How do we know this? Consider this teaching of Jesus:
“And why do you worry about clothes? See how the lilies of the field grow. They do not labor or spin. Yet I tell you that not even Solomon in all his splendor was dressed like one of these. If that is how God clothes the grass of the field, which is here today and tomorrow is thrown into the fire, will He not much more clothe you, O you of little faith? So do not worry, saying, ‘What shall we eat? Or ‘What shall we drink?’ or ‘What shall we wear?’ For the pagans run after all these things and your heavenly Father knows that you need them. But seek first His kingdom and His righteousness, and all these things will be given to you as well. Therefore do not worry about tomorrow, for tomorrow will worry about itself. Each day has enough trouble of its own.” (Matt. 6:28-33)
The bottom line is that God takes care of us regardless of whether we ask for it or not. This fact is often used by atheists to show people who pray for food that their prayer is worthless, because the atheists get to eat too, and sometimes even more than those who pray for it.
The reality is that God has designed nature to provide each species with their allotment of food, assuming that each of us takes what we need and shares the rest, rather than hordes it - which is what is taking place in human society today. There is enough food for everyone by His design.
Still, as Jesus states above, having plenty of food will not fulfill our real craving - the need for spiritual fulfillment.
This tells us we really do not have to pray for food, as Jesus’ teachings illustrate, because physical food will not satisfy us. This is because we are not these temporary physical bodies. Our identities are not physical, but are spiritual. We are the spirit-persons who drive these temporary physical bodies. Jesus emphasizes this throughout his teachings, including this statement:
“Do not store up for yourselves treasures on earth, where moth and rust destroy, and where thieves break in and steal. But store up for yourselves treasures in heaven, where moth and rust do not destroy, and where thieves do not break in and steal. For where your treasure is, there your heart will be also.” (Matt 6:19-20)
The “bread” Jesus is referring to in Matt. 6:11 is our relationship with God. We need to love and serve God as our heart and soul. This is confirmed in the previous stanza of the prayer:
"Your kingdom come, Your will be done."
By serving God we become part of his intimate kingdom, and we grow in our love for Him, which feeds us spiritually. Loving God and serving God becomes our daily bread.
We need this love for God every day. We need this loving relationship with God all day long. We need this loving relationship or we become spiritually hungry. Without this loving relationship we are seeking satisfaction from all sorts of different things, trying to fill the empty void caused by not having this intimate relationship. This is confirmed by Jesus elsewhere:
" 'Love the Lord your God with all your heart and with all your soul and with all your mind.' This is the first and greatest commandment." (Matt. 22:37-38)