Blueberries, strawberries, raspberries, Goji berries and acai berries are powerhouses of nutrition. They are abundant in vitamins and minerals, and are also some of the best sources of antioxidants. Berries also contain a healthy dose of fibre, which slows your carbohydrate absorption and digestion, and controls blood sugar levels to help prevent insulin spikes, making them superfoods for fat loss.