Offal means organ meats which primarily includes liver and kidney but also includes heart and tongue. They are cheaper cuts of meat if you are on a budget. One of the main reasons for starting the list with offal is that it contains very little fat, yet has high quality protein. 

The next keto diet food is eggs. Eggs are very versatile and they can be used in cooking, baking or eaten on their own. Ideal for breakfast, they contain protein which is of course one of the main reasons why you eat eggs; but all that protein comes with fat as well. The keto diet recommends high-fat during the first few weeks so eating eggs will provide you with a delicious fat in the yolk. 

Butter and coconut oil are great but try and add some olive oil to your meals. Olive oil is not a saturated fat so is much better for your heart. Other healthy fats come from eating olives so these are great to have in the fridge. 

Nuts, a keto staple, are another source of healthy fats and are great for snacking on. When you are on a keto diet you cannot have all those carb-loaded snacks like biscuits, chocolate cakes and crisps (chips). Nuts make a great snack, as do seeds - pumpkin seeds are one of the best. 

To get a healthy dose of fat and protein when on the keto diet try to eat full-fat dairy products. Cheese is probably the best example, but again just be careful not to overeat it as it can add up quickly in terms of calories if you do.

Fish can sometimes be overlooked on the keto diet but consuming oily fish, in particular, provides your body with essential omega3 fatty acids. Omega 3's are anti-inflammatory and are necessary to try and offset the inflammatory nature of the keto diet. Tinned mackerel, salmon and small fish such as sardines and anchovies are great to have in your store cupboard.