Fat Is an Immune Organ. That Is Why It Hurts.

Visceral fat is not a storage depot. It is active immune tissue that pumps signaling molecules into the bloodstream all the time. A large share of those signals are inflammatory. These signals lower the threshold at which ordinary tissue signals register as pain, and they keep central sensitization going.

That one fact reorganizes much of what otherwise looks like unrelated illness.

The immune connection is not a metaphor

Fat cells and immune cells share an ancient family line. In Drosophila, the fat body does the work that mammals split between fat tissue (adipose tissue) and the innate immune system. The same organ does both jobs. In humans the split is more a division of labor than a clean break, and adipose tissue kept a great deal of its immune signaling power.

This is why fat tissue releases the molecules it does:

• TNF-α, IL-6, IL-1β — classic pro-inflammatory cytokines (immune signals)
• Leptin — the fullness hormone, which is built like the cytokine family and acts like one
• Adiponectin and resistin — adipokines (fat-made hormones) with opposing metabolic effects

One result deserves emphasis. C-reactive protein, the inflammation marker checked on routine labs, is made by the liver, largely on orders from IL-6 in the blood — and a major source of that IL-6 is fat tissue. When CRP is high in a patient with central adiposity (fat around the middle), much of what is being measured comes from the fat itself.

Leptin resistance travels with insulin resistance

Leptin signals fullness (satiety). When it stays too high for too long, the receptors stop responding as well. Insulin follows the same pattern, and the two usually show up together.

The practical result is a patient with high leptin in the blood who does not feel full. The same patient has high insulin that drives storage rather than release of fat. That is not a willpower state. It is a signaling failure, and it is measurable. We cover the insulin side in hyperinsulinemia and chronic pain.

Why this reaches pain

A raised inflammatory baseline that does not go away lowers the threshold at which ordinary tissue signals register as pain. It slows healing after injury. It keeps central sensitization going. That is the link between a broken metabolism (metabolic dysfunction) and pain that does not settle. It also explains a pattern most chronic pain patients know. The same procedure that helped someone else helps them less, and for less time.

There is a second loop worth naming. Highly palatable processed food drives dopamine release through the brain’s reward pathway. The pattern overlaps with other reinforcing substances. Animal models in which dopamine signaling is disrupted show markedly less overeating of palatable food. That is evidence that the reward pathway, not appetite alone, is doing the driving.

Here is the loop as we see it in the clinic. Reward-driven eating raises body fat. Fat raises inflammation. Inflammation raises pain. And pain increases the pull toward the easiest source of dopamine relief, which for most people is food. We wrote about that overlap in addiction, chronic pain and type 2 diabetes share one substrate.

Where the evidence stands

Two claims often made in this area:

Well established: Fat tissue makes hormones (it is endocrine) and is immune-active. IL-6 from fat tissue drives CRP made in the liver. Leptin and insulin resistance occur together. Central adiposity is strongly associated with metabolic syndrome and the disease that follows from it.

Still debated in mainstream guidelines: whether industrial seed oils are a main driver of the rise in metabolic disease. Our position is not in doubt. In a population that is already metabolically sick, seed oils are harmful.

The timeline in the talk is specific. Industrial seed oil entered the human diet in commercial amounts from around 1917 — against two to three million years of human history without it. The sharp uptake came after the 1977 dietary guidelines. Those guidelines told people to eat less fat and accepted more carbs in its place. Canola oil use followed soon after. Diabetes rates began climbing roughly five to seven years behind it. The proposed mechanism is oxidized linoleic acid.

That correlation is real, and the mechanism is biologically plausible. Refined carbohydrate, total calories, ultra-processing and sitting still rose in the same decades, and they do damage too. That does not clear seed oils. We tell our patients to cut industrial seed oils out. Dr. Gurpreet Singh Padda, MD, MBA, MHP, puts it bluntly: industrial seed oils will one day be viewed with the disdain now reserved for cigarettes.

On prevalence, the same talk puts adverse metabolic syndrome at more than 25% of US adults by formal criteria. Count the metabolic damage a clinician can identify, not just the diagnostic checklist, and the figure is plausibly 60–70%. The gap between those two numbers is the point. The formal criteria are a diagnostic convention, and a great many people are metabolically unwell before they meet them.

Prevalence figures and the seed-oil timeline as presented by Dr. Padda in a professional educational presentation to a clinical audience.

What we actually ask patients to do

On purpose, none of this is calorie counting.

• Shorten the eating window. Fewer eating times means fewer insulin spikes and a lower total insulin load (the area under the insulin curve). That is the target, not the calorie total.
• Stop snacking before worrying about anything else. It is the one change with the largest effect on insulin exposure.
• Eat real food rather than cutting out food groups. When a change feels like deprivation, the pull of whatever was removed reliably gets stronger.
• Eat to about eight parts in ten full — the Okinawan hara hachi bu habit. It changes how you relate to the meal rather than adding another number to track.

We avoid calorie counting for two reasons. First, it is imprecise by nature: your resting energy need varies a lot from day to day, and your gut bacteria (microbiome) change how much you pull from the same meal. Second, it uses up willpower that is better spent on food quality. See treating metabolic disease at the dietary root cause.

Frequently asked questions

I am not overweight. Can I still have this problem?

Yes. Visceral fat is not always visible from the outside, and the inflammatory state can be present in people at normal body weight. It is found with blood markers (biomarkers), not by appearance. See hyperinsulinemia and chronic pain.

Is my elevated CRP coming from my fat?

Often, in part. The liver makes CRP largely in response to IL-6 in the blood, and fat tissue is a major IL-6 source. CRP is non-specific, so it has to be read alongside the rest of the picture.

For how inflammation and diet drive chronic pain, read How Inflammation and Diet Drive Chronic Pain and Hormone Problems.

Are seed oils the cause of all this?

They are not the only cause, but they are a real one. Industrial seed oils are harmful in a population that is already metabolically sick, so we tell our patients to cut them out. Refined carbohydrate and ultra-processed food rose at the same time and do damage too, so we cut those as well. See treating metabolic disease at the dietary root cause.

Why no calorie counting?

Because it is inaccurate in practice. It spends willpower that food quality needs. And it reliably leads to reward eating that cancels the deficit. Shortening the eating window targets insulin exposure more directly.

Where can I be evaluated?

Padda Institute, 4477 Woodson Rd, Suite 100, St. Louis, MO 63134, serving the St. Louis region across Missouri and Illinois. Call (314) 481-5000 or text (314) 886-5902.

The office, hours and directions are on our Locations page.

Key takeaways

• Fat tissue is endocrine and immune-active. It shares a family line with the innate immune system.
• Much of a raised CRP in central adiposity traces back to IL-6 made by fat tissue.
• Leptin resistance and insulin resistance show up together. They are signaling failures, not willpower failures.
• The food-reward loop is supported by animal models, and we see it in the clinic.
• Industrial seed oils are harmful in a metabolically sick population. We tell patients to cut them out.
• The treatment is the eating window and food quality, not calorie math.

This article is educational and is not a substitute for evaluation, diagnosis, or treatment by a physician. Individual results vary. Do not start, stop, or change any medication without consulting your physician.

Medically reviewed by Gurpreet Singh Padda, MD, MBA, MHP — Board Certified in Anesthesiology, Pain Medicine, Interventional Pain Management, Addiction Medicine, and Obesity Medicine. Last reviewed August 2026.

Dr. Gurpreet Singh Padda, MD, MBA, MHP