actually, differing opinions on the idea that thinner=more flashes. see study here, where more abdominal adipose = more flashes.
Menopause. 2008 May-Jun;15(3):429-34
CONCLUSION: Increased abdominal adiposity, particularly subcutaneous adiposity, is associated with increased odds of hot flashes, favoring thermoregulatory models of hot flashes. Body fat may not protect women from hot flashes as once thought.