The South Beach Diet works, for most people. Its low fat, low carb approach helps you lose weight quickly and easily. Health benefits are great too.But there's some easy mistakes you must avoid.Gain Weight in Phase 2Most people do well being strict in Phase 1. But what happens when you switch into Phase 2 ? Often, you put some weight back on again. Why ? Because your body's starved of carbs for 2 or 3 weeks. At the start of Phase 2 it grabs at every carb you give it, and turns them into fat. I .