If you eat tasty food and then you say Alhamdulillah (praise be to God), this is a very low level of thanksgiving, for it is based on observation and taste, and is not on a high plane of thanksgiving.

The high level of thanksgiving which befits man is when food is placed before him, he is reminded of the entire creative system. He thinks that all these food items were formerly raw materials. By a very superior process God converted these into food. In this way, through a universal process, all these food items came into existence.

Then he starts thinking that all these food items, in their initial form, could not be a source of energy for himself. Therefore, God went further and created a very complex digestive system. This is an automatic system of digestion. Whenever you eat anything, this digestive system miraculously converts these food items into living cells; these living things are then converted into flesh and blood in the body. On thinking like this, such an ocean of thanksgiving wells up within you that you fail to find words to express your intense feelings.

From this example, one can understand what is a lower level of thanksgiving (shukr) and what is a higher level of thanksgiving. If you give thanks on a basic level, you will always live in ungratefulness. For a high level of gratitude you need to give thanks on a noble human level. But these are the things which are least found in the world (The Quran, 34:13). The kind of gratitude God desires from a human being is always on a higher level. A lower level of thanksgiving is not acceptable from humans.

Source: Discovering God