It seems like an idea gets started and without much proof, gets repeated.
The “eat 5-6 small meals per day which will stimulate the metabolism” is one such myth. There have been a number of studies recently published that compared people eating 5-6 small meals throughout the day versus people eating the identical number of calories but in the typical three-meals-per-day approach. These studies show that there is zero increase in metabolism or fat loss by consuming 5-6 smaller meals during the day.
In addition, there are some studies that show that in obese people who follow this 5-6 meal a day plan gain more fat and experience overall worse health.
Finally, eating this frequently puts a strain on the pancreas which can lead to diabetes.