A placebo is a sham substance or treatment that is designed to have no known therapeutic value. Common placebos include inert tablets, inert injections, sham surgery, and other procedures. The critical effect of a placebo is the expectation.
Colours may play a role in it too.
Blue for Sleep
Red as a Stimulant
Yellow for AntiDepressants
When it comes to Placebo, it is more about higher order thinking - The brain.
Old drugs such as Prozac are becoming less and less effective when faced with the placebo effect. How come real medicine isn't fully replaced by placebos then?
It is because of the deception factor, doctors are required to take a Hippocratic Oath of ethics, which was historically taken by physicians. It is one of the most widely known Greek medical texts. In its original form, it required a new physician to swear, by a number of healing gods, to uphold specific ethical standards.
While there are such things as the Placebos, Nocebos exist too and focus on Medical treatment that creates harmful effects on a patient, for instance a placebo capsule of a painkiller that may give one headaches, would be given to an individual and then explained of its possible effects of headache - this would result in the patient experiencing these psychosomatic effects, hence the nocebo name.
Overall, a placebo won't help you lose weight or reduce the size of your tumor. As an alternative, placebos are effective for neurological symptoms like pain perception. Though they may alleviate symptoms, placebos are not effective treatments. Most studies have found that they are useful for alleviating symptoms associated with cancer treatment, including fatigue and nausea.
However, I ultimately believe in the power of the placebo effect and its possibility of contributing to the breakthrough of modern medicine and health.