I admire you for both recognizing the problem and seeking help. Single parenting is difficult; changing your daufghter's eating patterns will demand even more from you. :(
First, though, comfort eating is not an eating disorder. That's kind of like saying loneliness is a mood disorder. Neither is a disorder; both indicate an unmet need. Both should be handled with empathy and kindness.
Foods to encourage and avoid
Lucky for you, at 9 years of age, she has a limited ability to buy her own food, so you have a lot of control over what she eats (as opposed to how much.) The first step is fairly straightfoward: remove from the house any unhealthy foodstuffs, including (but not limited to):
- sugary drinks and snack-type foods
- salty and fatty type snack foods, especially crunchy stuff (the whole food-science of crunchiness mandates a lot of processing and also often fat)
- candy, especially chocolate
- ice cream
Keep only healthy foods in the house. Few people want to eat two oranges in a row, but if they do, many fruits are mostly water. It's incredibly hard to binge on pomegranates. Grapes have fewer calories than raisins. Yogurt is better than ice cream. Avocados and almonds can provide healthier fats. An avocado smoothie is a wonderful thing; you can share one.
Substitutes for eating
A warm and loving conversation is a salve for many wounds, and doesn't contain any calories.
Lead by example; be sure to model healthy eating habits for your child.
Dissociate food from rewards (don't reward with a trip to the ice-cream shop or pizza palace.)
Look for patterns to disrupt. Disrupt them with a different activity she might enjoy or share a healthier snack with her while having a nice conversation where she has a chance to unload any problems she might be dealing with.
Make sure she has a good emotional vocabulary (I think this is really important for all kids, more so for kids experiencing issues.) Naming an emotion is a first step to understanding it and then awareness of how one is dealing with it.
Encourage journaling (see above; needs vocabulary.) Journaling acknowledges self awareness by pondering events and how they made you feel, e.g. it made me happy/angry/lonely/grateful/envious/excited/hopeful? etc. If it takes, she'll have a tool to deal with her emotions other than reaching for food.
Help your daughter to explore other ways to deal with emotions, brainstorming with her some other ways to deal with emotions which trigger her eating. Some kind of exercise when she feels stressed out, reading a good book if she's bored, arranging a play date or sleep over to look forward to if she's feeling lonely, etc.
Dance with her. Seriously. Sometimes when my kids were bored, I would put on some upbeat or funny music and we would dance. We would pretend to tango, waltz (lots of twirling), rock & roll (tells you how old I am); I would teach my kids the dances of my youth. We had so much fun that we ended up all taking ballroom dancing as a family.
These are just the beginning. Reading about healthy foods, lifestyle changes, and emotional eating will give you more helpful advice.
Again, I really admire your willingness to explore this issue with her (and us).