Systemic inflammation has direct and measurable effects on body composition through several interconnected mechanisms. It drives insulin resistance, which promotes fat storage. It raises cortisol, which promotes muscle catabolism and abdominal fat deposition. It disrupts the hypothalamic signalling that regulates appetite. Reducing dietary inflammatory load is therefore not just a health goal. It is a body composition strategy.
The Insulin Resistance Pathway
Pro-inflammatory cytokines, particularly interleukin-6 and tumour necrosis factor alpha, interfere with insulin receptor signalling in muscle and fat tissue. This produces insulin resistance, a state in which the body must produce more insulin to achieve the same glucose uptake. Higher circulating insulin promotes fat storage and inhibits fat mobilisation. A dietary pattern that drives chronic low-grade inflammation is therefore a dietary pattern that promotes fat accumulation, independent of caloric intake.
The Cortisol Pathway
Systemic inflammation activates the hypothalamic-pituitary-adrenal axis, stimulating cortisol release. Cortisol promotes gluconeogenesis from muscle protein and drives visceral fat storage through its action on adipocyte cortisol receptors, which are most dense in the abdominal region. Adults with central obesity consistently show elevated inflammatory markers, and the relationship is bidirectional: inflammation drives visceral fat storage, and visceral fat is itself an endocrine organ that produces pro-inflammatory cytokines.
The Practical Dietary Priorities
- Eliminate ultra-processed foods before making any other dietary change
- Increase oily fish consumption to three servings per week minimum
- Replace refined cooking oils with extra-virgin olive oil
- Increase vegetable variety to 30 or more different plants per week for microbiome diversity
- Reduce alcohol consumption, as alcohol is one of the most powerful drivers of intestinal permeability and systemic inflammatory load