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More than a third of adults in the U.S. are obese. And many of those already overweight continue to put on even more pounds. Now researchers have a clue why.
Two new studies in the Journal of Clinical Investigation suggest how obesity and high-fat diets might actually alter the way the brain works, changing in particular the hypothalamus. This almond-sized area of the brain helps regulate hunger and thirst, as well as sleep and body temperature. So if it’s out of whack, people can feel hungry even when they've consumed plenty.
One study found that in the brains of both obese humans and obese rats, neurons around the hypothalamus were damaged by inflammation. High-fat diets have been known to promote inflammation throughout the body, but that usually takes weeks or months to appear. Changes in the brain, however, can happen fast—even within 24 hours. [Joshua Thaler et al, Obesity is associated with hypothalamus injury in rodents and humans]
The second study found that mice on a fatty diet were slow to replace old neurons in the hypothalamus, which could also hamper its function. [David McNay et al., "Remodeling of the arcuate nucleus energy-balance circuit is inhibited in obese mice"]
So you might consider starting 2012 by watching the ball drop—and dropping the cheese ball.
—Katherine Harmon
[The above text is a transcript of this podcast.]
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16 Comments
Add CommentI want to see the details of this study. Most high fat diets used in these studies are also high in carbohydrates. If the diet was ketogenic then the details of this article would surprise me. Until then drop the rice cakes, bread, pasta, oatmeal, all carbohydrates except fibrous veggies. We all know complex carbohydrates lead to diabetes and obesity. Where are those studies? Where are the studies on ketogenic diets? If you are going to quotes studies provide more information because it is unethical to quote studies without giving us the true nature of the study. Carbohydrates are not an essential nutrient and the culprit in the obesity epidemic.
Reply | Report Abuse | Link to thisCarbohydrates are the culprit in the obesity epidemic. Just search the internet and read what insulin does. Insulin's main goal is not to lower blood sugar, insulin's objective is to store excess nutrients. Our body only has one hormone for lowering blood sugar and it is not even the main objective of that hormone. That should tell you something. Fat does not stimulate insulin and with low insulin you burn fat and when you lower fat you lower leptin levels and insulin levels even more. You eat sugar you burn sugar and store fat by raising insulin. Fat is only burned when insulin is low.
Reply | Report Abuse | Link to thisGood advice to drop the cheeseballs! Say, 'cheese', don't eat it is the anti- dementia diet.
Reply | Report Abuse | Link to thisWe used to be a cheese addicts ( due to its salt content, triggering an automatically 'moreish' salt-lick reflex,
as I now know), and went on a de-salination diet, gradually decreasing the cheesy bits.
It worked! Our taste buds are very hi fi quality now.
Regarding the other health risk in cheese: concreted & fermented bovine lactic excretions, with growth hormones, DDT remnants etc. all fat-soluble & preserved in the fatty condensate: It's best to avoid. Our food was never meant to be greasy, or cheesy-
let's consider our evolutionary origins...
Any fat concentration must, on a nano scale as well, block vital pathways of inter-cellular & neural communication;
a nano-oil slick is still a disaster zone, especially in our 'brainiest' center: the grey matrix.
Youthevity.com
I am sure of not getting troubled by fatness.If brain starts skrewing up in hypothalamus then i should think of getting operated on my stomach so as to reduce intestines length to get slim.
Reply | Report Abuse | Link to thisLimit protein eliminate sugar and consume fat and you will burn fat.
Reply | Report Abuse | Link to thisThe brain is made from fat. If you only consume carbohydrates you are headed towards dementia faster than you can say cheese! We evolve to eat fat. Without fat you cannot survive a famine. The stores of sugar are gone in a day. Fat can last weeks. The brain is made from omega 3. Cheese is bad though, you are right about that. We did not evolve eating dairy.
Reply | Report Abuse | Link to thisYou commented, "Until then drop the rice cakes, bread, pasta, oatmeal, all carbohydrates except fibrous veggies. We all know complex carbohydrates lead to diabetes and obesity."
Reply | Report Abuse | Link to thisDidn't you mean "simple carbohydrates lead to diabetes and obesity"?
The last I heard, complex, fibrous veggies (carbs) were the good kind while simple carbs such as rice cakes, white bread, pasta, etc. were the bad kind. ???
The researchers likely failed to look at the fact that our food chain is flooded with omega 6 oils (corn, safflower, sunflower, canola, peanut, and soy) which promote inflammation. Butter, organic lard, beef and the fat on beef, whole milk, cheese, and other dairy, cod liver oil, and coconut oil are historically eaten fats that don't promote inflammation.
Reply | Report Abuse | Link to thisRefined carbs also promote inflammation.
There are many vague, partially-informed, or misinformed and biased comments occurring above. The complexity of cellular and multicellular organisms evolved in environmental conditions unlike those of present cultures, and genetic variation, make such comment extracted from biased short-term limited perusal of popularized, marketed panacea, utterly moot and uninformative.
Reply | Report Abuse | Link to thisInstead, please keep comment to yourselves while you study the research deeply over a period of years, and learn to use scientific method in evaluation.
Thank you all for ceasing to ignorantly comment.
As a non-scientist, I am not qualified to comment on the research that was done. However, as a former wire service reporter (UPI), I do think that the Scientific American reporting is pretty sketchy on several points:
Reply | Report Abuse | Link to this1. Why did the story not have more discussion about the frequent mentions in the original article about the hypothalamus's amazing plasticity and neurogenesis? Forget the high-fat diet. I want to know what nutrients stimulate the development of new brain cells. At age 68, I want more brain cells.
2. Why did the story not give us meaningful details about the diet? Just saying a "high-fat diet" is not very helpful. What kinds of fats? And what about other macro-nutrients? With a higher portion of fats, then the portion of carbohydrates and/or proteins would have been reduced. Could the lower protein or carbs have made a difference?
3. Reducing fat sounds like an odd strategy, considering that the brain needs lots of cholesterol to function. I would be cautious about messing with dietary cholesterol. And what about omega 3 fatty acids? Are we going to throw out the baby with the bath water?
4. The original article kept pointing out that calorie restriction is very effective at repairing neuron damage. Tell us more.
From reading the original research article, I would conclude that eating a (calorie-restricted) high-fat diet would be better than a low-fat diet. Just give me some wild-caught salmon at every meal.
And here's an interesting side note: some of the research was funded by the Picower Foundatin, which had to refund billions of dollar related to their profits from Bernie Madoff's ponzi scheme.
Wishful thinking. The less people know, the stronger their opinions and the greater the likelyhood that they will comment.
Reply | Report Abuse | Link to thisThis is a 60 second podcast. Think about it.
Reply | Report Abuse | Link to thisYeah!
Reply | Report Abuse | Link to thisto all the above.
Dear nancydeville, I can only comment on the paper I authored (the neurogenesis paper) but yes we did not look specific fats such as omega-6. Such work is under way as it is a very interesting topic.
Reply | Report Abuse | Link to thisDear J_buddha,
Reply | Report Abuse | Link to thisYou are correct in that the diets used are not total fat or carbohydrate free diets. In the field High-fat is used for diets higher in fat than normal. It is not a very good term but is better than the previous 'western' or 'cafeteria' which don't really mean anything. In energy usage terms the diets used are basically 50/50 energy from fat and carbs. This ball park figure is called 'high-fat' as it reflects most hunman diets 'high in fat' but not totally fat.
Within the metabolic field, the term ketogenic can refer to both diets which induce a low degree of ketosis (i.e. a high protein diet) or a maximal ketosis (i.e. diets devote of carbohydrate and limited in protein).
I can not say strongly enough that ketogenic has little to do with protein intake. The body can simply convert excess amino acids into carbs making the replacement of carbs by protein of little use. It is the fat to carb+protein that counts. While there are small effects of protein, the '600ib gorilla' is the fat to carb+protein ratio.
Currently I am undertaking a follow up to the this study funded www.action.org.uk having left the Flier lab and I'm addressing some of the issues you raise.
While I can't let all the cats out of the bag, the data so far follows the known effects of macronurtietns on obesity i.e. three different types of diet exist.
1) high carb low fat diets. (normal diet).
2) no carb high fat diets. (ketogenic diet).
3) 50/50 carb/fat diets. (high fat diets).
So yes the data for no carb, high-fat diets is quite different in line with recent research on body weight. If you are interested in the area of ketogenic diets you may find research work in the flier lab of interest. This focuses on the hormone FGF21 which appears to mediate the effect of ketogenic diets. http://www.ncbi.nlm.nih.gov/pubmed?term=flier%20FGF21
Dr D. McNay
Dear Jim,
Reply | Report Abuse | Link to this'I want to know what nutrients stimulate the development of new brain cells.'
There doesn't appear to be a nutrient that does this. Rather it appears to be the combination of high fat in the diet but with plenty of carbs also that inhibits the development of new brain cells.
'And what about other macro-nutrients?'
The changes in hypothalmic damage/repair appears to stem from the combined high fat with suffienct carbs. This appears worse than either diets with almost no fat or almost no carbs.
'I would conclude that eating a (calorie-restricted) high-fat diet would be better than a low-fat diet'
Currently addressing this at the momment. Personally (being a Scot) I am a big fan of salmon espically smoked but I wouldn't personally go for a calorie-restricted high-fat +carbs diets. The science supports a low fat (mainly poly-unsaturated), high carb (but low sugar), moderate protein diet as being best over all when risks off all metabolic issues are balance against each other.
Dr D. McNay
primordialsoupdiet.com