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Hypothalamic inflammation then leads to leptin resistance. Disrupting the leptin feedback loop
You might have heard of insulin resistance, the condition where people’s cells stop “hearing” insulin signals, and slowly lose the ability to control their blood sugar levels. The same thing can happen with leptin: Your brain can start to ignore or “tune out” the leptin, even if you’re eating enough, and have plenty of energy stored in your body fat. In insulin resistance, the pancreas can simply pump out more insulin to keep blood sugar under control (at least for a while). Since body fat is our main leptin factory, to make more leptin, we need more body fat. When you’re leptin resistant, your brain thinks it doesn’t have enough leptin.
The brain needs the leptin factory (i.e. body fat) to get bigger and produce more leptin. Operation Add Adiposity begins. You feel hungry. Regular portion sizes are no longer satisfying; it’s harder to feel satiated and you want to keep eating and eat more often. You gain fat. Mission accomplished, or so your brain thinks. Here’s what the leptin feedback loop looks like now, in this disrupted scenario: As if that weren’t enough, it seems this inflammation and resulting leptin resistance might even cause our bodies to defend our increased weight. (This seems to be because the brain now views this higher level of leptin and body fat as its new normal.)
