All animal products are rich in fat .Not just the visible fat 'hat you see in the fat around a piece of steak or bacon even a piece of lean beef has a fat content of 10 % but did you ever see a fat vegetarian?Meat,pouetry and fish were are not originally part of man's diet. Our teeth evoloved to deal with vegetables and not flesh. Our digestive systems are those of foragers ,not hunters. We cannot foage ourselves on meat and than go without using for many days as other ....do .
But meat is highly concentrated form of nutriment and is also among the most appetising of food in average diet .The flavour and smell of meat have encouraged many ways of eating.