Inflammation rises when your immune system detects threats, but it also climbs in response to everyday factors you can control: what you eat, how much you move, how well you sleep, and how much stress you carry. Chronic, low-grade inflammation is different from the acute kind that helps heal a cut or fight an infection. It simmers quietly, driven by diet, body composition, gut health, and environmental exposures, and over time it contributes to heart disease, diabetes, and other serious conditions.
Refined Sugar and High-Fructose Foods
High sugar intake is one of the most well-documented dietary drivers of inflammation. Fructose, whether from table sugar or high-fructose corn syrup, can only be processed by the liver. Unlike glucose, there’s no feedback mechanism to slow down fructose metabolism when the liver gets overloaded. The excess gets converted into fatty acids, and those fatty acid byproducts trigger inflammatory processes and the formation of damaging free radicals.
Over time, this fat buildup in the liver can progress from simple fatty liver disease to an actively inflamed state. Tissue biopsies show a gradual increase in systemic inflammatory markers, including CRP and IL-6, as liver health worsens along that spectrum. Fructose also promotes the growth of visceral fat, the deep abdominal fat that actively pumps out inflammatory signaling molecules.
There’s another pathway too. Animal studies suggest fructose encourages bacterial overgrowth in the gut and weakens the intestinal lining. When bacterial toxins slip through into the bloodstream, they activate immune receptors in the liver that release a cascade of inflammatory signals. Even beyond fructose specifically, foods with a high glycemic index cause repeated blood sugar spikes that generate free radicals and provoke inflammatory cytokine release in the hours after eating.
Trans Fats and Omega-6 Imbalance
Trans fats, found in partially hydrogenated oils and some processed foods, activate a key inflammatory switch inside cells called NF-κB. This master signaling pathway ramps up production of inflammatory cytokines and damages the lining of blood vessels. Population studies in American adults have found that circulating trans fat levels correlate with higher levels of CRP, the liver protein most commonly used to measure systemic inflammation.
The balance between omega-6 and omega-3 fatty acids in your diet also matters. Omega-6 fats, abundant in soybean oil, corn oil, and many processed foods, get converted into compounds that promote inflammation and allergic responses, including certain prostaglandins and leukotrienes that recruit immune cells to tissues. Omega-3 fats from fish, flaxseed, and walnuts do the opposite: they block the enzymes that break omega-6 into those pro-inflammatory compounds, while simultaneously boosting anti-inflammatory molecules. When omega-3 intake is low, the inflammatory side of that equation wins, and the body overproduces the signaling molecules that drive swelling, pain, and immune activation.
Excess Body Fat
Fat tissue isn’t a passive storage depot. It’s an active endocrine organ that releases a steady stream of inflammatory molecules, including TNF-α, IL-6, and leptin. Visceral fat, the kind that surrounds your organs, is especially problematic. A study of patients undergoing bariatric surgery found that IL-6 levels in the blood draining from visceral fat were about 50% higher than in the rest of the circulation. That portal vein IL-6 level correlated directly with whole-body CRP, confirming visceral fat as a direct source of systemic inflammation.
IL-6 from fat tissue travels to the liver and stimulates it to produce CRP and fibrinogen, both markers of an active inflammatory state. It also triggers the release of white blood cells and platelets from bone marrow and activates the lining of blood vessels, setting the stage for plaque formation. This is a large part of why carrying excess abdominal weight raises the risk of heart attacks and strokes independently of other factors like cholesterol.
Chronic Stress
Short-term stress triggers a cortisol spike that normally keeps inflammation in check. Chronic stress does something counterintuitive: it makes your tissues stop responding to cortisol. This phenomenon, called glucocorticoid receptor resistance, means the hormone is still circulating but your immune cells no longer obey its “stand down” signal.
Research published in the Proceedings of the National Academy of Sciences tested this directly. People who had experienced prolonged major life stress showed greater glucocorticoid receptor resistance, and that resistance predicted higher production of local inflammatory cytokines when those people were exposed to a virus. Notably, their actual cortisol levels didn’t predict inflammation. It was the tissue-level resistance to cortisol’s effects that mattered, not how much cortisol was in the bloodstream. The practical result is that chronically stressed individuals mount a larger, less controlled inflammatory response to everyday immune challenges.
Poor Sleep
Both total sleep deprivation and partial sleep restriction raise CRP levels. In controlled experiments, CRP concentrations climbed during both conditions but stayed stable when participants slept normally. This matters because CRP is one of the strongest predictors of cardiovascular risk, with levels below 1 mg/L considered low risk, 1 to 3 mg/L moderate risk, and above 3 mg/L high risk.
Disrupted circadian rhythms cause broader problems beyond a single night of bad sleep. Shift work and irregular sleep schedules alter the normal daily cycling of immune cells, increasing susceptibility to infections. Long-term circadian disruption causes epigenetic changes to genes that regulate inflammation, including the gene for TNF-α, a central inflammatory cytokine. These aren’t temporary shifts: chronic shift work has been shown to change the methylation patterns of core circadian clock genes, potentially reprogramming how the body handles inflammation on a lasting basis.
Physical Inactivity
When muscles contract during exercise, they release signaling molecules called myokines that have anti-inflammatory effects throughout the body. Several of these compounds stimulate fat burning and oxidative metabolism. Without regular muscle contraction, those anti-inflammatory signals go quiet, and the balance tips toward a pro-inflammatory state.
Bed rest studies in healthy adults illustrate this starkly. Extended muscle unloading shifts the body’s immune profile toward inflammation and simultaneously increases visceral fat, compounding the problem. Sedentary behavior essentially removes one of the body’s built-in anti-inflammatory systems while feeding the pro-inflammatory cycle through fat accumulation.
Alcohol
Alcohol damages the gut lining and shifts the gut microbiome toward gram-negative bacteria, which carry lipopolysaccharides (LPS) on their outer membranes. As the intestinal barrier weakens, LPS leaks into the bloodstream. Even in people without liver disease, acute alcohol consumption significantly increases circulating LPS levels. LPS binds to immune receptors on liver cells and triggers NF-κB signaling, the same inflammatory master switch activated by trans fats, producing a wave of inflammatory cytokines.
Chronic alcohol use amplifies every step of this process. It increases nitric oxide production, upregulates NF-κB signaling, and alters gut-related molecules that further increase intestinal permeability. The result is a self-reinforcing loop: more gut leakiness, more bacterial toxins in the blood, more liver inflammation, and more systemic immune activation.
Gut Barrier Breakdown
Even outside the context of alcohol, anything that weakens the intestinal lining can drive inflammation. The gut barrier is a single layer of cells held together by tight junction proteins. When those junctions loosen, bacterial metabolites and endotoxins like LPS enter the circulation, a state sometimes called “leaky gut.” LPS activates a receptor called TLR4 on immune cells, triggering two distinct signaling cascades that ultimately activate NF-κB and produce inflammatory cytokines. The intensity of this inflammatory response depends on how much LPS crosses the barrier and how quickly immune cells internalize and process it.
Factors that compromise the gut barrier include a low-fiber diet, chronic stress, certain medications, and the high-fructose intake described earlier. The gut microbiome and the immune system are in constant conversation, and when the barrier between them breaks down, the immune system treats escaping bacterial components as an ongoing infection.
Air Pollution
Fine particulate matter (PM2.5) from vehicle exhaust, industrial emissions, and wildfire smoke triggers measurable systemic inflammation. Research conducted during the 2008 Beijing Olympics, when pollution levels shifted dramatically due to regulatory controls, found that PM2.5 exposure increased immune cell infiltration in the lungs, spleen, and visceral fat. Macrophages and neutrophils, two frontline immune cells, accumulated significantly in these tissues during high-pollution periods. After the Olympics, when pollution restrictions were lifted, the immune response was even stronger, with macrophages, neutrophils, and lymphocytes all elevated in the spleen and lungs of exposed subjects.
This means air pollution doesn’t just irritate the airways. It activates immune cells far from the lungs, in fat tissue and immune organs, contributing to the kind of whole-body inflammation linked to cardiovascular disease and metabolic dysfunction. People living in high-pollution areas carry a baseline inflammatory burden that compounds the effects of diet, stress, and other factors on this list.