Fatty Diet May Thwart Brain's Fullness Signal

[nobimbo]

Fatty diet may thwart brain's fullness signal
Mon Aug 8, 2005 8:36 PM BST
By Amy Norton

NEW YORK (Reuters Health) - Rats that are fed a high-fat diet appear to lose their sensitivity to a hormone that tells the body when it's had enough to eat -- and the same could be true of humans, according to researchers.

In experiments with rats fed either a high- or low-fat diet, researchers at Pennsylvania State University found that the fatty diet diminished the rodents' sensitivity to a hormone called cholecystokinin, or CCK.

CCK is secreted by the small intestine to aid in the digestion of fat and protein. It is also one of the "satiety signals" that the body produces to tell the brain that it's time to stop eating.

In the new study, rats on a low-fat diet stopped eating a fat-filled treat when the researchers gave them a dose of CCK. Not so of the animals on the high-fat diet, who ended up eating far more of the fatty snack.

The findings suggest that consistently eating high-fat foods can desensitize the body to CCK's signal to stop eating, according to Dr. Mihai Covasa, an assistant professor of nutritional sciences at the Penn State campus in University Park.

There is reason to believe that the findings in rats translate to humans, Covasa told Reuters Health. He pointed to a study that found that people who followed a high-fat diet for 2 weeks gradually became less satisfied from eating fatty fare -- suggesting that, in the real world, they would have started eating more.

Covasa and colleague David M. Savastano report their findings in the August issue of the Journal of Nutrition.

Rats in the study were maintained on either a high-fat or low-fat diet for 3 weeks. When they were then tempted with a fatty snack, the animals that had lived on the high-fat diet ate more of the treat than those on the low-fat diet. And when the researchers injected the animals with CCK, they found that the hormone suppressed the low-fat group's appetite over the next hour, but not that of the high-fat group.

The findings, Covasa said, underscore the importance of minding one's fat intake, and of fitting a variety of foods and nutrients into the diet.

"You should watch how much you eat," he noted, "but the composition of what you eat is important too."

SOURCE: Journal of Nutrition, August 2005.

http://today.reuters.co.uk/news/newsArticle.aspx?type=healthNews&storyID=2005-08-08T193624Z_01_N08345779_RTRIDST_0_HEALTH-RATS-DIET-DC.XML

[CindySue48]

Rats that are fed a high-fat diet appear to lose their sensitivity to a hormone that tells the body when it's had enough to eat -- and the same could be true of humans, according to researchers.

That's all I needed to read. :yawn:

What difference does it make how rats react? There are plenty of studies that show fat helps PEOPLE feel full faster AND for longer periods of time! Are there really people who will read this and decide this is the evidence that convinces them (or reinforces their belief) that fat is bad?

[ItsTheWooo]

Perhaps this is as intended, not a failing of fatty diet.

A theory:
Fat stimulates more CCK because it is needed to break it down in digestion. Ironically, that's a reason fat is satiating and carbs are not.
An unexpected rise in the anoretic hormone CCK relative to past trends, from eating more fats & less carbs, even when energy of diet is the same or less as it was before, will result in spontaneous under eating. This is one of a myriad of reasons many of us (particularly those who are hyperinsulinemic when eating carbs, as we probably produce LESS CCK than average people since our bodies have a hard time facilitating protein/fat catabolism due to the insulin) find it so much harder to eat the more we replace carbs with fat. More fat, more CCK (and if you were hyperinsulinemic it may very well be dramatically more), less hunger (again if hyperinsulinemic, dramatically less), & less food intake often well below maintenance of size.

Now, perhaps lowering sensitivity to CCK is a part of the body's adaption to the high fat diet. If we assume the healthy body wants adequate energy (a reasonable assumption), and if we assume the body is using more fuels that have an extremely high "satiety response" (fats), isn't it also reasonable to assume the body will decrease sensitivity to these anoretic, catabolic hormones so that we don't malnourish ourselves? This would likely be a temporary insensitivity, not from system malfunction (like say insulin resistance), but as an adaptive mechanism to a new kind of diet (fat). If this theory is correct, the insensitivity (or sensitivity) is in flux, and is dependent upon how active catabolic hormones are, how few carbs. It should be a reversible state if one returns to high carb eating.



This is just COMPLETE conjecture on my behalf I have absolutely no idea if it's correct or not... but IMO it is irrational to assume that eating more fat will make the body want more energy for no reason at all. In insulin resistance/hyperinsulinemia we see this occurring because the insulin resistance is creating a malnourished/wasting state by in which the body can no longer effectively use fats and proteins for fuel (and eventually sugar as one falls into diabetes). What would be the logic behind increased hunger when eating more frequently from fat, if the rats were otherwise healthy and asymptomatic on their high fat diets?

[ItsTheWooo]

Either way, one thing is certain...

Carbs break a lot of human being's metabolisms.
Carbs make it hard to use energy from fat, from protein, and eventually later on from sugar. On a carb diet we humans are rendered acutely or chronically ill with physical, mental, and emotional lethargy/lowness. Even in extremely small children with healthy elastic young sugar metabolisms not yet weathered from insulin insensitivity, even they experience crashes of some magnitude after their breakfast of jam and toast.

Because this is a truth...
Having a broken metabolism also break's food seeking impulse & behavior.
If your body is starved for energy, it will cause a hormonal cascade that makes you want to EAT all the time. That's to be expected.

So, if it is true that carbs are known to cause metabolic disease in humans, and if it is true that metabolic disease naturally yields the symptom of increased hunger...
Isn't it likely that fat (a "neutral" fuel, a fuel who's fate depends primarily upon the state of carbohydrate in the body) is likely better for us than carbohydrate?

[TheCaveman]

What we know for sure about CCK in the human body is that it sends a satiety signal relative to the amount of fat in the intestine. The more fat you eat, the stronger the signal. Makes sense, eh?

CCK is also the mechanism by which fat delays gastric emptying. This is why a potato is going to hit your blood sugar harder than a potato with butter and sour cream and bacon bits.

But they've been burned on CCK before when trying to run human studies. When they first figured it out that injected CCK sends a satiety signal in mice, they thought they were on to something. They think to themselves, hey, if we inject CCK into people, it should reduce appetite, right?

Nope. While food-induced CCK reduces appetite in humans, injected CCK was found to be neutralized by an enzyme in the pancreas.

Cholecystokinin and secretin releasing peptides in the intestine. A new regulatory endocrine mechanism in the gastrointestinal tract. Herzig KH. Regul Pept 1998; 73:89-94.

It seems that this enzyme action (they believe somatostatin) keeps us from vomiting our food by neutralizing CCK. Mice were found not to exhibit this reaction. No mention of how often the mice barfed in the new study?

Bad news for the protein powder crowd, I guess.

[K Walt]

Huge flaws in this:

1. They're rats.

2. They're recommending that you NOT eat a fatty diet, to maintain your sensitivity to CCK. Trouble is, if you eat a non-fatty diet (read 'carby') you won't be eating fat, and won't be releasing the satiety hormone anyway. You'll just keep on eating the carbs, and eating and eating and eating.

[tuscany]

I am kind of agreeing with the study; after the initial weeks, I definitely want more food, regardless of the fat in it. Or maybe its due to increased carbs ?

[TBoneMitch]

After a high fat breakfast, I find I am able to easily go 5-8 hours without eating at all without any discomfort.

And as was said, fat in the small intestine is the most powerful signal for CCK secretion.

I see another flaw in the study: it is not specified what % of fat composed the high fat diet.

Often, a high fat diet is only like 40-50% fat, leavinf 40-50% carbs.

So in fact, a high fat diet in such studies is actually a high fat, high carb diet, which will indeed supress appetite control signals because the sugars and carbs blunt the appetite supressing effects of fats (ex: an ince cream binge, or a cheesecake binge, etc.).


Worthless propaganda.

[Nancy LC]

My experience has been that whatever I'm eating the most of fails to keep me satisfied. So when I was doing 70-80% fat, eventually I started eating more fat. When I was doing mostly carbs... well, we all know that one. I think that the protein is actually working the best for me in that area. If I have a slab of lean meat, it pretty much kills my appetite for a long time.

But what's weird is how different even proteins are. Cottage cheese wears off very, very quickly for me. My low carb, NF yogurt sticks around. Meat sticks around. Eggs stick around. Satiety is weird. Why do pickles make me fuller than cucumbers?

[Wyvrn]

Why do pickles make me fuller than cucumbers?Pickles have fat in them from the fermentation... maybe enough to make a difference?

Wyv

[Dodger]

I jsut checked the USDA database and pickles have 0.19 fat grams per 100 grams, while cucumbers have 0.11 fat grams per 100 grams.

[Nancy LC]

Where would the fat come from? Maybe just because it is a different sort of cuc than the type you eat raw... still, that isn't much fat... .08 grams. Wouldn't even be one calorie's worth.

[ItsTheWooo]

Fermented cucumbers (pickles) are acidic foods, which can help reduce glycemic load of a meal, which can help reduce need for insulin, which would allow your body to use energy better and decrease hunger. This is true of all acidc & fermented food products. That's one theory.

Another theory is the the sour tartness of a cucumber blunts snacking impulses. We confuse cravings with hunger. It's not our fault, hunger makes us sensitive to cravings so after awhile we start to think craving is the same thing as being hungry (even though it's not and it's possible to crave a food sensation though physically full). Result? Habitual over eating. If you're carb sensitive you can really do a number on your weight this way. The carbs make you hungry all the time, the hunger makes you crave, so you become heavy quickly.

In my experience it also works in reverse. You can manipulate our bodies confusion between cravings and hunger to our advantage. When on a weight loss diet I find it is very possible to satisfy cravings and (at least temporarily) make your body think it has satisfied hunger.

Often times I'll find something about a food in taste or texture will nip appetite, whereas other food tastes and textures will open it.
Carb controlled, sweet foods often satisfy me. I am a salty/meat craver, so this makes sense as sweet food "washes" my palate of the salt/meat taste (which I am so very fond of and can lead to impulse control problems with food). Often times I can avoid myself binging on meats (yes I CAN do that) by eating a small bowl of acidic yogurt with AS berries and nuts. Most people are sweet cravers so they find the opposite true. To avert binges they will eat something pungent and meaty like a cucumber or a small bit of leftover dinner.

They say a pickle is a good way to suppress your appetite, but this is probably true mainly in the sweet/carb craver. The intense pungent vinegary taste of the pickle makes you adverse to the more mild tastes. Your craving for food goes down.
Interestingly I find pickles to be a fun snack, good to eat when you want to mindlessly munch, but they don't affect appetite much either way.

I find the extremely heavy, fatty, thick sensations of many low carb foods to be potent appetite suppressants too. It's interesting that this is true not the fat itself but the feeling of thick/heaviness in a meal. "Fat like" substances such as polydextrose, plant gels, and goopy thick concentrated protein solutions in diet products work just as well as say, peanut butter or cheese... but for less calories. I think my body interprets that "oomph" and "bulk" of heavy fat-like substance as a concentrated source of energy, so snacking & food intake impulse is blunted for awhile thereafter. I think tastes and textures of consumed substances (even if non-energetic) tell our bodies to do things to hunger, because our bodies have primitive associations between tastes/textures and various types of nutrition.

[DietSka]

Just a thought: if they're canned using vinegar, vinegar is a lipid.

[ItsTheWooo]

Just a thought: if they're canned using vinegar, vinegar is a lipid.

How is vinegar a lipid?
Vinegar does things to reduce glycemic load of a meal, which is a boon for metabolic health... but vinegar is not a lipid.

[Groggy60]

In the new study, rats on a low-fat diet stopped eating a fat-filled treat when the researchers gave them a dose of CCK. Not so of the animals on the high-fat diet, who ended up eating far more of the fatty snack.

Doesn't that prove giving doses of CCK don't work as well with fat. I never get very full on carbs, where is that study?

[Nancy LC]

I haven't ever had trouble distinguishing between hunger and cravings. Hunger is a very physical sensation in my tummy. Its either growling and rumbling or a slightly painful burning. Its definitely physical. A craving is just a desire to eat a particular item that may or may not have anythign to do with hunger. Sometimes when I'm hungry my cravings are worse. But usually a good dose of protein put that's right down.

There's definitely something funky about food satiety and I think it is more complex than simply fat, carb or protein content.

[Wyvrn]

Just a thought: if they're canned using vinegar, vinegar is a lipid.Bingo - whether canned in vinegar or naturally fermented (in which case they make their own vinagar). Vinegar (acetic acid) and other products of bacterial fermentation including butyric acid, lactic acid and citric acid are short chain fatty acids. Fatty acid production via bacterial fermentation is how cattle and other ruminents extract energy from cellulose which is their primary diet.

Wyv

[ItsTheWooo]

Bingo - whether canned in vinegar or naturally fermented (in which case they make their own vinagar). Vinegar (acetic acid) and other products of bacterial fermentation including butyric acid, lactic acid and citric acid are short chain fatty acids. Fatty acid production via bacterial fermentation is how cattle and other ruminents extract energy from cellulose which is their primary diet.

Wyv

Ok I'm confused...
If these acids are fats how come calorie counters list vinegar as being fat free? The only energy contained comes from a negligable amount of carbs.

[Dodger]

Well vinegar is definitely a fatty acid, much to my surprise. http://www.x-ald.nl/biochemistry.htm (scroll down just a little).

While looking for the fatty acid info I came across this very informative biochemistry set of pages. http://web.indstate.edu/thcme/mwking/home.html

[Nancy LC]

That's just... just... just... weird!

[ItsTheWooo]

Oh wow, I apologize... learn something new every day.
So if acids in vinegar is a SCFA does this mean it actually has way more energy than we thought? Or, is there so little energy (fat) in the vinegar that it's negligable and therefore the calorie counters were right all along?
Is the fat the reason acids are known to lower glycemic load of food?

[Wyvrn]

The concentration of acetic acid in distilled food grade vinegar is low enough that it probably doesn't meet the minimum for reporting in a serving. If I have the math right, in the typical 1 Tb serving of vinegar that would put the calories from SCFAs at about 4 (~7 calories per gram for SCFAs). Pickles would have more mass per serving but probably much lower concentrations of acetic acid than plain vinegar.

Acetic acid and other SCFAs found in fermented foods are saturated, so there is also an incentive for commercial producers to keep it under the reporting minimum, though I think this is unlikely to be necessary due to the low concentration.

Either way, cukes and other non-starchy veggies are low-energy to begin with and the conversion of sugars and starches to SCFAs via fermentation results in a net loss of energy. Of course, this is not true for vegetables that are canned in vinegar, as most commercial "pickle" products are, rather than fermented.

Wyv

[Nancy LC]

Acetic acid in white vinegar is 5%, rice wine vinegar is around 4-ish. I remember this from a Good Eats episode that got me all excited about pickles. :p

[PilotGal]

After a high fat breakfast, I find I am able to easily go 5-8 hours without eating at all without any discomfort.

Oh, here too... Nothing sucks more than eating a breakfast, and 2 hours later, being starved. I prefer to feel satiated for a few hours, at least until I can break away and have lunch......


And as I've said before..... the brain is 78% fat. Without fat to your brain, you're doing yourself a disservice when old age hits.