For carbs, I find them essential. The key is the right type - nothing white or packaged. In fact the brains main source of energy is glucose (from carbs); otherwise many people get 'brain fog'. Vegetables and fruits are excellent and whole grains like spelt, millet, oats, quinoa.
From my experience for someone to have proper sustained weightloss the buildup of toxins have to come out. This is because toxins are stored by the body in your fat cells - this is a protective mechanism. If weight comes off but toxins stay in the body the toxins will be concentrated and the body will gain again.