There is a lot of hogwash out there and this is one that I hear stated by people and normally, just like with a myriad of other myths these people who are absolutely confident that this is sage advice tend to be the fatter and less healthy members of a group.
If you hear a trainer saying this (for weight loss) than I would be willing to bet that said trainer is probably going to try to sell you something that aids in this process or direct you to a meal preparation partner who can make this magic cure available to you - and it is complete nonsense.
For example, I just did a quick search for "many small meals throughout the day" and of course thousands of websites popped up. I clicked on a few of them and lo' and behold all of them had something to sell you. This is normally a very good reason to be very suspicious.
However, if you go to sources that don't even have anything for sale and most of their articles are devoid of pictures and are very boring and academic such as The National Institute of Health they will show that they have done numerous studies on precisely this topic and discovered there is zero correlation between meal size and weight loss. NONE.
So who do you think is more trustworthy in this situation? Some random website that just happens to be selling something that is exactly what they are suggesting is the "best way" or a national institute that actually performs science to figure out a real answer and coincidentally doesn't even have anything to sell you?
The fact of the matter is this: Your body doesn't know how to differentiate between how much you eat in total and how much you eat every time you eat something. Your body is always burning calories the same way that your car will burn gasoline the entire time it is on. What if someone told you to fill up your car with just a little bit of gasoline 5 times a day to make it go faster? Would you believe that hogwash?
Now if you are a bodybuilder, eating many times a day is necessary because you need a steady flow of protein to be coming in at all times. The top guys will actually wake up every 4 hours in the night in order to drink another protein shake, but these guys do a LOT more work in the gym than normal humans and are a very special case.
The bottom line here is that if anyone out there ever suggests that eating the same amount of calories spread out over many meals is somehow going to help you lose weight is either physiologically ignorant or is trying to sell you something - and since that thing they are trying to sell you doesn't work anyway, they are probably best avoided.
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