If you aren't going to be particular about it, forget about following a keto diet. You can't be flippant about the exact science involved. The mathematics might seem simple — your daily intake of food must roughly comprise 75 per cent of fat, 20 per cent of protein and five per cent of carbohydrates. But implementing this strict rule starts with checking the label of every edible item you buy to find out what its nutrient contents are. And it ends with ensuring that your meals stick to the afore-mentioned fat-proteins-and-carbs ratio.