I am not sure when this myth started or how it gained its popularity. Maybe it is due to a multi billion dollar industry that relies on people consuming snacks throughout the day in order for it to make a profit. But I digress. The myth states that when you consume smaller meals throughout the day your metabolism will increase more versus larger less frequent meals. This is based off the concept of thermodynamics. Put simply, when you consume calories your body requires energy to digest that food. Therefore, if you eat more frequently then your body would have to use more energy to digest the food, and this is completely correct. Unfortunately, your metabolism doesn’t care about how many meals you consume, all it cares about is the total number of calories. Whether you eat three meals or six meals, if the calorie total is 2,000 calories than the metabolic effect from the food will be the same regardless of how many meals you eat. And I am not alone in this thinking. A study done on 15 subjects ( 7 males, 8 female) assessing energy expenditure between three meals versus six meal over a 24 hour period found no difference between the two.
In fact, the study concluded , “increasing meal frequency from three to six per day has no significant effect on 24-h fat oxidation, but may increase hunger and the desire to eat.”(1).
Another study found the same conclusion pertaining to the desire to eat, “The results from this study in 12 healthy adults do not support the popularized notion that small, frequent meals help to decrease overall appetite.” (2)
In order to understand why a higher meal frequency may potentially cause an increase in appetite we have to look at another study that asked this same question. The study was done on the effect of feeding frequency on insulin and ghrelin in human subjects. It is believed that insulin reduces ghrelin levels to signal fullness. Ghrelin is a hunger signalling hormone that influences your appetite. Higher levels of ghrelin will increase your appetite and vice versa. The study’s goal was to figure out whether or not meal frequency influenced insulin’s effect on ghrelin.
The study found the following, “This study provides further evidence that the postprandial fall in ghrelin might be due, at least partially, to the rise in insulin and that high-frequency feeding may disrupt this relationship.” (3)
The three studies prove that a higher meal frequency has no benefits versus a lower meal frequency, but could be more detrimental due to its effects on increasing appetite. Instead of counting your meals I recommend you stick to a 12 hour eating window, but we will discuss that next week.