Mini-Meals & Metabolic Rates: Fact Or Fitness Myth?

OK, it's time to shatter another fitness myth.

Just this week, I got another one of those newsletters from a "fitness expert" with the following headline:

"Mini Meals To Speed Up Your Metabolism" which included this content:

Have you heard that in order to SPEED UP your metabolism, you should be eating MORE OFTEN? …by eating every 2 or 3 hours… your metabolism is FIRED UP to it's highest speed)…

No doubt you have heard this same information from multiple directions for years.

But is there truth to this which has now become "conventional fat loss wisdom"?

Or is it a fitness myth waiting to be broken through for information we can really use?

Here's My Question:

Do mini-meals fire up your "metabolism" (we should use the term "metabolic rate" anyway – "metabolism" is really so vague a term, even though it pushes all kinds of hot buttons).

Let's put it another way – if you are trying to "recomposition" your body to have a lower fat-to-muscle ratio, is it an advantageous practice to spread your meals for the day out to multiple "mini-feeds"?

Do  5 – 6 or more mini meals a day increase your metabolic rate as opposed to fewer meals per day of larger size each?

I've been researching the professional journals and papers for a several weeks and am ready to report in on my findings.

I'm taking a deep breath and am ready to launch!

This may be a bit lengthy, and is guaranteed to include some egghead sections (research abstract excerpts), so pop on your specs, grab a glass of your favorite hot (or cold) drink, and settle in.

What I Found Out

Perhaps the most significant journal paper I came across is a study on reported in the British Journal of Nutrition. This paper reviews "the epidemiological studies relating meal frequency to body weight, and attempts to integrate these with the results of physiological investigations on meal frequency and energy balance".

Simply put, this study investigates the question: is there evidence to support the prescription of multiple small meals daily as opposed to fewer, larger meals when it comes to inspiring a metabolic rate response that would impact weight? One of the strengths of this study is that it entails a review of the literature and results available from multiple studies.

[Reference: Bellisle F et. al. Meal frequency and energy balance. Br J Nutr. (1997) 77 (Suppl 1):S57-70.]

Guess what?  Over a 24 hour period, apparently there IS no difference.

So, Why Do I Keep Getting Those Emails From "Pros" About Mini-Meals and Optimal "Metabolism"?

OK, maybe you keep getting these too.

If not, I'm sure you see them all over the web, in the news, and repeated-as-mantra from many corners of the fitness universe.

Frankly, I used to say it too.

But as I started getting more and more fired up about looking behind many of these commonly-held beliefs in my quest to find the simple truths that really are going to serve us – or not.

It is not hard to figure out how the mini-meals-and-metabolism ball got started on its roll.

You see, there actually IS a phenomenon called "Thermogenic Effect of Feeding" (TEF – yes, it even has its own official acronym).  There IS a thermogenic – or heat producing (translation:  stimulated metabolic rate) effect every time you eat.  The extrapolation from this has been, well, then eat more often, get more thermogenic stimulation, right?

Not so fast.

According to the research, there is also a GREATER thermogenic effect from larger meals.  If you take the 2, smaller minis and fewer larger (in the research they are referred to as "nibble" and "gorge"), over a 24 hour period there is no difference of thermogenic effect.  The larger meals have a HIGHER overall thermogenic stimulating effect, the mini-meals have a smaller, though more frequent effect.  As a matter of fact, overnight metabolic rate induction from fewer larger meals was strong.

Evidently it all comes out the same in the wash.

A detailed review of the possible mechanistic explanations for a metabolic advantage of nibbling meal patterns failed to reveal significant benefits in respect of energy expenditure. Although some short-term studies suggest that the thermic effect of feeding is higher when an isoenergetic test load is divided into multiple small meals, other studies refute this, and most are neutral.

More importantly, studies using whole-body calorimetry and doubly-labelled water to assess total 24h energy expenditure find no difference between nibbling and gorging. Finally, with the exception of a single study, there is no evidence that weight loss on hypoenergetic regimens is altered by meal frequency.

We conclude that any effects of meal pattern on the regulation of body weight are liely to be mediated through effects on the food intake side of the energy balance equation.

Interestingly, in studies (as reported in the same paper) report an inverse relationship between "nibbling" and reduced body fat, there were multiple other influences that mitigated the findings, i.e physical activity, smoking status, alcohol intake, meal under-reporting)

The above review paper examined not only earlier observational work but also direct studies of varying meal frequency on either metabolic rate or weight loss. With the exception of one poorly done study, no connection found between varying meal frequency and any of the examined parameters.

No increase in weight loss, no relative overall increase in metabolic rate, no nothing.  Nada.  Zip.

They concluded that earlier studies finding an effect of meal frequency on weight gain (or loss) had more to do with changes in appetite or food intake, not from any direct impact on metabolic rate.

For example, early observational studies discovered that people who skipped breakfast were heavier and this still resonates with conventional thought today idea that skipping breakfast makes you fatter. The review points out that this may be confusing cause and effect: people often start skipping meals to lose weight.

Then Why Have We Gotten The "Mini-Meal Metabolism" Story For So Long?

My answer to this is partly conjecture, partly supported by the scientific papers.  Let's go with the scientifically supported first.

It is very difficult to monitor human subjects over a 24 hour period.  Thus, monitoring effects of smaller meals, more frequently, has been a "friendlier" process, from a research point of view.

Second, marketing madness, I suspect, has played a big role here.  What better opportunity for snack food companies, energy bar moguls, between-meal-shake folks, bodybuiding supplement companies, and every one else who wants us to buy their edibles?

(An interesting anecdote from my friend Brad Pilon, who researched meal timing metabolism extensively for his work Eat Stop Eat:  Brad worked for several years in the food-supplement-for-body-builders industry and will be the first to tell you that one of their key marketing tools was to hook this what I call "partial information". More on Eat Stop Eat in 5 Reasons To Try Mini Fasts and Mini-Fasts:  My 4 Month Report)

Am I Telling You To STOP The Mini Meal Schedule?

Of course not.

If you like the rhythm, and it suits your needs and is successful for you for a variety of reasons, do what works for you!

As a matter of fact, there ARE some reasons and circumstances in which mini meals may be the best choice, unrelated to TEF; that's the topic for another article.

But if you are doing the mini-meal routine because you understand that it provides advantageous metabolic rate boost, there just isn't the scientific evidence to support it.

© Lani Muelrath

What is your favorite eating rhythm?  What have you found works for you best?  Comments section below.