Many people have started eating six smaller meals throughout the day rather than three, hoping to boost their metabolism. Health professionals have differing opinions, making this a subject of much debate.

According to an article from 101weightloss.com, eating 5 to 6 smaller meals daily will "definitely boost your metabolism." This is a very confident claim for a subject that hasn't been heavily studied. I noticed many magazine articles also claimed mini-meals as their secret to a faster metabolism. While they backed up their claims with some general science, they did not go into detail. Other sources had different opinions. Writer, Krisha McCoy, from Everyday Health concluded that your metabolism will be maintained no matter how many meals as long as you don't go too many hours without food and enter in starvation mode. An article on Medicinenet.com says that while there is not enough evidence to determine if there's a difference, one thing we do know is that breakfast is the most important meal of the day. Both of these sources said at the top that they were reviewed by health professionals.
So, while there may not be a clear answer, it seems that we can rely more on the last couple sources that say multiple smaller meals throughout the day do not boost your metabolism as some sources claim. Whether you're eating 3 meals or 6, what's important is the total number of calories consumed and making sure to start your day off with a healthy breakfast.
Sources
http://www.101weightloss.com/articles/eat-six-meals-a-day-2.htm
http://www.everydayhealth.com/weight/boosting-metabolism-with-mini-meals.aspx
http://www.medicinenet.com/script/main/art.asp?articlekey=56254
Perhaps the most important factor in a person's dieting is their attitude. With a constant conscious effort to eat much differently than normal, by changing the traditional three meals a day regimen, a person might develop healthier habits. If eating become a higher priority, as it was a more frequent part of their thinking, perhaps they would be more apt to change the way in which they eat. The actual health effects of six meals rather than three might not be the diet, but simply the effect of a lifestyle change.