month late but here’s my opinion. I’m fat and I have an IQ of 120 but I also suffer from depression so that could play a factor in my pudgy life style.

      Liked by 1 person

    • John Connor says:

      Leo Grant – In that case, you’re clearly an outlier.


  2. Marcus Brutus says:

    I’m fat and smarter than anybody on this board.


    • RaceRealist says:

      What are…. averages?

      The correlation between obesity and intelligence is .25.

      Though, those who had their IQs measured at age 3 and had lower IQs were more likely to be obese in their 50s.

      One single data point does not disprove averages.


    • Santoculto says:

      ”The correlation between obesity and intelligence is .25.”

      0,25% is not a lower correlation.

      what exactly it mean*

      0,25% is the same than 25%**

      than 25% of a sample of ”smarter” people are obese… and in USA**


    • RaceRealist says:

      Excuse me Santo, the correlation is -.25. Meaning as one variable goes up (weight) the other goes down (IQ). Not to say that as you gain weight you lose intelligence, but your IQ at childhood dictates your weight at adulthood.


    • Santoculto says:

      you don’t answer my questions…


      well, i don’t think

      ”your IQ at childhood dictates your weight at adulthood”

      It’s not causal


  3. Leo Gant says:

    I have been fathletic my whole life. I’m considered obese but I also hold an IQ of 120 would’ve been higher but I was plastered when I took the test. The point is IQ is only tied to the levels of potential stupidity. Either you’re gonna be the motherfucker with the ideas or you’re gonna be the motherfucker doing the work.


  4. jennifer grinder says:

    This is really interesting research. I’m curious about the fact that average IQ has risen (potentially as much as 30 points) over the last 100 years. Assuming that research is sound, and there is a LOT of research, why are obesity rates rising contemporaneously?


    • RaceRealist says:

      Assuming that research is sound, and there is a LOT of research, why are obesity rates rising contemporaneously?

      I can talk about this for days and days (literally) and I will write an article on it eventually (because it’s too much to put into a comment), but you only need to look at diet quality. In the 60s fat was demonized since it ’caused heart disease’ (it doesn’t; “A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD.“; Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease) and so to fill out the remaining kcal that was lost from lowering fat, carbs were upped.

      Now we need to know about what carbs do to us. Processed carbohydrate consumption spikes insulin levels. Spiked insulin levels cause blood glucose levels to rise which then lowers insulin. Continuously spiking blood glucose with processed carbs, along with chewing on something at all hours of the day causes insulin levels to stay elevated. So therefore, a vicious cycle begins where insulin is spiked due to glucose being spiked and it becomes a self-reinforcing cycle.

      Obesogenic environments are also another cause (which I have written about as well). We have paleolithic genomes in modern, obesogenic environments. Change the environment, change the country’s weight.


  5. Jennifer Grinder says:

    Race Realist, I definitely look forward to reading your article.
    Obviously environment has a lot to do with the rise in obesity, but how does one explain that the longitudinal studies have found that children who have low IQ (who are not overweight) are predicted to be obese at age 51 when they are tested again? (The studies are adjusted to control for SES, race (this is in European test subjects) and family history of obesity).
    The studies could not find evidence for obesity causing a decrease in IQ, but low initial IQ determining future obesity risk. I’ll have to look up the percentages but it was astounding.
    Thanks, Jennifer


  6. Jennifer Grinder says:

    Also-are you thinking this is epigenetic?


  7. Samantha says:

    It’s really not surprising….if you’re supposedly having severe financial difficulties the logical thing to do would be portion/ration out whatever food you can acquire and make it last a few average or smaller meals instead of binge eating 3-4 meals in one sitting….then having to buy more…and subsequently not have enough for rent…..


    • RaceRealist says:

      Processed foods are cheaper. High sugar intake changes the brain to look like that of a drug addict. There are numerous reasons why the poor are fat, but ‘IQ’ isn’t a direct cause, but it is indirectly because it reflects social class which is why ‘IQ’ shows high correlations with things such as diet, brain size, and life expectancy.

      Either way people, and this goes for anyone no matter the race, are ignorant to nutrition and if they were told a bit of truth then outcomes would be different than they are now.


Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

Please keep comments on topic.

Blog Stats

  • 874,603 hits
Follow NotPoliticallyCorrect on

suggestions, praises, criticisms

If you have any suggestions for future posts, criticisms or praises for me, email me at


%d bloggers like this: