Diet Myth News Flash: Snacking Will NOT “Boost Your Metabolism”.

Snacking metabolism
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Snacking metabolism
News flash: you can quit packing 5 snacks when you go to the office.

“Eat every 1.5-3 hours.”

“Be sure to snack frequently to keep your metabolism elevated.”

“Don’t skip meals or your body will go into starvation mode.”

I’m quite guilty of preaching messages like this as if they were the gospel of fitness and nutrition. As early as two years ago, I was telling clients and writing in magazines to “eat small, frequent meals so you keep your metabolism elevated” or to “graze like a squirrel so that you burn more calories”.

But eventually, I realized this wasn’t true.

It started when another, more informed nutritionist asked me to drag out the research studies that proved that eating more than three meals per day would elevate the metabolism.

So for two weeks, I combed research journals, the National Institutes of Health, library books, and every resource I could get my hands on.

And guess what?

I could find zero evidence that eating any more than three meals per day does any good at “boosting your metabolism”, “burning fat” or “losing weight”.

Basically, as long as your total caloric and nutrient intake stays the same, then your metabolism, at the end of the day, stays the same as well. One study that carefully demonstrated this, published in The British Journal of Nutrition, randomly assigned overweight men and women to very strict low-calorie diets and followed the participants for eight weeks.

Each subject consumed the same number of calories per day, but one group ate three meals a day and the other ate six meals a day. Both groups lost significant and equivalent amounts of weight, with no difference between the groups in fat loss, appetite control or hormones that signal hunger and appetite. Other studies have had similar results.

Especially compared to the reliable metabolic boost of exercise, frequent snacking or “grazing” doesn’t do much at all for you.

As a matter of fact, when you restrict feeding times to three meals per day your body produces more anti-aging and muscle building hormones.  When you eat more than three times per day, you produce more fat-building and age-accelerating hormones. By keeping your blood sugar levels constantly elevated with snacking, you never really allow your body to learn how to reliably burn fat as a fuel.

So where did this “snack frequently” myth come from?

There are two basic reasons this myth has been perpetuated.

The first goes is the annoying false message of “starvation mode.”   The idea behind this is that when not much food is around, the body burns fewer calories in order to conserve energy, just in case the food shortage continues. In ancient times, during a famine, you’d need to live on your stored fat, and down-regulating your metabolism seems like a pretty good way to do this.

This seems to makes sense, but it’s only partially true. Your body does respond to a long period of very low calorie intake by slowing your metabolism to conserve energy – but it takes about three days of complete fasting or very low calorie restriction for your body to do something as drastic as down-regulating your metabolism.

Last time I checked, we didn’t have a serious problem with people who don’t snack going on 3 day fasts or eating 500 calories a day.

The second way this myth probably got perpetuated is because of something called the thermic effect of food, which basically refers to the fact that when you digest food, your body has to burn some calories in order to do that.

So if you eat a meal that contains 300 calories, your body might burn up to 30 calories digesting and absorbing that meal.

And this has led some people, including many famous personal trainers and nutritionists, to assume that if your body is constantly digesting food, then it will constantly be burning calories. So if you go too long between meals, you shut down that “calorie burning fire that you’re supposed to be stoking”.

The truth is this: at the end of the day, the thermic effect of food is identical – whether you ate three times, five times, or ten times. This is because the thermic effect of food is based on the total quantity of food, and not on the frequency of food intake.

Ultimately, if you’re eating fewer than three times a day, research has suggested that you may end up eating a less healthy diet or gaining weight. But this is probably because you’re ravenous by the time you get to dinner after having fasted for 10 hours since breakfast (and vice versa) and not because anything magical happens to your metabolism when you snack all day.

I personally do it like this:

-breakfast between 7 and 9

-lunch between 1 and 2

-an afternoon snack before my workout

-dinner between 6 and 8

When I’m in hot and heavy training for something like Ironman, I throw in one additional meal: a snack of whey protein, Cocochia and coconut milk before I go to bed.

And that’s it. Compared to my old strategy of trying to eat 6-10 times per day, this is way easier. Interestingly, it’s also much easier to maintain weight, and I more completely digest my meals.

Grazing is for cows. So free up some time, quit trying to “snack every 1.5-3 hours”, and just eat when you’re hungry. If you have feedback, questions or other comments, simply leave them below!

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24 thoughts on “Diet Myth News Flash: Snacking Will NOT “Boost Your Metabolism”.

  1. Always good to ask, “Why?” Thanks for your research, Ben. It reinforces that simplicity–here , 3 meals–ought to be respected until proven otherwise.

  2. Thanks so much for the information and clearing up the myth. My eating schedule of meals and snacks is similar to yours with different times. It works well for me and it is reaffirming to here it from you! Thanks!

  3. Great post! I think we will see more studies coming out that supports this. I think in my latest Women's Health mag it touches on this theory. For so long we have been trained that fasting will induce starvation mode and screw up your metabolism, that's going to be a hard one to combat with the general population until more information comes out like this. Thanks BEN!

  4. If this is right — and I have no reason to doubt that it is — then I don't quite understand how intermittent fasting should help anyone to lose weight. That is, if you're eating the same number of calories as you otherwise would but are doing so in a condensed window, then you'll take in, and burn, the same number of calories under an IF regime as you would in a normal regime. Accordingly, the thermic effect is the same, etc. At this point, I know that IF'ing has worked for me, but I'm not sure I know why.

    1. With IF, you get increased enzymatic activity of fat burning enzymes and upregulation of carbohydrate storage enzymes. You can also get some telomere lengthening (anti aging) activity. So it goes beyond calories.

  5. Hi Ben – I've been with you since show #1 and it's been fun to see how you're gravitating toward the simple solution (difficult for the more technical, science, A type). Einstein said "If the solution is simple, God is answering". This post (and other recent ones) and your podcast Q&As and interviews are taking the simple, common sense approach which is fantastic – eat when your hungry, drink when your thirsty, just choose wisely the food and drink you consume – beautiful. Our bodies are magnificent creations and able to marvelously regulate the numerous functions in the body. Our hunger and thirst mechanism serve a purpose (the "drink before you're thirsty" idea is idiotic in my opinion, for example). So appreciate your sound, logical, and common sense advise, Ben. Cheers!

  6. Thank you Ben. Good to spread the word to help people reach their goals easier, with less frustration and with more fun. Thanks for this article.

    1. I suspect what you mean is does that raise blood sugar enough to, for example, "shut down fat burning". In my opinion, that's not really important. I'm talking about significant snacks, like a handful of trail mix, a yogurt, etc.

  7. Fantastic article – Excellent review & presentation of the evidence – thanks a million for making it relevant & understandable!! Thanks a million

  8. Thanks Ben! I was one that subscribed to the eating 6 small meals a day would keep your metabolism revved up and burning all day. What I found is that I gained more fat and weight and it is harder to get it off eating that way. Now I'm trying to only eat when I'm hungry. My eating schedule is similar to yours only different times.

  9. Thanks for the great research info Ben – this is the difference that got me following you to begin with! Paula sums it all up! :) And again it all comes down to do what works for you – LOL. I know I eat a lot of little meals because getting more than 400kcals in a meal is killer – though I am one of them folks that tends to under rather than overeat…

  10. I disagree, you should never be hungry and you should never be thirsty. We should fuel our bodies not feed them. You don't mention low caloric healthy snacks to limit the hunger before meals. If you are hungry, really hungry you 're going to over eat. Did you know that the leading cause for daytime fatigue is dehydration. We need to stay hydrated to stay healthy.

    1. I think there is crucial difference between “hungry” and “starving”. When I am hungry I notice that I would enjoy having food and not purely for emotional reasons but because my body wants it. If I don’t pay attention and go far beyond that point I am shaking, cooking dinner and trying not to eat it as I go, I have hunger pain in my stomach and I eat much faster. I don’t think there are many people that think that sounds like a good idea.

      But knowing what the first signs of hunger are is difficult to learn because we often dint pay attention, either we starve ourselves and that during reaction is the first sign we took notice of it, or we constantly feed ourselves do we never get to know what hungry feels like.

      The same goes with water, if to you being “thirsty” is having a parched mouth and suddenly NEEDING water then the chances are you weren’t paying attention to any of the other little things.

      I have, in the past forced myself to drink the recommended daily amount of water…I hated it. It made me feel bloated, sick, sleepy from being bloated and it made me resent drinking water.

      And I saw no benefits from it, I didn’t feel more alert, my skin want clearer and more hydrated, the only physical difference is that every twenty minutes I needed to pee.

      I think listening to your body and trusting the system to let us know what it needs is pretty important, the more I do that the better I feel.

  11. This is interesting, I have heard that myth all my life, and not from dumb, ill educated people, but from trainers who studied hard, love what they do and have only your best interest at heart.

    So it really is interesting to see how deeply a myth can penetrate, but I guess in the world of nutrition and exercise there is always some new research, New study, New “best way”to do things that sticking to those old standards seems like the obvious choice.

    I am personally trying to lose weight…a lot of it, but in the past few days I have been busy and have had a very low appetite. I make sure I eat the right food but I just have nut been interested in eating and I was upset at thinking how much damage I could be doing by not snacking and guiltily trying to get some snacks into my day even though doing so made me feel sick. I was never starving and I ate when I was hungry and until I was content but the guilt was there. Thank you for this, it takes a strong and open minded person to change an strongly held position of their own and admit to that!

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