I use the app myfitnesspal and it is the only thing that helps me lose weight, I've lost 12lbs since November and that's including over Xmas too :) 

I have the same problem, as my depression/anxiety flare up I lose too much weight, then try to gain it back and go too far. MyFitnessPal (as everyone is saying) helps show you what you're eating. If I look at it around dinner time and I still have 1,500 calories left, I try to make sure I have a balanced, but higher-calorie meal. If I only have 200, I go for maybe a salad and milk. It also helps show you what nutrient you have had for the day, to better choose which food to eat.

I also use My Fitness Pal. Since I always have my phone with me anyway, I don't mind logging in food while I eat throughout the day. I'm not on a diet. I'm simply becoming more aware of what I'm eating, and eating smaller amounts of the less healthier things. I've also found a few at-home workouts that I love to do. I love doing different types of aerobics, and finding routines, and instructional videos on YouTube. You don't have to go to the gym, or on a run, to get the exercise you need. Just look for something that fits into your everyday life, and something that you enjoy doing. I wish you the best of luck! 

Create a plan and stick to it. Consistency is key. Start reading about eating healthy and exercise. Knowledge is power. Stay away from fad diets. <----if it's something that you can't commit to for life than forget it. For me, eating clean has been huge. Learn where your food is coming from and it will drive you to eat healthy! 

Paleo diet. It's super hard but if you can get through the first two weeks it all becomes easier. That and running. I lost over 30 pounds doing that over the summer. Good luck. Remember abs are made in the kitchen not the gym ;)

Any unsalted seeds as snacks or pomegranate