Fat is your most dangerous organ. Yes, it is an organ. Although it’s often mistakenly described as a sign of laziness or gluttony, fat is also essential for your health. It controls and directs the most crucial processes in your body. But when you have too much fat, it begins to disrupt your metabolism and becomes one of the deadliest things that can happen to your body.
Today, there are more people with obesity than people who are starving, which is itself a tremendous victory. There are all sorts of ideas about the cause of the obesity epidemic, but it really comes down to one thing: for millions of years, people had to work extremely hard to get food and often faced hunger. Our bodies evolved to hold onto every bit of energy.
The 5 Key Takeaways
- Discover why fat isn’t just storage, but one of the most influential organs in your body.
- Not all fat is the same; there’s a specific type that poses a creeping threat to your health.
- Your fat tissue constantly sends signals to your brain, but what happens when that communication breaks down?
- Excess fat can put your immune system in a constant state of alert, with devastating consequences.
- The serious damage that excess fat causes is fortunately not always permanent and can be reversed.
The temptation of modern food
We’ve made food incredibly delicious and ultra-processed, packed with unhealthy fats, salt, and sugar. Our brains love this, making eating extremely difficult to resist, to the point of addiction. It’s also incredibly convenient, cheap, and provides a lot of energy for little volume, making it not very filling. This leads most of us to regularly overeat without realizing it. Additionally, food is aggressively promoted, especially targeting children.
Fat comes with a lot of shame and blame, which is quite unfair in a world full of temptations that feel good and are available within minutes. Body fat is also often wrongly seen as the culprit, but it’s crucial for your health. If you don’t have enough of it, you can develop problems ranging from infertility to a weak immune system, fatigue, mental health issues, and bone loss. Yet this doesn’t change how bad excess fat is for us. So how does our fat organ become so destructive and what can we do about it?
The true nature of fat
When you take in more energy than you burn, you store it as triglycerides, a kind of organic battery full of energy. This is collected in a large fat droplet inside a white fat cell. When you gain weight, the white fat cells expand with fat; when you lose weight, they shrink again. Only in recent decades have we discovered fat’s most important role: it’s crucial for your health.
Fat is an endocrine organ, part of the system that creates and regulates your hormones. Hormones are chemical signals to your brain, liver, muscles, digestive system, and immune system, ensuring everything works together properly. Unfortunately, when you develop overweight or obesity, your fat organ and the many hormones it releases go completely haywire.
Pros and cons of body fat
Benefits (at a healthy amount)
- It’s essential for the production and regulation of important hormones.
- It serves as a crucial energy storage reservoir for the body.
- It provides insulation against cold and protects your organs like a soft cushion.
- A healthy amount supports the immune system and fertility.
Cons (at an excessive amount)
- It causes chronic inflammation throughout the body.
- It leads to insulin resistance, which can result in type 2 diabetes.
- It significantly increases the risk of heart attacks, strokes, and various types of cancer.
- It disrupts hormone balance, leading to various health problems.
The two types of fat
In adults, fat comes in two types of white fat deposits. The largest portion is subcutaneous fat, the soft, spongy substance under your skin that insulates against cold and serves as energy storage. The other type is visceral fat, which sits between your organs and forms a soft cushion for your delicate internal organs. But this is also the more dangerous type.
These fat cells are super-sensitive to hormones released during stress, like cortisol or adrenaline. When they catch a wave of stress, they release fatty acids directly into your blood. These are then taken up by your liver as a quick source of energy. Additionally, your visceral fat is metabolically very active and is in constant hormonal dialogue with the rest of your body. This is also why the health of two people with the same weight and the same amount of fat can be completely different. If you have a pear-shaped figure and your fat is mainly on your hips or limbs, you run much less risk than someone with an apple-shaped figure, who carries a lot of fat around the torso.
A vicious cycle of damage
As you gain weight in an unhealthy way, this excess visceral fat causes a whole cascade of negative changes in your body. Fat cells swell to their limit until the blood supply is no longer sufficient and they become oxygen-deprived. They become severely stressed or even die.
This is disastrous. If you have overweight or obesity, your fat is essentially a wounded organ that leaks stress and toxins into your system. Especially your visceral fat, which is extra-triggered by stress hormones, makes your blood fatter. This ‘overfeds’ your organs, such as your liver or muscles, which can’t keep up and start to sustain damage. The stress in the cells and the dead fat cells are distress signals that call on your immune system to take action.
The immune system sounds the alarm
Armies of macrophages invade your fat tissue and form clusters. They try to eliminate the source of stress, but can’t. So they stay and call for more help. In the fat of a lean person, about 5% of the cells are immune cells. In someone with obesity, this can be as high as 40%! Active immune cells cause inflammation, making your tissue swell and triggering even more alarm signals.
This is fine for a short period when you’re sick. But when it becomes chronic, it’s like your entire body is under fire from your own system. The inflammatory molecules and fatty acids cause countless tiny wounds on the inside of your blood vessels. This leads to the formation of plaques that desperately try to seal these wounds. This narrows your blood vessels and reduces the flow of oxygen-rich blood. Inflammation also causes your blood pressure to rise, making your heart work harder and dramatically increasing your risk of a heart attack or stroke.
Glossary
- Visceral Fat: The type of fat that accumulates around organs in the abdominal cavity and is considered more dangerous than subcutaneous fat.
- Endocrine Organ: An organ that produces hormones and releases them directly into the bloodstream to regulate processes elsewhere in the body.
- Leptin: Also called the ‘satiety hormone’; it signals to the brain that enough energy is stored and that appetite can be suppressed.
- Insulin Resistance: A condition in which the body’s cells become less sensitive to the hormone insulin, causing glucose to be taken up from the blood less effectively.
Disrupted hormone balance
To make matters worse, the production of hormones by your fat organ becomes completely imbalanced. Take leptin, for example, the hormone that creates a feeling of fullness. With a healthy amount of fat, leptin tells your brain when you’ve stored enough energy so you can eat less and burn more energy. But when you have too much fat, your brain becomes resistant to the constant stream of leptin instead of making you less hungry.
This wrecks your internal food thermostat. This is one reason why many overweight people experience intense hunger. Their fat essentially screams to their brain that they have enough, but the brain no longer hears the message. Your sex hormones also become imbalanced: testosterone is lowered while too much estrogen is produced. In women, this significantly increases the risk of breast cancer.
Most people aren’t aware of how much cancer risk increases from excess fat. In the United States, nearly 10% of all cancer cases are directly related to overweight or obesity. And to make matters worse, cancer patients who also have obesity have much worse outlooks; they succumb to the disease more often and faster.
When hormone balance collapses
All of this is bad enough, but what happens to one of your most important hormones, insulin, is even worse. Insulin is a hormone produced by your pancreas. It signals your cells to open their ‘mouths’ and take glucose from your blood. It’s your body’s way of saying, “Time to eat!”
Due to the constant stream of stress signals from your excess fat, cells throughout your body become resistant to insulin. They become worse at taking up glucose and energy. Your body tries to compensate by producing more insulin and thus ‘screaming’ harder. This can go unnoticed for years and develop into prediabetes, with no or only vague symptoms like fatigue or hunger.
The consequences of type 2 diabetes
But as damage accumulates, your body eventually can’t keep up anymore. Something breaks and you develop type 2 diabetes. The cells responsible for producing insulin become so overwhelmed that they stop functioning properly and eventually give up. Your insulin level plummets and your body can no longer compensate. Meanwhile, your blood is saturated with glucose, yet you feel ravenous, exhausted, and sick.
Imagine trillions of tiny, sharp shards floating through your body, damaging your blood vessels, nerves, and organs, causing slow but constant damage everywhere. At this point, your body is so chronically inflamed that almost all your organ systems are affected. Your kidneys become overwhelmed, causing you to urinate much more frequently. Your vision becomes blurry, your immune system is severely weakened, and wounds heal more slowly. Dying nerves lead to numbness and pain.
Why fat is an organ
Fat tissue was previously viewed primarily as a passive energy storage facility. However, scientific research has shown that fat tissue is much more active and meets the criteria of an organ:
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Active role: Fat tissue is constantly releasing and storing energy to fuel the body.
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Hormone production: It’s one of the largest endocrine organs in the body. It produces and regulates various hormones that influence appetite (leptin), metabolism, blood pressure, immune function, and even mood.
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Communication: Fat tissue constantly communicates with other organs like the brain, liver, and muscles to regulate the body’s energy balance.
A creeping threat
You can experience shortness of breath, chest discomfort, erectile dysfunction, and high blood pressure. Memory problems, difficulty concentrating, mood changes, and even depression can also develop. Your risk of developing virtually any possible deadly disease skyrockets. On average, type 2 diabetes shortens your life by 10 years (16 km) and dramatically reduces your healthy life years, comparable to the effects of smoking.
If current obesity trends continue, by 2050, up to 1 in 3 Americans will have diabetes. There’s no nice way to say this: excess fat burdens almost every organ system in your body, ages you much faster, and often leads to damage and dysfunction in multiple systems at once. Yet fat is still discussed primarily from an aesthetic perspective, with health taking a backseat.
The path back to health
That’s actually astounding when you consider that most, if not all, of the toxic effects of your excess fat disappear as soon as you lose weight and start eating a reasonably healthy diet. Once your fat cells shrink again, the stress stops and your immune system calms down. The excess fat and sugar in your blood drop to normal levels and your body recovers. Even if you already have type 2 diabetes, losing weight can reverse many of the negative effects and dramatically improve your health and lifespan.
So if you’ve been waiting for a nudge to get started, this is it. Nourishing your body with nutritious food keeps it healthy.
Verified Sources
- Dutch Heart Foundation – Explanation of visceral fat and waist circumference as a health indicator
- FIT.nl –and explanation of healthy body fat percentage and measurements
- InBody Netherlands – What is visceral fat and why it matters
- WHO – Facts about overweight/obesity and health risks worldwide
- Harvard Health – Background and risks of abdominal/visceral fat
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Frequently Asked Questions
What is a healthy body fat percentage?
A healthy body fat percentage varies by age and gender; guidelines show that too much or too little fat poses health risks. Use body fat percentage charts as a reference and combine this with waist circumference or waist-to-height ratio for context.
What is visceral fat?
Visceral fat is the deeper abdominal fat that surrounds organs. An excess disrupts hormones and increases cardiometabolic risks, even if your total weight seems normal.
Is a body fat percentage that’s too low unhealthy?
Yes. Too little fat can cause hormone imbalances, reduced immunity, and in women, menstrual irregularities. Therefore, aim for functional, not minimal, fat levels.
Which sports are best suited to reducing body fat?
Combine regular cardio (such as cycling, running, swimming) with strength training to maintain muscle mass and increase resting metabolic rate. Consistency is more important than a “perfect” workout.
How do you measure your body fat percentage?
At home, you can use a skinfold caliper or BIA scale; more accurate options are DEXA, ADP (BodPod), or underwater weighing. Measure at fixed times and compare trends, not individual measurements.
