Obese patients with psoriasis are more likely to have both severe skin disease and treatment-resistant psoriasis than non-obese patients. Systemic inflammation is characteristic of both obesity and psoriasis, and an overlap in function exists between adipocytes and immune cells. Several studies show weight loss through diet, exercise, and calorie restriction can reduce severity of psoriasis. Bariatric surgery may alter the inflammatory milieu, which may improve skin disease. Specialized diets other than calorie restriction have not been shown to improve psoriasis. Patients with coexisting celiac disease may benefit from a gluten-free diet. We review the existing literature and evidence linking psoriasis and obesity.