By Dr. Asnat Raziel, bariatric surgeon specializing in obesity treatment, metabolic health and healthy longevity; Director of the Multidisciplinary Center for Obesity Treatment, Assia Medical, Assuta Ramat HaChayal, Tel Aviv
Obesity and inflammation: what is the connection?
Obesity and inflammation go hand in hand, yet most people are unaware of it. When we think of inflammation, we usually picture redness, heat or pain. In obesity, however, it is a different process: a quiet, persistent, low-grade inflammation with no symptoms. Precisely because it is so silent, it damages the blood vessels, the liver and the body’s blood sugar control over many years.
In this article, I explain how fat tissue generates inflammation, which diseases are linked to it and how to actually bring it down. The good news: weight loss, diet and physical activity lower the markers of inflammation in the blood.
Fat tissue is an active organ
For years, fat tissue was seen as a simple energy store. We now know it is an active organ that secretes hormones and other substances that affect the whole body. As early as 1993, researchers found that the fat tissue of animals with obesity produces TNF-α, an inflammatory substance that interferes with insulin action. When the researchers blocked it, insulin sensitivity improved.
A review from Harvard Medical School describes how research in the field has developed since then. Researchers now view fat, and especially belly fat, as an organ that communicates with other tissues. What’s more, waist circumference predicts risk better than BMI (body mass index) alone.
How inflammation develops in obesity
When fat cells grow very large, their blood supply cannot keep up. Some of the cells become starved of oxygen and even die. In response, the immune system recruits clean-up cells called macrophages into the tissue.
A 2003 study showed that the number of macrophages in fat tissue rises as weight increases, in humans as well. These cells produce almost all of the TNF-α in the tissue, as well as a substantial share of another inflammatory substance called IL-6. The result is a vicious cycle: fat attracts immune cells, and the immune cells drive up inflammation. In the medical literature this is called meta-inflammation, meaning inflammation that originates in metabolism. A good summary of the mechanisms appears in the entry on the pathophysiology of obesity.
Obesity and inflammation in blood tests
The most common marker of general inflammation in the body is CRP (C-reactive protein), a protein the liver produces in response to inflammation. A large American survey examined 16,616 adults. Men with obesity were 2.13 times more likely to have elevated CRP, and women with obesity 6.21 times more likely. The association was also seen in young adults aged 17 to 39.
In addition, a high waist-to-hip ratio went hand in hand with high CRP, regardless of BMI. In other words, where fat is stored matters just as much as how much there is. I have written more about this in my article on visceral fat, the fat that surrounds the internal organs.
Obesity and inflammation: which diseases are linked
Chronic inflammation explains part of the link between obesity and many diseases. First, it contributes to insulin resistance and type 2 diabetes. Second, it contributes to atherosclerosis and heart disease. The CANTOS trial, for example, showed that an anti-inflammatory drug reduced cardiovascular events even without lowering cholesterol. However, it increased the risk of fatal infections, so it is not a routine treatment.
Obesity is also linked to other inflammatory diseases. For example, psoriasis and obesity often occur together. The same is true of inflammatory bowel disease and obesity, including Crohn’s disease. Fatty liver and accelerated aging are also tied to the same silent inflammation. That is partly why there is interest in treatments such as senolytic creams, which aim to target aging cells that release inflammatory substances.
How to lower inflammation: weight loss
The most effective step is weight loss. A review of 33 studies found that every kilogram lost lowered CRP by an average of 0.13 mg/L. The association held both for lifestyle change and after bariatric surgery.
Put simply, even moderate weight loss improves the inflammatory state. By contrast, crash diets that end in weight regain do not help in the long run. The goal is weight loss that lasts.
Obesity and inflammation: diet, exercise and sleep
The Mediterranean diet is the most thoroughly studied eating pattern. A randomized trial in Italy included 180 patients with metabolic syndrome. After two years, those who ate whole grains, vegetables, fruit, nuts and olive oil had lower levels of CRP and IL-6. Their blood vessel function also improved.
On the other hand, ultra-processed food, sugary drinks and excess sugar are linked to higher inflammation. Regular exercise, especially a combination of walking and strength training, also helps. Adequate sleep and cutting down on smoking complete the picture. I have written about combining these habits in my article on a healthy lifestyle and obesity medications.
Drug treatment for obesity and inflammation
When lifestyle change is not enough, drug treatment can help. GLP-1 medications such as semaglutide lower weight and also reduce inflammation markers. In the STEP-HFpEF trial, for example, CRP fell by 43.5% in the semaglutide group, compared with 7.3% in the placebo group.
These drugs also quiet “food noise,” the constant, intrusive thoughts about food. That makes it much easier to stick with a healthy diet. I have written more about their effect on inflammation in my article on GLP-1 drugs and chronic inflammation. In our clinic, we build a plan for each patient that combines diet, physical activity and, when needed, medication.
The bottom line
Obesity and inflammation form a vicious cycle: enlarged fat tissue releases inflammatory substances, and the inflammation raises the risk of diabetes, heart disease and other inflammatory conditions. But this cycle is reversible. Weight loss, a Mediterranean diet, physical activity and good sleep lower inflammation markers, and GLP-1 medications can help when needed.
The information in this article is general and does not replace personal medical advice.
Frequently asked questions
How do I know if I have chronic inflammation?
This kind of inflammation usually causes no noticeable symptoms. A high-sensitivity CRP blood test can point to it, but the result should be interpreted with your doctor.
How much weight do I need to lose to reduce inflammation?
There is no fixed threshold. According to a review of 33 studies, every kilogram lost lowered CRP by an average of 0.13 mg/L.
Is there an anti-inflammatory diet?
The Mediterranean diet has been tested in a randomized trial and lowered inflammation markers in people with metabolic syndrome.
Do GLP-1 medications reduce inflammation?
In studies, they lowered CRP levels. Part of the effect comes from weight loss.
References
Adipose expression of tumor necrosis factor-alpha: direct role in obesity-linked insulin resistance
Obesity is associated with macrophage accumulation in adipose tissue
Elevated C-reactive protein levels in overweight and obese adults
The effect of weight loss on C-reactive protein: a systematic review
Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease
Semaglutide in Patients with Heart Failure with Preserved Ejection Fraction and Obesity
