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If you're one of those people who
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needs to make a huge effort to avoid
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gaining weight, you've probably
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felt a bit envious of those who can eat whatever they
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want and never get fat. In
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our case, everything seems to be heading straight for the
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Michelin Guide. The culprit seems to
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be metabolism, an expression that
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encompasses various factors, including
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our ignorance. But let's start
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Overweight, the older sibling of
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obesity, has increased alarmingly
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in the Western world in recent
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practically epidemic levels. This problem is
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overweight and obesity increase the
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predisposition to suffer from a wide
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variety of diseases, so it's
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important to understand the causes of this
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epidemic. Obviously, there are
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important nutritional factors, but these are
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relatively well-known. On the other
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hand, there are the genetic factors
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involved in the development of
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obesity, which are less well-known. Hence,
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in recent years, researchers and
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scientists have focused on
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identifying the genomic variants that
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increase the tendency towards being overweight. The
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curious thing is that no one had found
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evidence that diet alters
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What we eat can modify our
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DNA. I know, it sounds crazy, but let me explain. It
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all happened in the summer
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of 2008 when a group of
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researchers from the United States and the
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Netherlands demonstrated that the children of
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women who had been subjected to
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food rationing during
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pregnancy show traces in their genome.
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more than half a century, this is
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very important, and later you will understand
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the repercussions it will have in the
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medical field and in our society. Going back to
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the study, yes, the research that was
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done is somewhat murky and is linked
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to a very important event in the
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history of humanity. So
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hold on tight, because it's going to be intense.
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Near the end of World War II,
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part of the Netherlands came under
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German domination and suffered
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severe food rationing. There was
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famine. This grim episode is
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known as Hangar Winter (
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Hunger Winter in Dutch) and lasted until
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May 1945. The researchers
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analyzed the genome of 60 individuals
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who were conceived during the months
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of famine, along with another 60 people
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whose pregnancies were already quite
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advanced when rationing began.
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Surprisingly, they found a
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fetal growth... It still shows some alterations
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after several decades. The gene in
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question is called igf2, and scientists
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saw that its function varies with
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methylation. For those unfamiliar with
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this terminology, simply put, it
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of a methyl group to DNA, which causes
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a decrease in the expression of a
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particular gene. So, the results
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of this research showed that
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individuals conceived
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during the famine have
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very little methylation in the igf2 gene today,
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indicating that maternal malnutrition
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during pregnancy altered the
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children's genome in an attempt to
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compensate for that calorie deficit. They realize
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this, and the incredible thing is that
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this alteration has been detectable after
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Furthermore, this effect was not observed in the
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case of women whose pregnancies
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were already advanced when
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the food shortage began,
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demonstrating that the alteration of the
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genome only leaves a trace if it occurs
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in the early stages of gestation.
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This new work reinforced
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quite conclusively that some
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environmental influences experienced by the
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mother during pregnancy affect the
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embryo and can be reflected in its
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You realize this is very powerful, but not
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only in its genome because it seems that the
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fat ingested by the pregnant mother
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also leaves traces in the brain of the
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offspring. At least, this is what
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a study carried out by
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Rockefeller University in New York suggests, which was
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published in the Journal of
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laboratory rats, the scientists demonstrated
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that consuming a high-
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fat diet during pregnancy causes
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certain changes in the fetal brain, such that
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when they are born they eat more
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than normal. To verify this,
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they fed one group of pregnant rats
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a high-fat diet and the other
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group of animals a standard diet. When
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studying the brains of the
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offspring, both groups observed
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that the animals born to the rats
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fed a high-fat diet had a
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greater amount of substances in their brains
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that increase appetite.
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Furthermore, the offspring of these rats
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developed over time a
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higher than normal intake, with a
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special preference for diets—
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you guessed it—high in fat, which leads to the well-
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known hyperlipidemia, which is an increase in fat
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in the Blood and also
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overweight: these effects persisted at
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least until day 70 after
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birth, which corresponds to what would be
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the end of puberty in humans.
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This is extraordinary because
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appetite regulation is quite
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complex and sophisticated, requiring the
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coordinated production of many
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molecules in specific
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brain regions—substances with
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beautiful names like orexin, galanin, or
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dynorphin—which are responsible
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for making us feel hungry when we see something
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appetizing or in response to
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stimuli from the stomach or
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blood. It's difficult to explain how
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exposure to a high-fat diet
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can alter these processes for
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so long, but in any case, this
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work demonstrated that some
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maternal situations during pregnancy can be
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the cause of overweight in
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offspring. Considering the
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childhood obesity epidemic the world is experiencing
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today, this data would have
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enormous relevance if it is
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confirmed that the same thing happens in humans.
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Very important note: these studies were
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carried out on rodents. But this is not
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all; it's just the tip of the iceberg. What we just
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talked about in this video regarding
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the influences of the environment on
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genes is known as epigenetics.
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Methylation and acetylation can
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silence or overexpress
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certain genes, resulting in
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changes in the behavior of some
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individuals, such as the "
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good mothers" or "bad mothers" in our society.
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But we'll talk about this in another video.
