what is placebo effect , can it help us to change our body , can we use for losing weight ???

Recent studies show that if humans minds think positively about their goals and, think the way that they are going through is true, the way that they are going through will be beneficial for them, so by this if you put your mind to rest and give your brain the ability to believe easily in what you want your brain will help you to achieve your goal easier
for example, if you think that a banana can help you to remove cancer, this will become true but you need to think about it and believe in the banana, you cant say to yourself that banana can help me with my cancer while you truly don't believe in it.
And this is not just for a banana you can think about anything else for example, losing weight, make your brain think that eating junk foods can make you lean so by this you will be able to lose weight and become leaner