Eating less food is less expensive. One way to decrease your weight is to just decrease the amount. This will cut your food costs. While you will spend more money on fruits and vegetables, you will make up the difference by spending less on expensive junk food. I don't like diet foods.
Weight change is a gradual process.
Invest in clothing that is comfortable. Wear a belt or scarf to accentuate your new waistline. It's much easier to take in a seam than to let it out. Buy clothing for the long-term goal. Sometimes the first weight loss is from salt and water.