Background and Rationale: Overweight and obesity were progressively associated with increased ischemic stroke, in a meta-analysis pooling 25 studies. However, ‘obesity paradox’ was also reported for stroke in that obesity or overweight was protective of stroke. Across the spectrum of Body Mass Index (BMI), ‘who has the most risk’ remains unclear, when major risk factors were controlled. Methods: A large cohort from Taiwan, N = 469,088, successively recruited during 1994–2008 with comprehensive health screening data, was followed up with National Death file. Stroke risks for underweight (BMI