Starting & Stopping

If you rely on motivation for weight loss you'll keep losing and gaining. Motivation is epheremal and fleeting; what you need is to eat at a calorie deficit for an extended period of time. Eating less calories than your body uses will result in weight loss. Eating at maintenance once you get down to your goal weight will keep off extra weight gain.

What are your concrete reasons for wanting to lose weight? Are you thinking of weight loss as a finite thing instead of a whole of life change? Do you think that once the weight is off you won't ever have to monitor your calories again, and can eat the same way you used to, which is what caused you to put on weight in the first place?

Forget about motivation. Eating at a deficit doesn't require it. What it requires is eating less every day, and weighing/logging whatever you eat. It doesn't matter what you eat as long as it's within your calorie totals. A balanced diet with more nutritious food may help keep you full and less likely to nibble, and you'll get the carbs, proteins, fibre, vitamins, minerals, fats etc that your body needs, but you can eat what you want. No food is off limits, but if any foods trigger bingeing, they're best avoided until you can learn to have them in moderation.

The issue with you seems more behavioural. Try and change how you eat, and don't rely on motivation to see you through. Don't restrict food you like because you have some idea that those foods are bad for you and will make you put on weight. Overeating any food will cause weight gain. You've lost weight before; this time you have to stick at it, not give up because this magical motivation you were expecting to regulate your appetite or keep you from eating didn't do what you thought it was supposed to.