Neuropathy is a painful and potentially crippling disorder that is common in people with diabetes and often affects people with obesity, yet the underlying reason is poorly understood. Boyd al. now reveal that a diet enriched in ω-6 polyunsaturated fatty acids (PUFAs) triggers peripheral neuropathy in mice, and this effect is reversed by a diet enriched in ω-3 PUFAs. These findings may help explain the high incidence of neuropathies in people with diet-related obesity without diabetes, and may provide a potential target for the prevention and treatment of this metabolic and neurological disorder.