One of the things that helped me was an article on weight loss from Christian Womanhood, the magazine published by First Baptist Church of Hammond, IN. The article is gone from the website now, and I can't find any archives, but I saved the main points of it earlier, so I can still share them with you now. I just love these two suggestions for beginning a weight loss effort!
"1. Make your weight situation a matter of daily prayer. When you receive this issue of Christian Womanhood, you will be “smack dab” in the midst of Christmas and New Year’s and all the rich, caloric food that goes with the holidays. But I’m asking you to pray and ask God every day for the following:
• the dress size and/or weight that would be pleasing to Him, pleasing to your husband, and that would help you to be at your best.
• the strength to have the victory in this area of your life.
• the wisdom to make right decisions about your plan of weight control.
• to help every woman reading this article who is struggling with her weight and that this column will be a source of hope and help to her.
Being overweight (or underweight, by the way) is a spiritual problem. I know my flesh, and my flesh doesn’t want anyone telling it what to do. But my spirit wants to be used of God, and so they war against each other. It is God’s will for you to have victory, and one of the first steps is making it a consistent matter of prayer.
2. Memorize II Corinthians 10:3-5. “For though we walk in the flesh, we do not war after the flesh: (For the weapons of our warfare are not carnal, but mighty through God to the pulling down of strong holds:) Casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ.” Everything God does He does through His Word. We must get the Word of God into our minds and into our hearts."