Sorry, but I don't believe any food can help you loose weight!
You have taken the first positive step and joined the gym. What you need to do is put a healthy eating plan into place to compliment your efforts in the gym.
Lets not beat about the bush here - it is hard work to loose weight - but if you really want to you can do it.
I lost 2 stone in 6 months - through exercising and controlling the AMOUNT of what I ate.
I tried to exercise EVERY day. That meant that the days where I hadn't been to the gym where the exception not the rule. If you are serious about loosing the weight you should aim to go to the gym every day (or run for 40mins around where you live/ power walk for 1hour etc.) - in reality this won't happen, but then it will be outwith your normal routine as opposed to fitting the gym/exercise into your current routine.
With regard to food - the more you exercise the healthier you will want to eat - it kind of just happens! If you have to go out for a meal then when you are given your food, immediately cut it in two and leave one half at the side of the plate - apparently Princess Anne does this all the time and she, despite other more glamerous members of the Royal Family taking the limelight, has maintained a trim figure throughout her life!
If you want to weigh in each week but can't be bothered going to a class (like me!) then try the Tesco e-diet. You have to weigh in each week and they will give you menu plans to suit your diet and what you want.
Good luck! You can do it - 40 minutes intensive exercise a day for 6 months (this is only 5 days if you were to exercise on a non stop training session!) and a controlled diet will do it!

I have no tips about food but try pancreatin from solgar. It's a digestive enzyme. Apparently lots of us have weak digestive systems and this can let us down. I found this fantastic. I am a sugar addict and had a serious pot belly. Taking this flattened the pot belly. The digestive enzymes by Solgar are good too but this one is stronger and much better.

eat carbs for breakfast and any dairy after about 11 no carbs or dairy without exception except for eggs lunch and supper = protein plus veg or salad afternoon snack = fruit go easy on citrus fruit couple weeks of this and you should see a difference if you do this long term 1 day a week you can eat what you like advantage of eating like this means you get your carbs in for energy, dont lose weight too quick so you wont pile it all on after plus after a while you adapt this eating plan for long term which actually works well with your digestive system. i know someone who has lost 18 kilos in 6 months on this also not restrictive so you dont feel you are on a diet.