What are the benefits of loving-kindness meditation?

The strongest evidence is for positive affect and self-directed kindness. Galante and colleagues reviewed 22 randomised trials in 2014 and reported moderate effects on depression, mindfulness and compassion against passive controls, plus a smaller effect on self-compassion. Positive emotions improved against an active comparison. Two caveats matter: the review covered kindness-based practices broadly, not metta alone, and the authors called the results inconclusive for some outcomes, particularly against active controls. Fredrickson and colleagues reported in 2008 that seven weeks of practice raised positive emotions, which built personal resources, which in turn predicted life satisfaction.