This article discusses how fructose increases body fat in the human body and how it acts as our fat switch.
The theory that fructose generates a signal for the body to start making fat is based on research by Professor Richard Johnson of the University of Colorado Anschutz Medical Campus (and author of the book The Fat Switch).
Professor Johnson made several discoveries about fructose by looking closely at animals in nature.
Read on and discover the effect fructose has on fat storage in our bodies.
Table of Contents
- 1 How animals regulate fat storage
- 2 Fat storage syndrome versus metabolic syndrome
- 3 Survival of the fattest in the animal kingdom
- 4 How exactly does the fat storage system work in humans?
- 5 Evolution increased uric acid and introduced a new taste
- 6 What foods and drinks contain umami in natural form?
How animals regulate fat storage
Professor Johnson is an enthusiastic scientist who often cannot suppress a chuckle or laugh while explaining.
He describes his own style of scientific investigation as creating a kind of detective story in which he makes several discoveries that lead to an interesting theory. His theory around fructose was developed in this way.
For example, he discovered that several animals, from insects and bears to whales, can regulate their fat percentage. In practice, this sometimes results in doubling their normal weight.
Think of the shiny grizzly bears or waddling penguins taking center stage in countless documentaries. These animals are twice as big in winter as they are in summer.
For example, this is how bears prepare for their hibernation in winter (called hyperphagia in technical terms).
Grizzly bears have an annual cycle of hyperphagia and fat accumulation, followed by hibernation in response to a difficult period of food scarcity.
- H.T. Jansen, et al., Hibernation induces widespread transcriptional remodeling in metabolic tissues of the grizzly bear, Communications Biology, 2019
- E.L. Arrese and J.L. Soulages, Insect fat body: energy, metabolism, and regulation, The Annual Review of Entomology, 2010
- E.C. Hellgren, Physiology of hibernation in bears, Ursus, 1998
- R. Hissa, et al., Seasonal patterns in the physiology of the European Brown Bear (Ursus-Arctos Arctos) in Finland, Comparative Biochemistry and Physiology Part A: Physiology, 1994
Fat storage syndrome versus metabolic syndrome
Professor Johnson found that during that process, the animals develop all the characteristics of metabolic syndrome known in humans.
Metabolic syndrome in humans can now be considered an epidemic with several frightening characteristics, such as:
- An increased percentage of fat around the organs (also known as visceral fat)
- Insulin resistance
- A fatty liver
- An increased level of triglycerides (fat)
According to Professor Johnson, this is a normal, natural process, not a disease.
Therefore, he suggests that this phenomenon should be called fat storage syndrome instead of metabolic syndrome.
Survival of the fattest in the animal kingdom
The famous quote “Survival of the fittest” belongs to the British Charles Darwin‘s theory of evolution and the process of natural selection in nature. In other words, only the species with the greatest adaptability can survive.
According to Professor Johnson, this statement also applies to fructose and fat storage. Hence, he jokingly turned it into “Survival of the fattest.”
The reason for this is apparent. In nature, many animals only survive winter if they get fat enough during autumn.
An animal with a lean body without much fat reserve would not survive a harsh winter.
Fat storage in animals in preparation for winter months
You could say that animals use a kind of fat switch for their survival.
In preparation for the winter months, they fatten up in the fall, then burn the extra stored fat when it gets cold during winter and food is scarce.
In practice, this is an excellent survival system that has proven its worth for centuries.
Fructose increases body fat storage
Humans also have such a built-in fat storage system. Except that with us, this system is considered a kind of disease…
The signal for fat storage in the human body is given by fructose (also in animals, by the way).
Like animals, we as humans are very sensitive to the substance fructose.
Evolutionary adaptations are the cause
Professor Johnson believes that the reason lies in evolutionary adaptations during the Miocene era.
He presents evidence for this in his scientific study Redefining Metabolic Syndrome as a Fat Storage Condition Based on Studies of Comparative Physiology (see link above).
That evolutionary adaptation occurred about 15 million years ago. It resulted in humans and certain monkey species being the only living species to lack the substance uricase.
The lack of this substance uricase in the body, an enzyme that breaks down uric acid, means that the body has to deal with higher uric acid levels. Uric acid stimulates the storage of fat in our bodies.
This mutation (no uricase in our bodies and higher uric acid levels) allowed the affected species (including humans today) to store fat better than ever and survive harsh times.
Overweight and obesity are major threats
This fat storage functionality has saved us since it allowed our forefathers to survive and evolve into the human species we are today.
However, we must now begin to pay close attention so that it does not become fatal to us.
Both humans and animals have a built-in fat switch that can signal the body to store fat.
In humans, that fat storage process occurs in our cells’ power plants when we consume isolated fructose (see Redefining Metabolic Syndrome as a Fat Storage Condition Based on Studies of Comparative Physiology via link above).
Isolated fructose is artificially separated from the fruit for use in the food industry.
Isolated fructose causes permanent fat storage
When we consume isolated fructose through our diet, our body gets the signal to store fat.
Put another way, the same physical principle takes effect as in animals preparing for winter.
Consequently, consuming isolated fructose has a fattening effect on us.
The big problem these days is that isolated fructose and sugar are everywhere. So our body’s fat storage functionality is constantly triggered and stimulated!
As such, the human body is increasingly in a continuous state of fat storage due to constant exposure to isolated fructose.
How exactly does the fat storage system work in humans?
Intake of fructose puts the enzyme fructokinase into action in our body.
That enzyme then consumes much of the energy in our cells, producing uric acid.
Elevated concentrations of uric acid prompt our bodies to store fat.
And the more sugar we eat (in the form of isolated fructose), the better our bodies become at absorbing it.
In other words, over time, our fat storage system becomes permanently active.
But unfortunately, there is no winter when we eat nothing and use up all our fat reserves. As a result, our fat reserves do not get used up during winter.
Serious health consequences from overconsumption of sugar
Fattening up for hibernation was an excellent system for early man and continues to be for animals.
But for modern man, the enormous supply of sugar in our society has created a negative spiral.
Excessive sugar consumption leads to cardiovascular disease, cancer, arthritis, high blood pressure, diabetes, kidney stones, metabolic syndrome, and cancer.
- E. Russo, et al., Fructose and Uric Acid: Major Mediators of Cardiovascular Disease Risk Starting at Pediatric Age, International Journal of Molecular Sciences, 2020
- M.A. Lanaspa, et al., Uric Acid Stimulates Fructokinase and Accelerates Fructose Metabolism in the Development of Fatty Liver, PLOS ONE, 2012
- T. Nakagawa, et al., A causal role for uric acid in fructose-induced metabolic syndrome, The American Journal of Physiology-Renal Physiology, 2006
Evolution increased uric acid and introduced a new taste
To complement his book The Fat Switch, Professor Johnson published additional research in 2013 called Umami: The Taste That Drives Purine Intake.
This study provides more context to his book, making the concept easier to understand.
More specifically, this research describes that the primal adaptation in the human body that caused us to produce more uric acid also led to another adaptation in our mouths.
A new taste in the mouth
A new “savory” taste (called umami) developed in our mouths, making us appreciate certain foods and flavors.
The food tasted via this new taste receptor increased our uric acid levels, causing us to store more fat, gain weight, and survive the cold during winter.
This taste receptor, known as umami, complements the four other basic tastes: sweet, sour, bitter, and salt.
It is no coincidence that this new taste receptor in our mouths sounds Japanese.
A fifth flavor discovered in Japan
This fifth taste (umami) was discovered in 1907 by Japanese professor Kikunae Ikeda of the University of Tokyo.
He made his discovery by isolating the active ingredient of seaweed, glutamate.
Its chemical variant is MSG or monosodium glutamate, also known as vetsin.
Professor Ikeda explained the taste of umami by saying what it was not: not sweet, not salty, not sour, and not bitter. And so he called it the fifth flavor. This was long disputed in academic circles, unjustly, as it turned out later.
What foods and drinks contain umami in natural form?
Umami in beer
A good example is beer, according to Professor Johnson.
He immediately explains that beer is a great way to create lots of uric acid. This is because beer contains not only alcohol but also yeast.
And thanks to those ingredients, beer already scores on the uric acid meter roughly one hundred times higher than whiskey, for example.
Umami in shellfish, spinach, and organ meats
Crustaceans also contain a lot of umami, as do organ meats and spinach.
Beware of umami
Foods with natural umami please our umami taste receptors in the mouth and increase the concentration of uric acid in our bodies.
In turn, this stimulates fat storage in our bodies.
Because of this fat storage effect, we are more at risk of being overweight and obese. Hence, it is better to be careful with these types of drinks and foods, even though they sometimes have numerous good qualities.
Good to know: When uric acid crystallizes in a joint, rheumatoid inflammation can develop. This is better known as gout and can be enormously painful.