At one time, we thought the main purpose of fat was to serve as a storage depot for energy. In other words, you carried around excess fat as a reserve fuel source you could tap into during times of need. But more recent research shows fat tissue is active, producing a variety of hormone-like factors that impact the way your body functions and have the ability to fuel inflammation.
How Are Obesity and Inflammation Linked?
One theory linking obesity and inflammation goes like this. When fat cells expand and become larger, blood flow to them is reduced. This reduction in blood flow activates genes involved in inflammation. As a result, fat cells produce more inflammatory chemicals called cytokines that turn on inflammation. The resulting inflammatory response is linked with another common problem obese people obese experience – insulin resistance.
What is insulin resistance? It’s where cells become less sensitive to the effects of insulin produced by your pancreas. As a result, the pancreas has to produce more, leading to high circulating levels of insulin. It’s a vicious circle that further fuels obesity. That’s because high levels of circulating insulin block fat breakdown and promote fat storage. Not to mention insulin resistance appears to be an underlying factor in the development of type 2 diabetes and heart disease.
Acute versus Chronic Inflammation
Inflammation isn’t always a bad thing. In fact, it’s how your body protects itself from foreign invaders and injury. For example, if you cut your hand, blood vessels dilate, chemicals are released and immune cells are recruited to help “clean up the scene of the crime.” These immune cells ingest debris, dead tissue and bacteria to protect the area and allow it to heal. Acute inflammation is a protective response. This acute inflammatory response is short-lived and can be activated in response to injury or infection. With acute inflammation, you experience obvious signs and symptoms like redness, swelling, heat, and pain.
In contrast, chronic, low-grade inflammation may smolder and linger for years, silently damaging tissues. If not controlled, acute inflammation can turn into chronic inflammation. There’s also growing evidence that factors like eating a poor diet, stress, cigarette smoking, exposure to toxins, too little or too much exercise and obesity can trigger a chronic inflammatory state in the absence of acute inflammation. In terms of diet, processed foods and a diet with a high ratio of omega-6 to omega-3 fatty acids are pro-inflammatory whereas a diet rich in fruits, vegetables, antioxidant spices, and omega-3 fatty acids helps to keep inflammation in check.
Why is chronic inflammation such a bad thing? Research suggests that chronic inflammation may be a factor in a number of chronic problems including heart disease, type 2 diabetes, cancer, autoimmune diseases, and Alzheimer’s disease. Obesity is linked with an increased incidence of these diseases and obesity-induced inflammation may be a reason why.
How Do We Know That Obesity Fuels Inflammation?
In one study, researchers found higher levels of a protein called AIF-1 in obese women compared to women of normal weight. This is an inflammatory protein that’s normally activated during times of injury. Interestingly, this protein is also linked to insulin resistance. Another study published in the journal JAMA showed another inflammatory protein called C-reactive protein or CRP tends to be higher in those who are obese. Higher levels of CRP are also linked with a greater risk for heart disease.
Obesity and Inflammation: The Bottom Line?
Fat cells release inflammatory chemicals called cytokines that fuel inflammation. In turn, inflammation causes tissue damage that may increase the risk for chronic health problems including autoimmune diseases, heart disease, type 2 diabetes, cancer, and Alzheimer’s disease. This may be one way that obesity increases the risk of health problems. The good news? Research shows losing those extra pounds of body fat reduces markers for inflammation and improves health in other ways as well.
References:
Diabetes February 2009 vol. 58 no. 2 307-308.
Gastroenterology. Volume 132, Issue 6, Pages 2169-2180, May 2007.
Medical News Today. “Inflammation protein linked to obesity in women”
JAMA. 1999 Dec 8;282(22):2131-5.
Clin Sci (Lond). 2004 Oct;107(4):365-9.
Nutr Res Rev. 2008 Dec;21(2):117-33. doi: 10.1017/S0954422408138732.
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