Protect against damage caused by excess weight

Obesity is a major threat to longevity and health. In addition to physically burdening the body’s structure, fat cells accelerate disease risk and aging. They do this by churning out enormous amounts of inflammatory factors.1

Quercetin is a bioactive flavonoid found in onions, apples, and other botanical sources.

In an animal study published in 2018, quercetin was shown to prevent obesity, while also offsetting the damaging effects of excess fat tissue.

With more than 2 in 3 adults considered overweight or obese,2 these new results show that quercetin may represent a defense against the age-accelerating consequences of excess fat.


The dangers of excess fat

Obesity imposes grave risks on our health, especially as we age.

It increases the wear and tear on all body systems and raises blood lipid levels.

It also has ongoing effects that are less visible yet are more life-threatening.

When fat cells (adipocytes) and fat storage sites (adipose tissue) increase in size, an environment of insufficient oxygen supply (hypoxia) sets in, leading to cellular and biochemical changes.3

For example, hypoxia alters how fat cells express their genes, with the ultimate development of system-wide inflammation.4

Widespread inflammation is accompanied by metabolic disruptions. These include not only insulin resistance, type II diabetes, and fatty liver disease, but also atherosclerotic changes in blood vessels, heart disease, and stroke.5,6

Inflammatory changes in the brain and bone lead to neurodegenerative disorders and osteoporosis, respectively.7,8 At some point, DNA repair mechanisms and cell replication controls are lost, with a concomitant spike in cancer development.6,9

In short, fat tissue is perhaps the most powerful accelerator of aging.


Quercetin prevents obesity

The first step in protecting against obesity-related health dangers is to prevent diet-induced obesity in the first place.

A study published in early 2018 showed that quercetin could help prevent diet-induced obesity—even in the presence of a high-fat diet.

For the study, rats were fed either a normal diet, a high-fat diet, or a high-fat diet along with a quercetin-rich dietary supplement.10

After 8 weeks, rats in the groups fed high-fat diets gained weight compared with those on a normal diet. However, the quercetin-supplemented rats fed a high-fat diet gained 8.5% less weight by the end of the study, compared with those fed the high-fat diet alone.10

The prevention of weight gain was accompanied by impressive protections against internal fat accumulations. By the end of the study, compared to high-fat diet controls, quercetin-supplemented animals on high-fat diets had:

  • 23% less total body fat,
  • 23.8% lower serum triglyceride levels, and
  • 22% less visceral (abdominal) fat.


Improvements at the cellular level 

These macroscopic improvements in body weight, fat distribution, and lipid profile were accompanied by microscopic changes in the architecture of liver and fat cells.10

Healthy, lean animals have dense, well-organized liver cells lacking any droplets of free fat.

Rats fed a high-fat diet have loose, poorly-organized liver tissue riddled with droplets of free fat that won’t stay in cells.

Lean animals have compact, small fat cells, while rats fed a high-fat diet have enlarged, overfilled fat cells.10

These changes in the structure of the cell negatively impact health because a liver loaded with fat cells (fatty liver) is a highly inflammatory environment.11 This situation may lead to poor liver function, declining insulin sensitivity, and eventually to liver damage leading to cirrhosis, fibrosis, and liver failure.

Large, unhealthy fat cells elsewhere in the body only add to the inflammatory burden12—which adds to the risks of inflammation-driven diseases like heart attacks, strokes, cancer, and even osteoporosis.

This study found that when rats fed a high-fat diet were also fed a quercetin-rich supplement, the architecture of their liver and fat cells changed to closely resemble those of lean animals fed a normal diet, with few liver oil droplets and small, orderly fat cells.10

Overall, this study shows that quercetin helps reduce diet-induced weight gain while also protecting tissues from excessive, destructive fat inflammation.

But what we learn from this study is only a portion of the story. Still more exciting is the emerging picture of what quercetin can do to existing fat stores—activity that amounts to a detoxification of fat tissue.

The result is the promotion of health and deceleration of aging.


Quercetin’s multi-targeted effects

Two animal studies published in the past several years have demonstrated that supplementing with quercetin contributes to significant reductions in body weight—while also protecting against the dangerous impact of diet-induced accumulation of fat.13,14

Together, these studies offer a comprehensive picture of quercetin’s ability to attack obesity on multiple levels.

Here are the four primary ways quercetin accomplishes these feats.


Quercetin reduces fat-generated inflammation

Animal studies show that supplementation with quercetin (when given in combination with resveratrol) works in two key ways to reduce obesity-induced inflammation.

First, quercetin precisely controls the genetic expression of pro-inflammatory signaling molecules (cytokines). In addition, this nutrient combination has been shown to produce significant reductions in the size of body-fat stores, to lower body weight, result in smaller fat- cell sizes, and reduce blood lipid levels.15

An even more striking finding is quercetin’s effect on the hypothalamus, the body’s central metabolic regulatory center.16

Obesity can activate the immune cells of the central nervous system, called microglia, producing destructive, localized inflammation, including in the hypothalamus. Inflammation in the hypothalamus has far-reaching consequences because of its intimate involvement in everything from core body temperature to basal metabolic rate to appetite and activity.

By activating microglia, obesity has been implicated in upsetting the ways the body manages its energy balance, as well as in metabolic complications like diabetes, and in neurodegenerative diseases.17-22

A recent animal study found that quercetin can reduce obesity-induced inflammation in the hypothalamus of obese mice. It accomplishes this by inducing an enzyme that protects brain tissues against oxidative stress that drives inflammation.16

By reducing fat-generated inflammation, quercetin combats a potent age-accelerator.15,23


Quercetin upregulates AMPK

AMPK is one of the body’s central metabolic regulatory signaling enzymes and is found in every living cell. It is considered one of the body’s most powerful anti-aging tools.

When activated, AMPK enhances rates of energy extraction by burning fat, and accelerating cleanup of toxic debris that accumulates inside aging cells (autophagy).

Quercetin has been shown to activate AMPK.14,15 Doing so promotes a more youthful cell type in terms of activity and vulnerability to stress of all kinds.24-26

A study of rats fed a high-fat diet (which induced obesity) showed that quercetin stopped fat-induced suppression of AMPK. This freed the animals’ cells to revert to more youthful activity, while also reducing many inflammatory processes.15


Quercetin promotes a healthy gut microbiome

The gut microbiome is the community of millions of microorganisms that live in the intestinal tract. Obesity contributes to an imbalanced microbiome (called dysbiosis), a problem that is closely related to a wide range of human health issues, including diabetes and cardiovascular disease.27-29

Research suggests that obesity-related dysbiosis may produce “leaky gut,”30 a condition that allows bacterial toxins to enter the bloodstream while promoting liver damage and excessive inflammation.

In a mouse study, treatment with quercetin restored balance to the gut microbiome and turned off dysbiosis-related inflammatory and stress responses.31

One dramatic consequence of this effect of quercetin is a reduction in the severity of obesity-induced, non-alcoholic fatty liver disease (NAFLD).31

NAFLD is a serious consequence of insulin resistance and can lead to non-alcoholic steatohepatitis, which is a precursor of liver cirrhosis and even liver cancer.32

Supplementing with quercetin achieves these gut-microbiome-related results by interacting with the many species that make up the gut microbiome. It stops the growth of bacteria that have pro-inflammatory and other harmful properties, while promoting the growth of bacteria known to protect the gut by producing mucous and anti-inflammatory compounds.23,33

In short, quercetin harnesses gut bacteria as allies in the fight against total-body impacts of obesity.


Quercetin converts white fat to brown fat

The bulk of fat tissue in adults is composed of white adipose tissue, or simply “white fat.”

This type of fat is what provides our energy supply between meals.34 Unfortunately, it is also the source of inflammation and other harmful metabolic changes associated with excessive fat stores.11,27

But infants (and many small mammals) have fat deposits that are made up of brown adipose tissue, or simply “brown fat.” Unlike the white variety, brown fat has the capability of converting energy stored as fat into heat.35,36

Research shows that mice with increased numbers of brown fat cells are lean and protected from obesity, compared with those dominated by white fat.37

We’re now learning that it’s possible to boost brown-fat-cell content in human adults by triggering the cellular switch from white to brown.34-41 The result is the conversion of stored fat into fat that is burned for energy and readily shed from the body.

It’s a discovery that is revolutionizing our approach to obesity—and quercetin could play a major role.

Animal studies have now demonstrated that quercetin—either alone or in combination with resveratrol—can convert white fat cells into those resembling brown fat cells.40,42,43

This “browning” process is a promising strategy for mitigating the impact of obesity.42

As an added benefit, quercetin-induced fat-browning increases the activity of PPAR-alpha, a gene regulator that promotes the expression of genes involved in burning fat and glucose.40



Obesity is a major threat to human health and longevity.

Excessive amounts of certain types of fat tissue generate inflammation that accelerates the aging process and leads to insulin resistance, diabetes, heart disease, cancer, osteoporosis, and even neurodegenerative disorders.

Quercetin has been shown to help protect against obesity itself, as well as its age-accelerating consequences.



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