How Does Soy Promote Weight Loss?

[Judynyc]

How Does Soy Promote Weight Loss?

http://www.sciencedaily.com/releases/2007/05/070501115010.htm


Science Daily — Research shows that when soy consumption goes up, weight goes down. A new University of Illinois study may help scientists understand exactly how that weight loss happens.


"We wanted to compare the effects of soy protein hydrolysates and soy peptides with those of leptin because we hypothesized that soy might behave in the body in a similar way. Leptin is a hormone produced in our adipose tissue that interacts with receptors in the brain and signals us that we're full so we stop eating," said Elvira de Mejia, a U of I assistant professor of food science and human nutrition.

The researchers wanted to see if soy protein hydrolysates could affect these regulatory hormones and their receptors. "And we found that soy did have an effect on these mechanisms and hormones that are induced in the body to help us degrade lipids and reduce body weight, but it did so by boosting metabolism and not by reducing food intake," she said.

To compare soy peptides with leptin, de Mejia's graduate student Nerissa Vaughn, with the help of associate professor Lee Beverly, implanted cannulas in the brains of lab rats; they then injected leptin as a positive control. When the scientists could see their model was working, they injected two formulations of hydrolyzed soy protein and soy peptides so the scientists could monitor the effects of each on food intake and weight loss.

Injections were given three times a week for two weeks; during that time, the animals had unlimited access to food and water. Food intake was measured 3, 6, 12, 24, and 48 hours after injection, and the rats were weighed 24 and 48 hours after injection. All rats received the same amount of exercise, and all rats lost weight.

But, after the third injection, de Mejia and Vaughn noticed a significant weight loss in the group of animals that had received one of the soy hydrolysates, even though the animals hadn't changed their eating habits. In this instance, soy protein appeared to have caused weight loss not by reducing food intake but by altering the rats' metabolism.

The experiment not only showed that soy peptides could interact with receptors in the brain, it also demonstrated that eating less isn't always the reason for weight loss, the researcher said.

"Weight loss is a complex physiological event. It's not always as simple as 'Eat less or exercise more,' said de Mejia. "Losing weight is a cascade of many steps, beginning with the production of certain hormones and continuing with their action in the brain. Some people are resistant to these hormones, just as other people are insulin-resistant. These people never receive the message from the brain that tells them they're full," she added.

de Mejia plans to continue investigating the effects of soy proteins on weight loss. She believes soy contains anorectic peptides that signal a feeling of satiety as well as peptides that boost the metabolism. Her next step will be to fractionate and purify the soy hydrolysates so that she can identify each peptide and understand its bioactivity.

de Mejia and Vaughn presented their findings Sunday, April 29, at the Experimental Biology meeting in Washington, D.C. The study was funded by the Illinois Soybean Association and SAI Company.

Note: This story has been adapted from a news release issued by University of Illinois at Urbana-Champaign.

[Gostrydr]

Boy these guys will say anything to promote this garbage..

Next it will be the panacea for ADD,Autism,Alzheimers and jock itch.

[Michelle H]

Hmm, I wonder if the researchers considered that injecting foreign matter into rats' brains might actually poison the animals and that is why they lost weight?

Does PETA know that animals are suffering in soy trials? Shame.

[evenik]

First, consumption of soy decreases the amount of free (unbound) thyroid hormones in the blood. It can actually make you slightly hypothyroid.
Second, eating soy is different from getting soy injections in your brain.
Third, how is that for an unbiased study:

de Mejia and Vaughn presented their findings Sunday, April 29, at the Experimental Biology meeting in Washington, D.C. The study was funded by the Illinois Soybean Association and SAI Company.


And they jump to a conclusion that soy causes weight loss??? I don't think so.

[Abd]

To compare soy peptides with leptin, de Mejia's graduate student Nerissa Vaughn, with the help of associate professor Lee Beverly, implanted cannulas in the brains of lab rats; they then injected leptin as a positive control. When the scientists could see their model was working, they injected two formulations of hydrolyzed soy protein and soy peptides so the scientists could monitor the effects of each on food intake and weight loss.
Okay. But ... note, they are comparing the effect of injecting soy protein with the effect of injecting leptin.
after the third injection, de Mejia and Vaughn noticed a significant weight loss in the group of animals that had received one of the soy hydrolysates, even though the animals hadn't changed their eating habits. In this instance, soy protein appeared to have caused weight loss not by reducing food intake but by altering the rats' metabolism.
Wait a minute. The experiment was designed to compare the effect of leptin with that of soy proteins. Along the way, they discovered an apparent effect that the experiment was not designed to test. Such findings can be very interesting, and can lead to experiments designed to test the hypotheses that might be formed as a result, but "appeared" is actually the correct terminology. However, there could well be other explanations. Maybe the protein isolate made them sick. Maybe it gave them diarrhea. Maybe they aren't telling us the whole story. Maybe those animals died the next week. Would they tell us? Maybe, maybe not:
The experiment not only showed that soy peptides could interact with receptors in the brain, it also demonstrated that eating less isn't always the reason for weight loss, the researcher said.
Didn't we already know that? Further, as described, the experiment does not show that soy peptides interact with "receptors in the brain." At least, if it did, the reason to believe that was not described. As described, they found that the mice with the soy isolate injections lost weight. How does this show interaction with brain receptors? That would be an effect of less appetite. But the animals did not reduce intake, so there was not less appetite.
"Weight loss is a complex physiological event. It's not always as simple as 'Eat less or exercise more,' said de Mejia. "Losing weight is a cascade of many steps, beginning with the production of certain hormones and continuing with their action in the brain. Some people are resistant to these hormones, just as other people are insulin-resistant. These people never receive the message from the brain that tells them they're full," she added.
All very interesting. Iindeed, the Atkins diet is based on some of this. Fat is the appetite suppressant. So, by the way, to a lesser degree, I think, is protein. So is it soy protein or would other proteins have a similar effect? Why did one soy isolate cause the effect and not the other? What was the sample size, was it large enough that the variations between the groups might not be causal? Lots of questions, not very many answers. But we do not have to look too far:
de Mejia plans to continue investigating the effects of soy proteins on weight loss.
Why soy proteins? W ... e ... l ... l ...
The study was funded by the Illinois Soybean Association and SAI Company.
One of the great dangers in science is when you run a set of experiments with some agenda; for example, to find some beneficial effect from ... soy protein. So you do this and you do that and eventually you find, in some study group, some beneficial effect. But this could be an artifact of your search. Each study group will have some statistical variation in it. If you do a hundred studies of the same thing, particularly if the sample sizes are small, you will get some results that appear astonishing! Until you realize the sample series that they were part of.

This study would properly be characterized as exploratory. It's perfectly legitimate for a soy company to fund research looking for possible benefits of their product. What gets dicey is when unconfirmed research is presented in a way that makes it look like something has been demonstrated, when, in fact, there is merely a clue that *maybe* something is happening. Then one, properly, designs a study to test that. How does soy protein isolate compare with other protein isolates? If over many comparisons, there is found to be a significant superiority of soy protein isolates in having some effect, what, then, is causing this? One would try different fractions of the isolate. Etc., etc.

But to draw big conclusions about diet and the rest is, shall we say, outside the scope of what the experiments showed. The conclusions themselves, as presented, have very little to do with soy isolate, and the connection between what soy isolate *might* do and leptin is ... thin!

I just can't get over it. If soy isolate functioned like leptin, it would suppress appetite. And yet they still seemed to think that they showed that soy isolate had an effect on "brain receptors."

But who am I? Certainly not an expert!

[Absinthe62]

I'm sure all the vegetarians in the world will be thrilled to hear how their beloved soy is being used to torture lab rats. Many became veggies because they couldn't stand the thought of animal suffering. Now this...

There must me major $$$ in the soy industry since they promote the crap constantly. It's in most every "high protein" breakfast cereal on the shelves, soy oil is in most dressings... it's becoming as ubiquitous as HFCS.

May the Gods save us from ourselves.

[athena11]

I didn't see that the soy industry promoted the study!!!

[Nancy LC]

Well, the study was done at a university and they've usually got pretty good rules about funders not interfering in how the money gets used. I remember a big dust-up over Merck giving Stanford money then complaining that one of the professors was dissing their drug. Stanford stood up for the prof and Merck was royally embarassed in the ensuing media coverage.

I think academic studies are probably one of the sources we can still trust.

[kaypeeoh]

When researchers publish dramatic findings, instantly other researchers try to replicate the study. If they can't, it puts the first researchers in a bad light. That's the main reason why researchers try to follow scientific guidelines. They don't want to look bad, they don't want to lose their credibility. Don't take as gospell one research finding. Wait til you can see three or more similar findings from other studies.

When I was in college a masters candidate did a study of LPS (lipopolysaccaride) in the cell walls of e. coli. He concluded the saccaride was responsible for disease in lab rats. When I repeated his study I found saccaride was not even a minor factor. The lipo faction was what killed the lab rats. That's now been proven over and over.

[Abd]

Well, the study was done at a university and they've usually got pretty good rules about funders not interfering in how the money gets used.
I think academic studies are probably one of the sources we can still trust.

To a degree. I don't think that my point was noticed. If you give a university money to study the effects of your product, and you are reasonably confident that they won't come up with a conclusion that it's poison, the odds are that they might discover some phenomenon in connection with the use of the product that is allegedly salutary.

It's a reasonable assumption that someone in the soy industry, knowing that protein generally suppresses appetite, might fund research seeking to discover if *soy protein* suppresses appetite. Odds are that it would. Now, the *real* question is whether or not it actually does this *better* than other forms of protein, and, indeed, than fat. High-protein diets are probably dangerous, whereas many of us think that high-fat diets are not. And that high-fat diets also lead generally to weight loss, quite possibly because of appetite-reducing effects as well as the alleged metabolic advantage. I think that protein also has a metabolic advantage over carbohydrates as well.

(By the way, metabolic variations are supposedly built into the system of reporting caloric content, a fact that seems to not be well-known, as can be known by supposedly informed experts claiming that "a calorie is a calorie," and that the idea you might lose weight on one diet rather than another, if both ideas had the same number of "calories", is somehow a violation of the laws of physics. It's astonishing that nutritionists don't seem to know how calories are actually determined! It is not simply with a bomb calorimeter, which will determine true combustion calories. There are compensation factors which are used to determine *effective* caloric content, based on studies done a long time ago. But those factors assume that dietary context is irrelevant. Apparently it is not irrelevant. How much of a food is effectively used by the body depends on what other foods are being eaten, it appears, plus there is also the issue of how rapidly a food of a particular caloric content is digested. It's *complicated*, folks!)

In any case, the reported research was really only an exploratory study and should not be considered as having proven anything. Such a study would be a guide for further research, and neutral research would not necessarily focus on soy protein alone. But will the soy industry fund studies of, say, milk protein or, as well, saturated fats?

Think about it. Suppose you fund a study that compares soy protein with a saturated fat, and the study comes up with the result that the fat is much better and, let's make it even stronger, safer. You just paid to have your industry seriously damaged. No, I don't think you would do it.

If you are seriously interested in food research, rather than in promoting your own product, you could contribute to the overall budget of a research institution. But, from what was in the study, it was only the specific study that was funded.

In this case, the matter is even worse. The study was apprently designed to test a particular hypothesis, but, along the way, they noticed something else. This happens all the time, particularly when the study samples are small, without there being any particular real phenomenon behind the result, it happens because of normal statistical variations. This is why good studies never draw conclusions about things they were not designed to test.

It might seem like the result is statistically significant. However, statistical significance assumes that the there were controls, that the reported phenomenon was not merely something else noticed.

Think about it this way. Have you ever seen these comments about "amazing number coincidences?" We see some correspondence of numbers that is just too striking, we think, to be a coincidence. There must be something behind it. The problem is that there are millions of combinations of numbers that we might look at and say that "Wow!" We do not see, essentially, the true population, which would be the population of all possible number combinations and the ones that look like amazing coincidences. What percentage of the former are also in the latter class. A lot of them!

*Any particular one* may be extremely unlikely, but we did not set out to look for that particular one. Indeed, we weren't looking at all, except maybe for "something unusual or unexpected."

And that is what happened in this study. It is actually an elementary phenomenon that researchers are supposed to understand, which is why I'm a little skeptical about how well supervised this research was. It's not that the study is a problem in itself, it is that the report of the study drew unwarrranted conclusions.

[Abd]

When researchers publish dramatic findings, instantly other researchers try to replicate the study. If they can't, it puts the first researchers in a bad light.

That's how science works. However, the danger to the first research is not in reporting his or her results -- presuming that they weren't faked or from a poorly designed experiment. It would be in the *conclusions* drawn. If the researcher finds something interesting, it is not dangerous to report it and, even, to suggest that this might indicate something, if it can be confirmed. It is in claiming that the study proves something that it does not prove that a researcher's reputation could suffer.

When I was in college a masters candidate did a study of LPS (lipopolysaccaride) in the cell walls of e. coli. He concluded the saccaride was responsible for disease in lab rats. When I repeated his study I found saccaride was not even a minor factor. The lipo faction was what killed the lab rats. That's now been proven over and over.

Right. His error was the conclusion, not the experimental result -- though there could have been problems with the experiment as well. He found an apparent correlation, I'd assume, which will then suggest the need for confirmation or further exploration, hopefully with tighter experimental design. Exploratory research will not generally have tight design, because tight design seriously limits what you might discover. But you have to understand that opening yourself up to new discoveries also opens you up to results that don't stand up to verification.

The unsung heros of science are all those who did experiments that were well designed and which found nothing of interest. It's actually quite important that all this work be published and available. That is one reason why the suppression of negative results in research funded by drug companies is so offensive. It warps and distorts our knowledge in favor of concluding that a particular drug works, and it wastes the knowledge gained through all those boring experiments.

There needs to be a Journal of Boring Experimental Results that will publish anything from well-designed experiments. Sometimes, when some proposal has been made, experiments designed to verify it that get negative results will be published. But raw research, not so much. The internet makes it more feasible for this vast body of "uninteresting" research to be effectively published and searchable.