No bread, rice, pasta, fruit, potatoes or sugar.
If you are being really strict, no alcohol either.
Focus on meals based around protein, fattier cuts of meat/fish wherever possible, and accompany with low carb veg.
Eggs are a perfect source of protein.
Salad is ideal - with an oily dressing and/or mayonnaise.
Other low carb veg - cauliflower, broccoli, spinach, celery, mushrooms, watercress, asparagus, fennel, courgettes.
Fry them in butter/put dollops of butter on them when serving.
Cut out dairy (butter is still allowed) if you can - if you can't, then at least keep it to a minimum. So keep the cream/yoghurt/cheese to a minimum.
Drink lots of water.
Avoid artificial sweeteners.
Good luck!