Steak fajitas These spicy beef fajitas are packed with fresh flavours and are surprisingly low in calories if you use lean beef. This is a healthy dinner that can form part of a diet of 1200–1500 calories a day. Each serving provides 434 kcal, 30g protein, 46g carbohydrates (of which 16g sugars), 12g fat (of which 4g saturates), 13g fibre and 0.7g salt.