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Good Fat vs. Bad Fat

Good Fat vs. Bad Fat

August 27, 2013

Medical Research

Prof. Iris Shai (Photo: Gali Eytan)

Prof. Iris Shai (Photo: Gali Eytan)

HAARETZ.com — Prof. Iris Shai, of BGU’s Faculty of Health Sciences and S. Daniel Abraham International Center for Health and Nutrition, was recently interviewed in Ha’aretz about her research in the area of nutrition and metabolism.

What are you working on now?

At the moment, we are investigating the dynamics of different fat tissues in the human body, parallel to changes in the metabolic rate, by means of clinical experiments and MRI.

What do you mean by “different fat tissues”? Do we have a number of fat tissues?

Yes. That is what we − and it is my privilege to work with a fascinating group of researchers − are engaged in. Our understanding of body fat has undergone a change. Our group reported that even subcutaneous fat has two distinct and separate layers.

The superficial subcutaneous layer, which is attached to the skin − the one we feel when we are pinched − is healthy.

It is constructed differently and it secretes good hormones. The second layer, the deep subcutaneous layer, is less healthy.

And visceral tissue fat, which exists between the organs, is the most diseased. In other words, if your MRI shows a greater presence of the superficial subcutaneous layer of fat, you are a healthier person.

Even if externally, you look plump.

Exactly. People who store their surplus fat in the superficial subcutaneous fat tissue are healthy people. That is the storeroom that nature has specified for us. Smaller-scale studies show that fatty acid from a vegetal source, such as olive oil, fish oil or nuts, has a greater tendency to be stored there.

In contrast, trans fat, for example, which is a synthetic industrial invention, tends to get stored in the more internal fat tissue, the visceral area.

How bad is it?

It secretes toxins.


Very much so. Just 20 years ago, fat tissue was thought to be dead. Today we know that it is a completely active tissue.

So we have this layer of fat of which we are not completely aware. Doesn’t that mean that the blood tests we do − cholesterol, triglycerides − are out of date as indicators?

No, on the contrary: We are now able to say that there is a close connection between it and the HDL and triglyceride values the tests provide − they are immediate indicators. When we see someone who seems slightly overweight, we have to ask whether he is healthy.

Scientifically, a slightly overweight person who is healthy should eat only healthful foods and exercise by running or walking.

And not start driving the body crazy with diets.

That’s right. He needs to aspire to better results in clinical tests. We know that the human body reaches its maximum weight loss within six months. After that, at best, further weight loss is moderate or the achievement is sustained.

In other words, in a long-term diet, we are already entering the final stretch after six months. The body knows it’s been had.

Four to six months. From about six months the body has been completely challenged; it aspires to return to its original energetic balance and starts to redeploy. The party’s over. Even if we eat the same amount of food, we might start to put on weight slowly.

Does the body always aspire to return to its previous state? Doesn’t it reboot in accordance with the new nutrition?

Regrettably, not really.

Would you say that we are now in a period in which our nutrition is the most calamitous ever?

Not necessarily.

I am referring to the scope of the industrialization and processing, not making a comparison to the Great Famine in Ireland.

From the hunting period until the past 200 years, there has been a natural filtering of modern agriculture toward fruits and vegetables that are less rich in phytochemicals. The reason is that a high level of phytochemicals means sour, very bitter flavors, and the preference in the West is for sweet flavors.

The black corn of the past became a yellow, sweet corn, which contains almost 60 percent sugar. Concurrent with genetic engineering, there is an evolutionary process of fruits and vegetables that aims at nicer looking, longer-lasting items.

Thus, industry is extraordinarily responsible for the increase in visceral fat, and in our children, too.

What are the most ruinous foods? What would you not want your children to eat?

Margarine and its products, and of course sausages. I consider sausages nothing more than preserved cadavers. I would not give my dog sausages. Our children just do not deserve to eat all this industrialized food.

What do you mean when you say industrialized food? Star-shaped schnitzel, for example?

Totally. Is there a food in nature that is star-shaped?

So you would agree with Michael Pollan’s dictum: “Don’t eat anything your grandmother would not recognize”?

Exactly. We habituate our children’s palate to instant gratification. Food has to be immediately sweet, immediately soft, immediately salty.

Our children are exposed to diverse foods in different colors that are produced from four inferior basic materials, the four whites: white flour, white sugar, salt and margarine. What about the foods that come from roots, sprouts and lentils?

That is our fantasy. Children won’t eat those foods.

Our studies showed that situations that are below the boundary norm in childhood are predictors of disease by the age of 45. You don’t have to wait for your child to weigh 120 kilos to know that no good will come of it.

What should we do?

First of all, set a personal example. Second, raise awareness. When a child sees a commercial in which a beautiful model is drinking Coca-Cola, explain that if she really drank it she wouldn’t look like that.

Reflect what we see for him. The child has to understand and be familiar with the criticism. And at the same time, constantly increase the supply of good foodstuffs. There should always be vegetables in a meal, and fruit for dessert.

Even if the child does not eat them. It is essential to invest in the child’s nutritional foundations. Don’t tell him to heat up the frozen schnitzel in the microwave. That’s not fair.

It’s also not food.

We see today that people who eat industrial food have a slower metabolic rate. That causes fattening. So it’s less important to read the package to find out how many calories it says the item has.

You maintain that there is not just one type of calorie, right?

Each calorie reacts differently in the body. The quality is more important than the quantity. Fat cells grow in two ways. There is an increase in the number of cells until the age of 20.

That is known as numerical growth. It is irreversible. From now on, you have that cell. Either you’ll manage to shrink it, or it will enlarge. That’s why the issue of putting on weight in childhood is critical.

Those who become fat before the age of 18 will have to cope with that number of cells their whole life. From the age of 18, it’s a question of size: the bigger the cell, the sicker and less functional it is. It doesn’t work as well as needed and secretes more toxins. We call it an “angry cell.” It becomes bloated and gets irritated, and sometimes it becomes so angry that it explodes. Physically.


Only a few years ago, we discovered that fat cells are not with us forever. They live for something like 10 years.

Fat people produce fat cells at a faster rate, but the mortality rate is the same in all of them. Effectively, the only way to get rid of fat is by liposuction. Now ask me whether that is healthy or not.

I imagine that anything that requires you to lie in bed for a month with a corset is not healthy.

Right. And why? Studies have shown that diabetic women who underwent liposuction did not become healthier.

Because the good fat was sucked out, too.

Exactly. The bad fat is not sucked out.

We should look at fat differently, then; not in an aesthetic context but in a health context.

Thin people who do not eat healthfully, are they healthy? Or our beautiful children − what are we breeding in them?

A sclerotic layer starts to accumulate from the age of four. About 20 percent of fat people are healthy and about 20 percent of thin people are ill.

It’s true that more overweight people are in risk groups for metabolic diseases, but we should be clear that even people who look thin are not necessarily healthy.

Age is also a significant factor.

Definitely. What happens at 17 is not what happens at 37.

That moment when you realize you will never again order pizza in the middle of the might.

Yes. And here too there is a difference between men and women. In women the divide is very sharp. Menstruation stops at menopause, and nature doesn’t need you anymore.

The HDL and estrogen levels decrease and our risk of getting a heart attack increases. Around the age of 50, we narrow the disparity with men in this regard. At that time of life, a woman, even if she is very thin, will have a small stomach of visceral fat.

This is a hormonal and mental divide and needs to be prepared for.


By engaging in sports at an earlier age. By building up the muscle tissue. By looking at Madonna and understanding that the menopausal period is a term from our grandmothers’ era and that we will look good even at the age of 80 if we prepare for it.

This divide does not exist in men. We really don’t see a thing, they fall apart slowly, the testosterone decreases gradually, and one day they have a heart attack.

But we have to understand that the past is history and will not recur. And we also have to set ourselves more realistic goals, because the metabolic rate decreases substantially, so the goals are to maintain one’s existing weight and to be healthy. To eat right.

In the previous study, which we did at the atomic reactor in Dimona…

For which you’re the one who does the studies?

Most of them.

Why there?

My colleague, Dr. Dan Schwarzfuchs, is the director of the clinic there. And they are very strongly health-oriented.


The study at the reactor showed that we can bring about true anti-aging. We proved, for the first time in the world, that it is possible to cause a regression of atherosclerotic tissue, the layer that is immersed in the arteries, by means of a change of diet. Not even a dramatic change. Basic things.

Such as?

The participants in the study stopped eating trans fat and ate as little processed and purchased food as possible. They cooked at home and consumed less salt, less sugar, fewer carbohydrates and more vegetable fat.

They increased their vegetable intake dramatically. Those are the most basic common elements. The result was a loss of weight and lower blood pressure. They also clinically reduced the plaque which is directly related to brain stroke.

It’s like dental plaque, right? It collects in arteries of the body.

And blocks them. If it happens in the coronary arteries, the result is a heart attack. If it’s in the carotid artery, it’s a stroke. The process doesn’t end with those two seconds in the mouth. The harmful food stays with us. Our digestive system is a sophisticated filter, but it cannot do all the necessary filtering.

You urge a return to non-industrial food, home cooking. But the quality of the ingredients is also declining.

This is what we have. There is nothing we can do about that. We live like everyone around us.

Some people live on remote Japanese islands and eat organic nuts. But we are here. We shop in the produce market or the supermarket.

Now we have this anomalous situation, in which healthful food is more expensive.

That’s so. Salmon, nuts, avocado and all kinds of super-foods are expensive. So people tend to eat more carbohydrates.

In general, proteins and the healthy fats are more expensive than the carbohydrates.

Like in the United States: a Big Mac is cheaper than fruit.

Yes. I did my sabbatical at Harvard. That’s a place of people who make a lot of money, and in fact there is no McDonald’s there.

Their branches are located only in poor neighborhoods.

In terms of raw materials, is there any indication by which I can know if a product is healthful? If the bread I choose in the supermarket is really nutritious?

We have few tools for that. The nutrition information panel is inadequate and is not sufficiently enforced.

And when it’s checked in a laboratory, it turns out to be incorrect.

True. There is an allowed margin of error of 20 percent, and there are no tools for an adequate enforcement policy.

You get products which do not contain cholesterol to begin with labeled “cholesterol-free.”

Exactly. It’s like writing on a car that it doesn’t contain cholesterol. It’s misleading the public. You reach the lowest common denominator.

When a snack bar claims to have “added vitamins and no cholesterol,” the ordinary person has no tools to realize that this is only a wrapper.

In nutrition, as in medicine, we have this phenomenon of studies that are published and make waves, and then another study appears that contradicts their conclusions completely. Is there some absolute truth?

The day when we start using exclamation marks in science will be the day when research stops. A good researcher has to draw the conclusion and present it with a great deal of modesty and also with a few question marks.

The problem with nutrition studies is that it’s like popular science. Sexy newspaper headlines: “Researchers from University of Virginia say bitter chocolate prevents cancer.” What should I look for in the body of the article in order to know if that’s true or mere nonsense?

The more solid studies consist of follow-up research projects that go on for decades among tens and hundreds of thousands of people. The highest level is long-term, thorough controlled clinical experiments.

Though even then mistakes are made. Second, you need to check where the study was published, in which scientific periodical, if at all. It’s also important to check if there were other studies that came up with the same findings afterward.

A finding that was examined only once is not enough. If the medical phenomenon is correct, it has to be reported many more times.

What about funding for research studies − the corporate interest?

That aspect is somewhat more regularized today. Every researcher who wants to conduct an experiment has to register with the Center for Research Studies Control in the United States and report on who is responsible for the funding and how involved he is, if at all.

Do you think nutrition should be guided by policy directed from above?

Absolutely. The government is the responsible adult. And I expect that one day it will happen.

What would you like to see happen?

A long-term strategy from birth, everywhere. Regulation, truth in advertising, laboratory tests responsible for finding out what is in the food, price reductions of the good foods, taxation.

There is a whole host of things to be done, but we have to take the long-term view. It’s important to understand that what you invest now in a 1-year-old infant is what you will see 50 years down the line.