Skipping meals, intermittent fasting, grazing, etc.

or… Circadian Meal Timing!

They say if you’re going to [intentionally] skip a meal, it should be breakfast – and hey, that’s probably the easiest meal to skip.  However, a recent study showed skipping dinner FTW (well, not exactly).  I’ve never seen a proper study directly comparing the effects of skipping different meals, but here are a few that come close.  The findings may surprise you.

omelette

note: with the exception of Fernemark (Exhibit B), these studies are mostly macronutrient-controlled. That is, protein, fat, and carbs are similar between the groups; the only thing that differs is when they were ingested.  This can be tricky and/or very nuanced in some instances, like if dinner was smaller (fewer calories) but more protein-rich, for example… but in order to include 5 relevant studies and not bore you to death, you’ll have to check the full texts for those details.

Exhibit A.

This is the one that made headlines:

Eating two larger meals a day (breakfast and lunch) is more effective than six smaller meals in a reduced-energy regimen for patients with type 2 diabetes (Kahleova et al., 2014)

The study lasted 12 weeks and the researchers provided a LOT of the food for the participants.  They achieved a decent caloric deficit in both groups primarily by restricting fat intake.

Kahleova data

Body weight and fasting blood glucose decreased more so in the participants who skipped dinner.  The authors speculated that more weight was lost because energy expenditure was better preserved, although I’d say it’s just as likely due to a greater reduction in food intake or a larger increase in physical activity, as each of these findings were equally statistically non-significant.

Kahleova data 2

So, two meals per day (skipping dinner) produced greater weight loss and better metabolic improvements than grazing (6 smaller meals per day).  And grazing didn’t “boost metabolic rate,” or at least not resting energy expenditure (see Figure i, above).

Exhibit B.

Next up: low fat vs. low carb vs. skipping breakfast (“Mediterranean” diet).  Hat tip to “Liberrocky” for this one (and for inspiring this post)… this is also the only study where macronutrient content was varied.

A randomized cross-over trial of the postprandial effects of three different diets in patients with type 2 diabetes (Fernemark et al., 2013)

This study is fundamentally different from the others because it only lasted one day.  And here’s how their glucose and insulin fared throughout said day (remember: low fat [solid lines] vs. low carb [big dashes] vs. skipping breakfast [small dashes]):

Fernemark data

As expected, glucose remained low in those who skipped breakfast, then spiked just as high as those on the low fat diet after lunch.  And for the low carbers, glucose levels were moderate after breakfast and low after lunch, also as expected.  For the most part, insulin levels followed suit with the exception that they were modestly higher after lunch in those who skipped breakfast (Mediterranean dieters).  Physiological insulin resistance?  Maybe, but the Mediterranean lunch was twice as big as the low fat lunch.  So, perhaps it was exactly enough insulin to prevent hyperglycemia.

The insulin AUC was just as high in the breakfast-skippers as in the low-fat dieters, and significantly lower in the low carbers.

Low carb fared better than skipping breakfast in this acute scenario.  Some might speculate that skipping breakfast while following a low carb plan (as opposed to a higher carb Mediterranean diet) may have been better.  I won’t argue against that.

Exhibit C.

High caloric intake at breakfast vs. dinner differentially influences weight loss of overweight and obese women (Jakubowicz et al., 2013)

Total daily nutrient intake was similar in both groups, with the meals basically flipped – either a big breakfast or a big dinner.  It’s not skipping a meal per se, but the small meal (either dinner or breakfast) was very small (215 kcal)… pretty close to skipping a meal…

Jakubowicz 1

It’s not a direct comparison, but similar to the findings of Kahleova (skipping dinner FTW), this study showed a big breakfast was better than a big dinner for weight loss.  Much better:

Jakubowicz 2

Insulin sensitivity and fasting blood glucose also improved more with big breakfasts:

Jakubowicz 3

It’s possible that Kahleova’s and Fernemark’s studies were less about skipping a meal at a particular time of day, dinner or breakfast, respectively, and more about intermittent fasting vs. different degrees of “grazing” …but Jakubowicz’s findings show that more calories earlier in the day produce better outcomes for weight loss and metabolic status, which is similar to Kahleova’s skipping dinner (which is essentially the same as having more calories earlier in the day).

Exhibit D.

Jakubowicz’s findings were mimicked almost exactly, albeit with less statistical significance, with this one:

Big breakfast rich in protein and fat improves glycemic control in type 2 diabetics (Rabinovitz et al., 2013)

No statistical significance, but those assigned to big breakfasts ate slightly more but lost slightly more weight and body fat.  Fasting glucose also improved more.

Rabinovitz 1

What DID reach statistical significance, and is of arguably much more importance, was a greater reduction in anti-diabetic medication use in the big breakfast group:

Rabinovitz 2

Exhibit E.

Morning meal more efficient for fat loss in a 3-month lifestyle intervention (Lombardo et al., 2014)

The intervention in this study was smaller: 70% vs. 55% of total calories provided in the first half of the day.  Despite the two interventions being so similar, those who ingested a greater portion of their calories earlier in the day lost more weight and body fat, and experienced greater improvements in glucose and insulin levels:

Lombardo

 

Conclusion:

Intermittent fasting (via skipping dinner) was better than grazing (Kahleova).

Skipping breakfast (Mediterranean diet) was better than low fat but not low carb (Fernemark).

Every other study showed more calories earlier in the day yielded better outcomes:
Jakubowicz: superior weight loss.
Rabinovitz: greater reduction in meds.
Lombardo: more loss of weight and body fat.

And all of these things were, for the most part, relatively independent of “Eat Less, Move More.” #NutrientPartitioning

This may be unpopular, because skipping breakfast is more convenient for many people, but the consistency of these findings across a wide range of diets and study designs suggests, collectively,

Adelle Davis

calories proper

For more on alternative meal frequencies, see The Pocket Guide to Intermittent Fasting.

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  • http://www.caloriesproper.com/ William Lagakos

    Greater weight loss and hormonal changes after 6 months diet with carbohydrates eaten mostly at dinner.

    http://www.ncbi.nlm.nih.gov/pubmed/21475137

    • jasmine johend

      Thank you Bill, I enjoy lurking and reading your blogs. I’m confused though about the relationship between eating and cortisol. Woo has written in blogs that it is better to eat less during the day and work off the stress hormones, and then have a protein heavy dinner at night. I am maintaining a 100lb weight loss doing this but these studies confuse me about whether what I am doing is detrimental in the long term.

      I am one of those who if i eat too early in the day my appetite is stimulated and I just want to eat and eat, almost bordering on binging. Whereas the longer i can put off eating the better my appetite control. So is this pointing that it is better to eat during the day when the cortisol levels are high? I do try to do exercise after my evening meal for BS control.

      • http://www.caloriesproper.com/ William Lagakos

        Hi Jasmine,
        Congratulations on your progress! Maintaining a 100lb weight loss is very different from what was looked at in these studies. I’d say to keep doing what you’re doing (because it’s working).

  • http://drdrewdahlgren.com Dr. Andrew Dahlgren

    Great summary of several studies. Fasting can be arraigned to either skip breakfast or dinner. We as a society seem so programmed around dinner-usually only meal busy people eat together. Keep up the great posts.

    • http://www.caloriesproper.com/ William Lagakos

      Thanks, Andrew. Good point about “family dinners” (seems to be far more common than “family breakfasts”).

  • johnnyv

    Skipping breakfast is easy for me, much easier than skipping dinner. I find it hard to get to sleep on an empty stomach. Although who knows maybe after a couple of weeks I could be trained to a new eating pattern. Main advantage of skipping breakfast is that I have time for decent dinner prep after work.

    • http://www.caloriesproper.com/ William Lagakos

      “Although who knows maybe after a couple of weeks I could be trained to a new eating pattern.”

      This was exactly my experience when I started exercising in the morning (and decided I needed to eat beforehand).

  • Kindke

    I think LC can mimic alot of the benefits of IF. and although the data suggest a big breakfast is “best” I still refute this. In my experience I prefer skip breakfast, big lunch, followed by moderate dinner.

    Im still convinced that this mostly boils down to managing lipogenesis and fat burning in the liver. specifically activating ppar(alpha) in the liver.

    • http://www.caloriesproper.com/ William Lagakos

      “…LC can mimic alot of the benefits of IF.”

      I think some people believe this very fervently!

      Also, theoretically, skipping breakfast or dinner yields feeding & fasting windows of similar duration… so there are likely other factors involved in the nutrient partitioning and metabolic effects …which favored skipping dinner in the studies cited above :p

      • Kindke

        its tough to argue with raw data BUT insight does beg the question, generally people are just not hungry in the morning, so why eat when not hungry?

        should we drink when we are not thirsty? Exercise when we are feeling tired?

        Eating a big breakfast just feels “wrong”. after big meals you are tried and lazy and encumbered therefore less productive.

        I would NEVER consider it optimal eating before going to the gym in the morning. My exercise performance is superior when fasted. One day I tried 40g of whey before the gym in the morning and it was a disaster, I felt tired and unmotivated/sluggish the entire time not to mention borderline hypoglycemic.

    • Wenchypoo

      I remember when I ate big breakfasts–to think about it now makes me gag. I could NEVER eat that amount of food these days!

  • http://www.caloriesproper.com/ William Lagakos

    Timing of food intake predicts weight loss effectiveness.

    http://www.ncbi.nlm.nih.gov/pubmed/23357955

    “Late lunch eaters lost less weight and displayed a slower weight-loss rate during the 20 weeks of treatment than early eaters (P=0.002). Surprisingly, energy intake, dietary composition, estimated energy expenditure, appetite hormones and sleep duration was similar between both groups. Nevertheless, late eaters were more evening types, had less energetic breakfasts and skipped breakfast more frequently that early eaters (all; P<0.05)."

  • http://cristivlad.com Chris

    I’d consider that cortisol plays an important role here, especially when the subjects are diabetics.

    • http://www.caloriesproper.com/ William Lagakos

      that was actually reported in many of the studies… but beyond the scope of this post.

    • Wenchypoo

      Speaking of cortisol, I imagine most cases of road rage stem from diabetes or lack of BG knowledge/control.

  • Jeff Rothschild

    Good stuff as always! Skipping dinner FTW isn’t surprising to me as I’m much more in favor of eating while the sun is up rather than a strict 8 hour feeding window (especially 12-8, and especially in winter!), but I’d love to add a few thoughts to the discussion…

    A ‘light’ or even moderate dinner eaten while the sun is still up should be no problem, and a feeding window of 8-12 hours could easily include both breakfast and dinner.

    AM cortisol spike is good, that’s why breakfast with protein is amazing, and a carb-only breakfast of cereal and pop tarts is garbage. Though I feel like I’ve seen some evidence to the contrary, protein spikes cortisol more than other macros. http://www.ncbi.nlm.nih.gov/pubmed/10204975

    PM cortisol spike is not so bueno. And circadian rhythms of glucose tolerance http://www.ncbi.nlm.nih.gov/pubmed/1566835 would tell us a big evening meal is also not so bueno.

    Carbs towards the end of the day work better probably due to non-insulin dependent glucose uptake, but too far into the evening and it would probably be detrimental considering the rises in leptin, GH, gluconeogenesis, and melatonin.

    Does that all seem plausible?

    • http://www.caloriesproper.com/ William Lagakos

      “a carb-only breakfast of cereal and pop tarts is garbage.”
      +1

      “PM cortisol spike is not so bueno.”
      +1

      “Carbs towards the end of the day work better…”

      this might get a little tricky. Like you said; also: http://caloriesproper.com/?p=4654

      • Jeff

        I’ve remembered that melatonin post of yours for a while and I’ve had a lingering question…. melatonin is the expression of darkness in all animals, yet nocturnal animals are the opposite of us and so melatonin would signal their active phase. So when we look at those studies and see things like melatonin suppression of lipolysis, wouldn’t we need to reverse that and assume melatonin enhances lipolysis in us?

        • http://www.caloriesproper.com/ William Lagakos

          Melatonin functions to conserve energy in both species. It’s frequently thought of as a sleepiness hormone, but I don’t think this is very accurate.

    • http://www.caloriesproper.com/ William Lagakos

      P.S. great comment. Thanks!

  • Jack Kruse

    Bill welcome to the Leptin Rx. LOL.

    • http://www.caloriesproper.com/ William Lagakos

      I knew a protein-rich breakfast was part of it!

  • Dustin Sikstrom

    You know Bill, after having experimented with skipping breakfast, skipping lunch and skipping dinner, also even doing a 20/4 (4 hours straight eating in the evening) and even warrior dieting, with enough time to “adapt” to feeling good, I’m convinced at least for myself, that my sleep quality dramatically improves when I stop eating at least 4 hours before bed. I find I sleep soundly and wake up extremely energized and ready to go.

    Sadly the downside is if I don’t eat a final meal and eat only lunch at say noon, then I wake up at about 3 AM ready to go, even on only 5 or so hours of sleep. This isn’t good because it drains me in the day. So basically I just have to move my lunch later to about 3-5 PM. So a solid breakfast at about 7 AM to carry me through until about 2-3 PM, sometimes having something small was optimal for energy and sleep quality.

    Talk about a connection between circadian rhythm and feeding! ;)

    • Kindke

      Dustin I agree with the not eating too close to bedtime. I found that out aswell when doing the warrior diet !

      If I tried eating my big main meal at 7-6 in the evening my sleep would be shit. But If I shifted the meal to 3-4pm things went much better.

    • http://www.caloriesproper.com/ William Lagakos

      Breakfast plus a late lunch seems like a pretty good compromise for people who don’t like the idea of skipping dinner.

  • http://ashsimmonds.com/ Ash Simmonds

    More confounding exhibits which I’m sure we’ve probably gone over before (summarised here):

    - http://highsteaks.com/forum/health-nutrition-and-science/intermittent-feasting-fasting-meal-frequency-532.0.html

    “Hypercaloric diets with increased meal frequency, but not meal size, increase intrahepatic triglycerides: A randomized controlled trial”

    - http://www.ncbi.nlm.nih.gov/pubmed/24668862

    “The effect on health of alternate day calorie restriction: eating less and more than needed on alternate days prolongs life”

    - http://www.ncbi.nlm.nih.gov/pubmed/16529878

    “Increased meal frequency does not promote greater weight loss in subjects who were prescribed an 8-week equi-energetic energy-restricted diet”

    - http://www.ncbi.nlm.nih.gov/pubmed/19943985

  • Wenchypoo

    Body weight and fasting blood glucose decreased more so in the participants who skipped dinner. The authors speculated that more weight was lost because energy expenditure was better preserved, although I’d say it’s just as likely due to a greater reduction in food intake or a larger increase in physical activity

    It’s all about the length of the fast–the more time you can go without food, the lower your BG goes…especially the fasting number. The same thing happens when you sleep in on weekends–the longer you sleep, the longer the fast, and the less eating you do. Hubby’s FBG is always lower over the weekends when he gets to sleep in.

    So far, his best BG-lowering combo is: a high-protein dinner + either cooked veggies or cold potato salad on Friday and Saturday nights. Then, his FBG is in the 70′s. We can’t do this food regimen too often, because the charm wears off after 2 back-to-backs–I already thought of making this his sole diet, and tried it.

    I just try to keep his protein and fiber up during the week. Then, he’s in the 80′s-90′s unless he has to take a pain-killer.

    Since he works out on an alternating schedule, he does without lunch–he works out MWF in the mornings before work, so he eats “breakfast” instead of lunch (I pack it to go just like a lunch). On TTh, he swims after work, and comes home to dinner to refuel.

    As for me, I can easily do without breakfast, since my stomach doesn’t wake up until about 10 or 11. But to go without dinner means interrupted sleep.

  • valerie

    Sorry to nitpick about the math again, but I don’t understand the results in the Lombardo table.

    The difference in body weights has a mean of 1.7 and an stdv around 3.2. They report a p-value of 0.028.

    The difference in fasting insulin has a mean of 4.9 and an stdv around 1.0. They report “ns” (which I understand means p-value > 0.05).

    How are those results possible? I am not even asking how the exact p-values were calculated. I am wondering how those two sets of results can coexist. To me, it seems obvious that the second one should be much more significant than the first one. Am I getting something wrong?

    • http://www.caloriesproper.com/ William Lagakos

      Statistical Analysis:

      • valerie

        Ah, I see. Thanks.

  • maria

    Hi. I know this is off-topic but can you please give me your insight on the Autoimmune Protocol? I have Hashimoto’s, and raynauds. I am still not sure what’s the best diet to follow for someone with Hashimoto’s Thyroiditis. I am already eating a paleo diet, more like PHD (rice and potatoes – 100g a day carbs) and trying to incorporate intermitting fasting and an 8h feeding window. I read other opinions on how people with thyroid issues shouldn’t do intermitting fasting so I’m confused. On a side note I used to be hypoglycemic, I believe my thyroid issues are somehow involved. A protein based breakfast helped alot.
    If you could give me your opinion on the AIP , and when its best to eat carbs, feeding windows, IF, etc I would appreciate it. I find your knowledge trustworthy and I respect and value your work.

    • http://www.caloriesproper.com/ William Lagakos

      Hi Maria,
      Thanks for the kind words.

      I don’t know very much about Hashimoto’s, but I recently wrote a post about thyroid function – you might find some of the information useful. (http://caloriesproper.com/?p=4231).

      As to meal timing and fasting windows, there’s this post, and the Pocket Guide (http://caloriesproper.com/?p=3269)… it’s hard to give specific recommendations because context is so very important.

  • FrenchFry

    I am usually a “PM eater” and stick to black coffee in the morning. After reading this article, I tried to reverse my eating time, for the fun of it. After a week into it, I can say it’s not for me: I felt sluggish and sleepy. Today I reverted back to my usual timing: energy is back. I can’t say precisely if this is due to the type of food that could be inadequate in the morning (I usually eat whole foods, regardless of macros so a bit of everything) but I won’t do that again, just not my timing.

    • http://ashsimmonds.com/ Ash Simmonds

      No offense Frenchy, but if I/we believed everything someone who tried a diet/regime for only a week had to say then some of us might never have pushed through to proper keto adaptation etc.

      Unfortunately most science studies are only 1-2 weeks too, but in reality we know that it’s really difficult to acclimatize to something in less than a few strict months.

      • FrenchFry

        Yeah, well, I knew I would get some feedback about the duration of my little experiment. No prob. I don’t think it is important anyway in my case as I have no weight to lose.

        About “proper keto-adaptation”, mmm, I guess it takes a few weeks, maybe more, when you come from the usual SAD-like WOE. But I don’t think it is necessary for weight loss. I think Bill wrote something about it (high protein, low cal diet are as good to increase ketone concentration – but do you really need it as a steady state ? not convinced at all).

        • http://ashsimmonds.com/ Ash Simmonds

          Ok, 99% of my meals are 95%+ fatty meat.

          Say I decided to go vegan for a few days and declare it bullshit because I felt like crap…

          Look, I’m not putting junk on your results, but if anyone tells me they’ve changed a major life habit for a week and are feeling crap… It’s not because of the habit itself, it’s the individual fighting the new habit.

        • http://www.caloriesproper.com/ William Lagakos

          yup, I wrote that. The ketogenic diet seems most beneficial for obese patients, to help induce an energy deficit. For “steady state,” or maintenance of a reduced body weight, all bets are off. Ymmv.

          • jasmine johend

            I have being trying keto and I can’t get more than 0.6 on ketone meter at the most,0.2 being the average. I assume I eat too much meat; I feel like something is missing if I don’t get my large portion of meat. I know Rosedale and few others advise less meat for health reasons (mTOR, cancer). I worry about the amount of meat/seafood I consume. Bill if bets are off for keto for maintenance, then what do you believe is the optimum. I am very interested in your views.

          • http://www.caloriesproper.com/ William Lagakos

            I don’t put too much stock in excessively restricting protein, especially seafood and organ meats, for health purposes.

            Also, higher protein was the strongest predictor of weight loss maintenance in the longest study I know of (…2 years? iirc). Low carb always does well also (not necessarily keto), and is probably equally important if prone to insulin resistance.

            That said, “maintenance” is the hard part… and it sounds like you are doing well, no?

          • mikemarkham

            I eat mostly meat and probably average between 0.8 and 1.3. If you’re in ketosis, you’re in ketosis. Being in deeper doesn’t have any added benefit from what I’ve read.

            If I do my weekly 24-hour fast (water only), I’ve gotten up to 3.8 on my ketone meter. That was my highest ever. I didn’t really need to test because I’m a fairly good gauge at what my present levels are by how I’m feeling.

            I’ve been maintenance keto for over three years and feel great.

          • http://www.caloriesproper.com/ William Lagakos

            Thanks for the info, Mike.
            If you don’t mind me asking, are you in it for weight loss/maintenance or general health?

          • mikemarkham

            I lost all the weight I needed within a couple of months. I stick with it for health benefits and prevention potential.

    • http://www.caloriesproper.com/ William Lagakos

      Hi FF, yeah, it seems as though the ability to tolerate big changes in meal timing and/or frequency vary widely depending on the person doing it.

  • Wenchypoo
  • http://www.caloriesproper.com/ William Lagakos

    “A recommendation to skip breakfast for weight loss had no discernable effect on weight loss” 1.usa.gov/1izfuYe

    • Thomas Hemming Larsen

      But they didn’t control what they ate at breakfast. I have to say that after following Kiefer’s CN/CBL principles of no carbs in the first half of the day I feel and look better. The reasoning is that you want to avoid an insulin spike in the morning because both fat and muscle tissue are so keen on soaking up the glucose at that time of day. By avoiding carbs you can stay somewhat ketogenic and mobilise more fat.

      • http://www.caloriesproper.com/ William Lagakos

        Also, adipocytes are ALWAYS keen on soaking stuff up. Morning, noon, and night.

        As to the skipping breakfast vs. skipping dinner: it seems like, in practice, it’s gonna be a personal lifestyle thing. The difference between the two practices isn’t huge.

        The studies tend to suggest dinner might be a better meal to skip, but that obviously wouldn’t be optimal for someone who exercises later in the day, for example.

        • Thomas Hemming Larsen

          Hehe, but if only there’s a slight difference it might be enough for some to justify changing dietary patterns.
          Doesn’t most people agree that exercising in the afternoon is best? Or is that just in the ‘paleo’ community…