Obesity: the inflammatory disease nobody treats as such

Obesity spent decades being treated as a problem of discipline or character — someone with more willpower would eat less and move more. The science of the last two decades has dismantled that narrative definitively, but much of the health system has still not changed its approach.

Obesity is, fundamentally, a chronic systemic inflammatory disease. Understanding this mechanism changes everything about how we should diagnose it, treat it and follow it.

What meta-inflammation is

Unlike acute inflammation — the kind that appears after a cut or an infection, with visible signs, and disappears in days — meta-inflammation is a chronic, low-grade, sustained inflammatory state, with no identifiable infectious agent. The term was coined precisely to describe what happens in excess adipose tissue.

Adipose tissue is not a passive energy depot. It is an active endocrine organ that produces adipokines and inflammatory cytokines (such as TNF-α, IL-6 and IL-1β) and recruits macrophages. When in excess — especially visceral adipose tissue — it enters a state of chronic inflammation that spreads systemically. This is the root of practically all the complications associated with obesity.

Clinical consequences

Insulin resistance and type 2 diabetes

Inflammatory cytokines interfere with insulin signaling in peripheral tissues. The result is progressive insulin resistance, compensatory hyperinsulinism and, eventually, type 2 diabetes. The process begins long before measurable hyperglycemia.

Cardiovascular disease

Systemic inflammation feeds atherosclerosis: dysfunctional endothelium, unstable plaques, increased thrombogenesis. Visceral obesity is an independent predictor of cardiovascular events, even in individuals with cholesterol and blood pressure within normal limits.

Cancer

The International Agency for Research on Cancer (IARC), part of the World Health Organization, recognizes sufficient evidence for thirteen types of cancer associated with excess body fat. In Brazil, it is estimated that about 4% of cancer cases are attributable to excess adiposity, positioning obesity among the main modifiable risk factors for neoplasms.

Mental health

The relationship between obesity and depression is bidirectional. Systemic inflammation affects the central nervous system, alters neuroplasticity and is associated with depressive and anxiety conditions. Treating depression without considering the inflammatory component is frequently to underestimate the disease.

Other manifestations

Obstructive sleep apnea, non-alcoholic fatty liver disease (NAFLD/MASLD), polycystic ovary syndrome and accelerated osteoarthritis have the inflammatory component as a relevant mediator.

Why this view is still rarely applied

Most approaches still start from a simplified model: "eats too much, moves too little." Treatment boils down to a restrictive diet and physical-activity guidance — which do have evidence, yes, but are often insufficient when addressed in isolation.

This model fails because it ignores the neuroendocrine mechanisms that regulate weight (leptin, ghrelin, insulin, GLP-1), does not consider that meta-inflammation itself alters the regulation of appetite and energy expenditure, places therapeutic failure entirely on the patient — reinforcing stigma — and underestimates the need for pharmacological treatment in a large share of cases.

The role of GLP-1 agonists

GLP-1 receptor agonists (such as semaglutide and liraglutide) have changed the treatment of obesity. They promote weight loss, with robust evidence, and there are signs of anti-inflammatory effects that may go beyond weight reduction — a hypothesis still under study.

Recent studies show a reduction in systemic inflammatory markers and, in the SELECT trial, in people with established cardiovascular disease and without diabetes, a reduction in major cardiovascular events. Kidney and liver outcomes are still under investigation. The mechanism goes beyond satiety: it is a broad metabolic and inflammatory modulation. This does not mean that all patients need GLP-1 — it means that treatment must be individualized and open to the use of pharmacotherapy when indicated, without the prejudice that "losing weight with medication is not real."

What changes in primary care

Treating obesity as a chronic inflammatory disease implies:

• Complete diagnosis — not just BMI. Assessment of visceral adipose tissue (waist circumference), active screening for complications, inflammatory markers when indicated.
• Multidimensional approach — lifestyle intervention, behavioral support and pharmacotherapy when appropriate, without stigma.
• Realistic goals — a loss of 5 to 10% of body weight already produces a significant reduction in inflammatory markers and cardiovascular risk factors. It is not about the perfect weight.
• Longitudinal follow-up — obesity is chronic and requires long-term follow-up, like any other chronic disease.
• No blaming — the patient who "cannot lose weight" frequently has biological mechanisms working against them. Recognizing this is part of care.

For the patient

If you have a diagnosis of obesity — or suspect one — the conversation with your doctor should not be only about how much you weigh. It should include: what is your cardiovascular risk? Are there signs of insulin resistance? Do you have apnea? Is your mental health stable?

Obesity is not a personal failing. It is a complex disease, with well-described biological bases, that deserves a serious, longitudinal and non-judgmental medical approach. That is what I commit to offering.