Ok here it goes . Most women who tend to need to lose weight have a slower metabolism. Easiest way to speed it up is to eat more times throughout the day. So basically snack in between meals, and when I say snack not crap snacks lol. The biggest meal of the day which is mostly usually skipped should be breakfast, after breakfast then a mid morning snack about 2 hours later, then lunch with lunch being her second largest meal of the day, and then a mid afternoon snack about 2 hours later. Then dinner, and dinner can be late it really doesn't matter if she will be eating and going to bed, however if she does this have her do another snack before dinner, and if not after dinner.
Now what I say is ok for snacks try supplements but only as snacks. Not mens protein powder and not usually what is at GNC. They have supps for women but they taste nasty and doesn't have enough fiber or low sugar etc. She should go Low calorie, mid protein, low sugar, high fiber. The best and cheapest place I found to use for these is Bariatric.com. Now the manufacturer of their supplements actually makes them for many many weight loss companies and brands them to whatever company they are selling to. It's all the same. The protein powders are sold in boxes of 7 packs with typically each pack containing 12-15g of protein, 90 calories, 4-6 grams of sugar and a few grams of dietary fiber just depending on the flavor you go with. These protein powders can be made as pudding or as shakes, and actually I have recipes where you can make cookies out of them, or even mix them with something such as pumpkin, and walaaa you have healthy pumpkin cheesecake!
Another sup they have are crunchies, like Cheerios enhanced with BBQ seasoning that have 12g of protein, but these should only be consumed once a day. (they have different flavors, just threw this one out there)
Now food, You may see me refer to a carb as a starch etc. What a lot of people do not know or understand is that there are many vegetables out there that are a veggie but are very high in starches and shouldn't be combined with another form of starch or carb. These veggies are Carrots, Potatoes, Peas, Legumes (unless she is vegetarian then this could be her source of protein) Nuts can also be considered in this group, and as a form of fat.
Really our body only needs 1 form of a carb other then when we receive these carbs in fruit. So basically she should in a day be consuming 2 servings of fruit, 1 starch or additional carb, and a serving of dairy a day. 1 fat counted outside of these things, along with an optional item such as a serving of salsa or salad dressing that is fat free, and 4-5 servings of vegetables, with 4 oz of protein for dinner, 2-3 for lunch or breakfast, and 1-2 for breakfast. Have her eat the fruits and starch/carb in the morning or for lunch. Her body will be able to burn these off easier. For dinner, only meat and veggies no carbs/starches at all. Try to put her at 1000 calories. Her first 3 days will be hard very hard, but once she over comes that she it will be easy peasy. I have serving sizes and items outlined as how they count, but can't find it right now. So basically if she has a baked potato for lunch no other carbs. and should max her carb serving out at 80 calories. 4-5 servings of veggies can be more depending on the type of veggies. Lettuce is so minimal in calories that you can have a huge salad full of lettuce!
Since she wants to lose weight, make her accountable for it. Make her get on a scale before she starts first thing in the morning naked, and take a pic of her feet on the scale. and have her send that to you or someone who will hold her to this. Then again make her weigh in and take a pic 3 times a week and do the same thing. NEVER let her weigh at night. Also we all know people plateau, so take measurements, however, she won't begin to plateau until she's a month or 2 in this, so she should see weight loss every week, or you will know she isn't sticking to it. Cheat days, lets talk about this, you can't cheat all day! 1 meal, and cheat responsibly. If she's going to cheat, make her wait at least a month because it will offset the weight loss, and that day, use 5 supplements and eat only that until she has her cheat meal. If at all possible, switch her off of sour cream to Fat free greek yogurt. You can use this in many different ways and its very healthy.
And one more point lots of water. The rule of thumb, 1/2 her body weight in fluid ounces!