So apparently you can now think yourself slim by telling yourself that you are eating something healthy. Scientists have found that people's metabolisms speed up when they believe they are eating something high in calories, regardless of how fattening the food is. Studies were performed on people to assess their hunger's hormone 'ghrelin' through drinking the same calorie milkshake but labelled them as really high calorie and very low. Levels dropped in ghrelin when thinking they were drinking the higher calorie shake which also means metabolism drops too.
To read more on this check out the link -
Daily Mail - http://www.dailymail.co.uk/health/article-2605109/How-THINK-slim-Your-metabolism-speeds-body-thinks-eating-high-calories.html