I used to wear a weight belt when I worked out in college (and was squatting 120+ pounds), but I now think they are not that useful unless you are an Olympic weightlifter lifting REALLY heavy weights for 1-2 reps. You can become dependant on their support, which means the core isn't doing its job of supporting you. Instead, it's best to train your core to support you, and not try to lift heavier than you can safely without a belt.