temperature. thats a biggie when boosting your metabolisam. you always want to drink cold water--freezing! it boosts your metabolisam, because your body starts working harder to keep your body warm, therefore, burning more calories ;)
you want to also take cold showers(this is not a must, i know alot of you out there love your hot showers:) ). and keep your temperature down at night--you burn aproximently 65 calories when you sleep, keeping your temperature low burns another 65.
but! people who are anorexic tend to be cold too, so try to avoid hand holding and hugging around ana-educated friends/family.