Obesity is generally viewed as a problem of excess weight, but its effects reach far beyond the number on a scale. The condition can affect hormones, the immune system, and virtually every organ in the body, contributing to a range of chronic and potentially life-threatening diseases.
At the center of many of these changes is inflammation. According to Randa Abdelmasih, MD, DipABOM, an endocrinologist and obesity medicine specialist in the Department of Internal Medicine at The University of Texas Medical Branch (UTMB Health), low-grade inflammation can initially help protect the body. However, when it persists over time, it can contribute to significant health problems throughout the body.
How obesity triggers inflammation
Fat tissue is more than a place where the body stores excess energy. It is an active endocrine organ that releases hormones and other signaling molecules involved in appetite, metabolism, immune function, and inflammation.
As fat cells expand, they can place the body under stress.
“The question I’m often asked is, how are inflammation and obesity related? Fat cells expand and become metabolically stressed, triggering a chronic inflammatory response,” Abdelmasih said. “Inflammation is the body’s natural response to injury or infection. As fat tissue expands, immune cells accumulate within the tissue and contribute to a chronic, low-grade state of inflammation.”
Normally, inflammation subsides once an injury or infection has healed. With obesity, however, the inflammatory response can persist.
“Inflammation on its own is not a problem. In the case of an injury or infection, the body will heal after a period of time,” she explained. “With obesity, the inflammation doesn’t turn itself off. The body continues to think there’s an ongoing problem, and if it goes on for years, inflammatory cells can damage blood vessels, the liver, the pancreas, and other organs.”
Over time, this persistent inflammation can interfere with the normal function of multiple organs and contribute to chronic disease.
Inflammation and Type 2 diabetes
One example is the connection between obesity and Type 2 diabetes. Inflammatory signals interfere with insulin signaling, leading to insulin resistance.
“The cells are inflamed, insulin doesn’t enter the cells as it should, and the pancreas tries to compensate by producing more insulin, but it can’t keep up,” Abdelmasih said.
Eventually, the pancreas can no longer produce enough insulin to overcome insulin resistance. Blood sugar rises, and Type 2 diabetes can develop.
A widespread effect on the body
The same inflammatory processes can affect the cardiovascular system.
Obesity is associated with an increased risk of heart disease and stroke, and Abdelmasih said inflammation is an important part of that connection.
“The organs are damaged, as is the lining of the blood vessels,” she said. “This damage contributes to plaque buildup, which can increase the risk of blood clots, strokes, and hypertension. These conditions are associated with chronic inflammation and can lead to serious health problems over time.”
Inflammation also can affect the body’s ability to regulate abnormal cell growth.
When cancer develops, Abdelmasih said chronic inflammation is often already present, and obesity can contribute to that inflammatory environment.
“Chronic inflammation creates an environment that can promote abnormal cell growth and reduce the body's ability to eliminate damaged cells, increasing the risk of several obesity-related cancers,” she explained. “These inflammatory markers are supposed to protect us, but over the long term, they can turn against us.”
Health is more than a number on the scale
Because obesity affects people differently, Abdelmasih said there is no single weight or body size that determines when someone needs medical care.
“Health exists on a spectrum,” she said. “You might have complications today, but perhaps not. We don’t focus on the scale. We evaluate overall metabolic health and risk factors, such as genetics, family history, and other comorbidities. When does a patient need help? The answer to this is completely individual.”
Inflammation can develop gradually, often without obvious symptoms.
“You might not know anything about it for years, but the problem is there, slowly affecting blood vessels and the lining of organs,” she said.
The good news is that meaningful health benefits can occur even before a person reaches a long-term goal weight.
“You do not need to see dramatic weight loss to see a reduction in inflammation,” Abdelmasih said. “If you weigh 200 pounds and you lose 10, you are already seeing benefits.”
Reducing inflammation can improve health
As weight decreases, inflammatory markers can also decline.
“We have the data showing that obesity-related inflammation and many chronic conditions can improve,” she said. “It’s good to have a goal weight, but it's also important to think of your long-term health. If you are 300 pounds and lose 30, the data shows you have already reversed some of the inflammation. Disease rates begin to drop dramatically.”
With weight loss and regular physical activity, the body can undergo additional changes that improve metabolic health. Inflammatory fat tissue can shrink, and healthier fat tissue may replace some visceral fat, the type of fat stored around internal organs.
The effects of obesity-related inflammation also extend to the brain.
Inflammation and brain health
Abdelmasih said obesity is associated with an increased risk of Alzheimer’s disease, and inflammation may be one factor contributing to that risk.
“The same inflammatory chemicals released by fat tissue that contribute to insulin resistance and affect blood vessels throughout the body may also affect the brain,” she said. “Growing evidence suggests that chronic inflammation and vascular injury may increase the risk of cognitive decline and Alzheimer's disease, although the relationship is complex and continues to be studied.”
Treating obesity without stigma
Because obesity is a complex chronic disease influenced by multiple biological, genetic and environmental factors, Abdelmasih said people should not be stigmatized for struggling with their weight.
“It’s a chronic disease, and there is no shame in asking for help,” she said. “This is a medical condition, not a personal failure. The earlier it’s addressed, the better the opportunity to reduce inflammation before it does too much damage. It’s much better to prevent or reduce inflammation rather than wait until a chronic disease develops, and we can offer help and support for that.”