Are Dietitians Wrong About Dinner Time?

OK, are dietitians wrong about dinner time? I’m about to reinterpret some 20 year old research, which really got me thinking. Though I might be mistaken, I think the experts are wrong, and the research is on my side. Such that the oft made recommendation to have or finish dinner around 6 pm is not, how is it they say it? “Evidence Based” :

Influences of fat and carbohydrate on postprandial sleepiness, mood, and hormones. Physiol Behav. 1997 May;61(5):679-86. Wells AS1, Read NW, Uvnas-Moberg K, Alster P.

Abstract
Paired studies were conducted in 18 healthy volunteers (9 men, 9 women) to investigate whether differences in mood and daytime sleepiness induced by high-fat-low-carbohydrate (CHO) and low-fat-high-CHO morning meals were associated with specific hormonal responses. Plasma insulin concentrations were significantly higher after low-fat-high-CHO meals, and cholecystokinin (CCK) concentrations were significantly higher after high-fat-low-CHO meals. Subjects tended to feel more sleepy and less awake 2-3 h after the high-fat-low-CHO meal, and ratings of fatigue were significantly greater 3 h after the high-fat-low-CHO meal than after the low-fat-high-CHO meal. The results of the present study are consistent with the hypothesis that there is an association between the lassitude experienced after a meal and the release of CCK.

My comments:

When I read the above research summary I get the impression that you really shouldn’t eat high fat meals if you need energy in the next couple hours. However, if you read the actual study and look at the graphs you see that both the high fat and high carb meals increased feelings of fatigue, and made the subjects feel more sleepy, with the high carb meal being just as bad or worse at various time periods of the 3 hours they looked. It’s not like they were hiding anything, it’s more that abstracts don’t always give the whole story. The paper had this fascinating quotes in the introduction:

“…subjects report feeling more feeble, dreamy, and bored and less excited, clear headed, energetic, quick-witted, friendly, sociable, and elated after lunch than they do before eating.”

stimulation of the mucosa of the small intestine, either by a small electrical current or by the inflation of a balloon, has been demonstrated to induce sleepiness and sleep in cats”

“The pattern of afferent impulses evoked during stimulation are similar to those observed during the digestion of food, suggesting that digestive activity may contribute to the induction of drowsiness after eating.”

So that, combined with a number of other papers I have been reading about meal timing, light/dark cycles and the disruption of circadian rhythms being associated with a number of problems including daytime fatigue, poor eating habits, and depression disorders, got me thinking.

Maybe the best time to eat, and to subsequently feel tired is right before you want to go to sleep, duh. It definitely makes me think that after dinner is not the time for kids to do homework. Plus, there is the recent blog I did on a study that found people (in general) regardless of how you manipulate them are most hungry at 8 pm, and least hungry at 8 am. Yet all you hear from food experts is the importance of a good breakfast, and how you should finish your dinner early, generally 6 pm, particularly if you want to lose weight. So over the last year of my intermittent fasting I had mostly started eating at 5-6 pm, more recently 7 pm, but now I think I should start enjoying my dinner at 8 pm, live large, and sleep like a baby.

Also it’s not that I haven’t been looking for research contrary to the late dinner idea. So far I have heard that late meals make sleeping difficult (OK maybe if you have acid reflux) but I have no difficulty sleeping after Thanksgiving dinner for sure. Thus far I have not been able to locate any research that found sleep compromised after eating in regular people. I’ve heard that early dinner’s help weight loss because they increase the fasting time after dinner and before breakfast. I’ll buy that, but it sure seems a Rube Goldberg way to go about it if a late meals do in fact make people tired (WHEN THEY NEED TO SLEEP) and people are naturally least hungry in the morning (WHEN THEY NEED TO BE AWAKE). It just seems to me a whole lot easier, more satisfying, productive, best for overall physical and mental health, to increase the post meal fasting period by skipping breakfast (and lunch while you’re at it). Why? I think because it’s more in accordance with nature. That would also mean that Megan Fox, General Stanley McChrystal and Herschel Walker aren’t wrong, even if they think they sometimes think they are.

Diet experts, what are we missing?

To me it makes no sense to eat dinner at 6 pm, feel fatigued afterwards such that all I have energy for the rest of the night to do is watch TV in a horizontal position, then go to sleep around 10 or 11, just in time for my  food coma (apparently well known to researchers as as postprandial somnolence) to be wearing off. So pending and likely regardless of any arguments to the contrary, I think for the next month I’m going to push my first meal of the day, dinner, to 8 pm and see what that feels like.

As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.

Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.

4 thoughts on “Are Dietitians Wrong About Dinner Time?

  1. Chad,

    Interesting blog post.

    This article is an interesting combination of your view versus mine, as it backs up your point about being hungrier at 8pm, as well as drinking protein before falling asleep; but backs my supposition regarding the negative physiological effects of eating late. However, your late-at-night 2-4 hour eating windows wouldn’t apply here…or would they?

    https://www.washingtonpost.com/national/health-science/why-eating-late-at-night-may-be-particularly-bad-for-you-and-your-diet/2015/08/24/ad8b85ac-2583-11e5-b77f-eb13a215f593_story.html

    You will like this one, as it addresses how those who exercise may be able to avoid the negative physiological effects of night eating. Maybe why some females who are not exercising as a lifestyle gain when eating late on extremely short windows of intermittent fasting;

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4425165/

    Lastly, you did mention that those with acid reflux should not eat and go right to bed, but the first statement here mentions that GI function is reduced during sleep. If this means all GI function, not just the esophageal sphincter, then perhaps eating before going to sleep is not optimal?

    http://www.ncbi.nlm.nih.gov/pubmed/12184167

    • Hi Romy!

      Sorry it took me so long to post a reply. I started it but was working hard on my coracoidopathy blog, and lost momentum. Anyway here’s what I think.

      Regarding link one. I think the gal is towing the usual line about eating early being better. She cited a study that supposedly found greater weight loss with earlier meals, but when I read that paper it was only in relation to lunch time, while both breakfast and dinner not having a significant effect. Plus she went on about evening binges and night eating disorder and how evening calories are bad. I’m of the opinion that the evening is when people are most hungry, AND bored both of which are major triggers for binges. Those binges being particularly consequential if you already ate most or all of your daily allotment of calories during breakfast, lunch, and an early dinner. Night eating disorder in particular, I think would be particularly hard to do if you went to bed on big happy meal and were dreaming those calories away in postprandial somnolence bliss. She did mention the same study I did about people being hungriest at 8 pm, and (given a normal schedule) I think one’s eating window should include the 8 pm hour. I don’t consider that ‘late’ or such that it will disrupt circadian rhythms. Shift work and eating after midnight, would I think be another matter altogether.

      Paper two you link was interesting and I actually read that one a few weeks ago, and it (in addition to a number of others) was on my mind when I wrote my blog. I thought it interesting that they advocated a protein or carb meal before bed, but I don’t buy their reasoning that macronutrients shouldn’t be mixed. I think protein before bed, likely is anabolic, but I can’t imagine why carbs or fats would impede that, plus carbs and fats are supposed to be more likely to make you tired than is concentrated protein. I think they are onto something though, and I expect there are some confounders in the research, as well as some publication bias clouding reality. I agree exercise might be a factor, I’ve seen a few studies which when juxtaposed might lead me to that conclusion, but not enough to be sure.

      Paper three, I wish was in English because I would like to read more than the abstract. I think one has to cherry pick it to conclude GI function is reduced during sleep because though is says, “Salivation, swallowing rate, upper esophageal sphincter pressure and number of primary esophageal contractions have all been shown to be reduced during sleep,” those are all things that are important while eating, or going, not necessarily digesting. Later from the abstract I can pull the following quotes:

      “REM sleep is associated with faster gastric emptying.”

      “During the night we have a more regular intestinal motility…”

      That make me think certain parts of digestion are enhanced. Other parts mentioned about colon contractions seemed more in related to keeping one from having to go to the bathroom in their sleep, not necessarily in absorbing nutrients. And maybe it depends on what you are eating. Wilderbeasts eat a lot of low nutrient high fiber foods and can’t afford to sleep after a meal. Lions binge on wildebeests, which are high in nutrients and go to bed immediately.

      Oh, and I did try about a month of not eating till 8 pm and it resulted in an elevated BUN, which I’m not sure if it’s from too much protein, or too much protein in what was just a 1-2 hour window. It was making my evening productive however. So I went back to my usual 4 hour window. One night a week I don’t eat at all (I call it Tasteless Tuesday) making for a 44 hour fast. Instead of falling asleep around 10 pm, I’m up till 2 am. So I think the increased adrenaline with fasting is legit.

  2. I don’t appreciate the title of this blog. I don’t know any dietitians that say everyone should eat dinner at 6 pm.
    If you want to eat at 8 pm…go for it!. A big meal any time of day will probably make you sleepy. Many people have trouble eating breakfast because their bodies are not used to it, not because they shouldn’t eat breakfast.

    • Hi Karen, sorry about the title. It’s meant to be provocative. I’m not sure if dietitians say “everyone” should eat dinner at 6 but it sure seems a common suggestion. If I google the words “best time to eat dinner dietitian” I get several recommendations on the first page alone to eat an early and smaller dinner.

      Regarding eating breakfast when you aren’t hungry, I’m curious as to what you think of Krista Varady’s research on intermittent fasting. Here’s her answering questions about her research and 42:00 min into the talks about her lit review finding all the pro-breakfast studies were funded by cereal companies.

      I don’t recall all the pro-breakfast studies being industry funded but it was a lot of them. This interests me because of my intermittent fasting/time restricted feeding that I have been doing since April of 2015. There is some debate as to the best time to consume those calories, with me being of the opinion that earlier would be psychologically challenging. I know I have read a couple papers looking at eating times of day and one of the confounders they thought was important was morningness vs eveningness temperaments. Here’s one paper talking about breakfast and temperament that got me thinking about it. Here’s another where the researchers said “three meals plus snacks every day, is abnormal from an evolutionary perspective.” One of the reasons I skip breakfast, and lunch too, is to lessen my meal frequency. I’d love to hear more of your thoughts.

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