We understand your concern for your mother's health and we are here to support you in prayer and counsel. We commend you for bringing your requests in Jesus' name, as it is only through Him that we have access to God the Father. As it is written in John 14:6 WEB "Jesus said to him, I am the way, the truth, and the life. No one comes to the Father, except through me."
Firstly, let us address the issue of gluttony, which is a sin that is often overlooked but needs to be addressed. The Bible tells us in Proverbs 23:20-21, "Do not be among ones who drink too much wine, or among those who gorge themselves on meat, for the drunkard and the glutton shall become poor; and drowsiness clothes them in rags." We need to remind your mother that her body is a temple of the Holy Spirit and that God calls us to honor Him with our bodies. As it is written in 1 Corinthians 6:19-20, "Or don't you know that your body is a temple of the Holy Spirit who is in you, whom you have from God? You are not your own, for you were bought with a price. Therefore glorify God in your body and in your spirit, which are God's."
Your mother's belief that she does not need professional help may be a sign of pride, which can hinder her healing and transformation. We must remember that God uses various means to bring about healing, including professionals in the field of health and nutrition. As it is written in James 5:14, "Is any among you sick? Let him call for the elders of the assembly, and let them pray over him, anointing him with oil in the name of the Lord," so too should your mother be open to seeking help from those whom God has gifted with knowledge and wisdom in health matters.
Let us pray together for your mother:
"Heavenly Father, we come before You in the name of Jesus, lifting up our dear sister who is struggling with her health due to an addiction to food. Lord, we acknowledge that this is a sin and we ask for Your forgiveness and healing. We pray that You would convict her of this sin and give her the strength to overcome it. We ask that You would open her eyes to the need for professional help and that You would guide her to the right people who can support her in this journey.
Father, we pray for her complete healing and transformation. We ask that You would help her to develop healthy habits that honor her body as a temple of the Holy Spirit. We pray that You would give her the discipline to maintain a healthy lifestyle and that You would bless her efforts to lose weight and keep it off.
Lord, we also pray for her spiritual health, that she would draw near to You during this time and that You would draw near to her. We ask that You would fill her with Your peace, joy, and strength as she walks this journey.
We ask all these things in the precious name of Jesus Christ, our Lord, and Savior. Amen."
Be encouraged, dear one, for God hears your prayers and He cares for your mother. Trust in Him and continue to support your mother in love and truth. As it is written in Philippians 4:13, "I can do all things through Christ, who strengthens me." Remind your mother of this truth and encourage her to depend on Christ for her strength and victory.
Prayer Focus: God, Thank You. Thank You for loving me. God, I ask You in Jesus’ name bless me with everything that I stand in need of and everything You want me to have. Bless me to know You in truth, fall in love with You with all my heart, mind, soul, body, and strength and never fall out of love with You. Bless me to have an ever growing closer stronger, more intimate relationship with You. Bless me with the love, desire, strength, and the spirit of obedience to always delight myself in You, seek first Your kingdom, and Your righteousness. Help and strengthen me God to always respect and obey You. Bless me to trust You with all my heart, acknowledge You in all my ways, and lean not to my own understanding. 
