There are two types of fat associated with cuts of beef (or lamb) – intramuscular fat and external fat. Intramuscular fat, or marbling, gives flavour and keeps the meat moist. External fat is found around the outside – if you like your beef to be as lean as possible, make sure that you trim any excess external fat before cooking.
All you need to trim your beef is a sharp knife – simply slice away at the fat gradually (without slicing into the meat) until there is only a very thin, even strip of it remaining. Leaving this thin strip ensures that your meat will be moist and juicy.
See these tips in action in the Beef & Lamb video below:
For more great information about how to trim the fat off steaks, see The Spruce.