You can't help her with that. She needs to decide what to eat and when. However, you need to understand that weight loss is similar to a chinese finger puzzle. When you stop trying to solve it, it's solved. What I mean by that is, let's say you are really hungry for ummmmm, New York style cheesecake. Now, you know that the cheesecake is bad for you and not exactly diet food. But you are really craving the cheesecake.

Best plan? EAT THE CHEESECAKE. If you don't eat the cheesecake, your hunger is not satisfied. So you load up on "healthier" snacks and you end up eating 3 or 4 times as many calories loading up on "healthier" snacks because your hunger is never satisfied. You really want cheesecake, so your hunger is not going to go away until you eat CHEESECAKE. Got it?

If your girlfriend was sneaking fast food late at night, then you (yourself) might be part of the problem that is preventing her from losing weight. If she feels she has to hide her eating, that is a problem. Or it could be her own guilt. That is, maybe you don't care if she's eating junk food, but she might THINK that you would disapprove.

Best you can do is encourage her to eat what she wants to, but be sensible about it. Like, if she wants that fast food burger, then she should eat the fast food burger. As a regular meal though. Not an extra meal in the middle of the night....

I am someone who has struggled with my weight as well. What I did is join an organisation called Slimming World, which is in the UK and Ireland. If you are in the UK or Ireland, it might be worth looking into. If not, there might be a similar programme. Weight Watchers for example.

Basically, I eat loads but I mainly eat healthy, hunger satisfying low calorie foods. I never go hungry and that might be where your girlfriend has gone wrong. If she's starving herself half to death trying to live on carrot sticks or something along those lines, she's not going to be able to sustain it. Eventually, she is going to be ravenously hungry and just end up binge eating as she appears to have done. She should eat three good meals a day, with lots of fresh fruit and vegetables (frozen works fine too), lean meats (visible fat removed), fat free yogurt, beans and pulses, some cereals and bread but not much and really cut down on high fat and high sugar foods.

If she does that, she might be surprised by the results. I have lost 6 and a half stone doing that.

Stop buying her ass happy meals