Should You Avoid Eating At Night?

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Should You Avoid Eating at Night?

I hate to be the bearer of bad news, but maybe there are good reasons to avoid eating at night. (I’m not talking about the old myth that says that anything you eat past 6 p.m. just magically turns into fat). I know that this is going to directly contradict and probably upset a lot of current popular diets and diet experts…and I’m okay with that.  I don’t write to make friends; I just enjoy reading about training and passing some useful information on.

The first group of people who will probably cry about this are the science guys who disregard everything that suggests that there might be more to dieting than the energy balance of calories-in vs. calories-out. Shortly after the calorie guys, however, come the “it’s all about the macros, bro” guys. If only the human body was as simple as those in the fitness industry makes it seem. I am not debating the importance of your caloric balance and your macronutrient/micronutrient intake, but there’s some really interesting research regarding our body’s circadian rhythm, which may make nutrient timing even more important.

Circadian Rhythm 

This brings me back to my days as an overly tired student trying to escape my neuroscience classes. Our master clock, or biological clock, is a small part of the brain referred to as the suprachiasmic nucleus (SCN). This clock helps to keep your body on schedule so to speak.  The body follows “circadian rhythms”, primarily in response to light/darkness and these rhythms have an effect on almost all physiological processes.

Basically, your body has a schedule that it likes to follow everyday.  Based off this 24 hour schedule, you will release certain hormones during specific time periods.  An example is releasing testosterone and cortisol in the morning to promote alertness or secreting melatonin at night to promote sleep.  It does this by following cues from our external environment, like the time of day.

There are also peripheral clocks throughout the body which keep tabs on energy status. So, in order to make sure these “systems” are operating properly, our bodies should have periods of low food intake—and this should be in sync with our nighttime or inactive phase.  Feeding during the inactive phase is associated with a host of undesirable things like increased body fat, glucose intolerance, and inflammatory disease.

Time-Restricted Feeding

The first study I want to share was a study done on mice called, “Time-Restricted feeding without reducing caloric intake prevents metabolic diseases in mice fed high fat diet.”  In this study, the researchers were trying to determine if obesity results from a high fat diet or from a disruption of metabolic cycles, namely circadian  rhythms.

There were two groups of mice. One group had a feeding window that was time restricted to eight hours (tRF) and the other ate ad libitum (whenever they wanted). (Calories were the same and from a high fat diet in both groups). The time-restricted mice were protected against obesity, hyperinsulinemia, inflammation, and had improved motor coordination, glucose tolerance [1]. They also experienced improved oscillations of the circadian clock, improved nutrient utilization, and improved energy expenditure [1].  Here’s a picture from the study.

eating at night

If you are wondering why the cheese on the right is over the moon it’s because mice have an opposite circadian rhythm for activity than humans do, so nighttime is actually their “active phase”. It makes sense that we do not want to eat much during our inactive phase. If we consistently eat during our inactive phase (at night), it will cause our peripheral clocks to be out of sync with the master clock in our brain.

Another interesting study shows that not only when we eat matters, but that the macronutrient consumption during specific times matters as well. The study, “Time-of-Day-Dependent Dietary Fat Consumption Influences Multiple Cardiometabolic Syndrome Parameters in Mice,” made some very intriguing points.

Here were some of the most interesting quotes from the study:

  1. “Mice fed a high fat meal at the beginning of the active period retain metabolic flexibility in response to dietary challenges later in the active period.”
  2. “Conversely, consumption of high fat meal at the end of the active phase leads to increased weight gain, adiposity, glucose intolerance, hyperinsulinemia, hypertriglyceridemia, and hyperleptinemia (i.e., cardiometabolic syndrome). The latter perturbations in energy/metabolic homeostasis are independent of daily total or fat-derived calories.”
  3. “We report that high fat feeding at the transition from sleeping to waking appears to be critically important in enabling metabolic flexibility and adaptation to high carbohydrate meals presented at later time points. Conversely, high carbohydrate feeding at the beginning of the waking period dramatically impairs the metabolic plasticity required for responding appropriately to high fat meals presented at the end of the waking period.”
  4. “… A high carbohydrate morning meal appears to “fix” metabolism toward carbohydrate utilization and impair the ability to adjust metabolism toward fat utilization later in the waking period.”

These points all make sense. A high fat breakfast seems to set the body towards higher fat oxidation, whereas high carbohydrates in the morning set the stage for carb oxidation as opposed to fat oxidation. We want to maintain metabolic flexibility so that we can use our body’s stored fat as fuel during the appropriate times. There are a plethora of benefits to having periods where insulin is low, as I have mentioned in earlier article’s and a carbless breakfast or no breakfast helps keep insulin levels below. I wrote on an anabolic breakfast (Read Here) which also presented some research as to why it may be beneficial to avoid carbohydrates at breakfast.

Nighttime Eating

nightfood

So, should you avoid all food at night? No, that would be awful but maybe you should limit some things. Despite what you have heard about nighttime carbohydrate consumption, it is not bad. However, fat intake at night does seem to have some negative consequences. In the study “Greater Weight Loss and Hormonal Changes After 6 month Diet with Carbohydrates Eaten Mostly at Dinner,” Israeli Police officers were split between having the majority of their carbohydrates in the morning vs. at night. It’s not the most intelligently laid out study, but the results clearly show that the nighttime carb eaters dropped more percent body fat, were more satiated, increased insulin sensitivity, had higher leptin, and improved blood glucose levels. [3] Those that preach carbohydrates at breakfast counter with, “but insulin sensitivity is highest in the morning.” This is true, but it’s for muscle and fat cells. So it’s kind of a moot point.

Understanding the importance of our circadian clock goes beyond physique enhancement. A study presented in the Endocrine Review, “Metabolism and Circadian Rhythm-Implications for Obesity,” offers a very in-depth look at the intricacy of our circadian clock and the various roles it plays in our body. In their conclusion they state, “Western lifestyle leads to high food consumption, inactivity during the active period, enhanced activity in the rest period, and shortened sleep period. This lifestyle may cause high parasympathetic output to the viscera leading to obesity, hyperinsulinemia, and hyperlipidemia, or high sympathetic output to the muscle and heart leading to vasoconstriction and hypertension. Indeed, disrupted biological rhythms might lead to attenuated circadian feeding rhythms, disrupted metabolism, cancer proneness, and reduced life expectancy.” [4]

There is too much research to not accept that food timing absolutely does matter. Why? Because our circadian rhythm regulates energy homeostasis, and our type and timing of food has a direct effect on our circadian rhythm.

So, here are some tips on how to use this information in your diet:

  • Carbohydrates are not necessary at breakfast. Instead, opt for a protein/fat breakfast or fast during this time. If fasting, make sure that you are consuming water as dehydration will take away from some of the beneficial fasting effects.
  • Watch your fat intake and calorie intake at night or during your “inactive” phase.
  • You do not need to eat all day long, and you definitely don’t need to eat every two to three hours. Let your body shift between its natural anabolic and catabolic processes which leads to improved health in the long term.
  • Intermittent Fasting can be used to improve circadian rhythms, decrease body fat and has plenty of longevity and anti-aging effects that I discuss this in my book

    .

  • If you are more concerned with the health aspect of fitness and maximized fat loss, then look into fasting and restricted feeding windows.

References:

[1] Time-Restricted Feeding without Reducing Caloric Intake Prevents Metabolic Diseasesin Mice Fed a High-Fat Diet.  http://ac.els-cdn.com/S1550413112001891/1-s2.0-S1550413112001891-main.pdf?_tid=c750109e-f49c-11e2-ae2a 00000aab0f27&acdnat=1374696677_72ab1ee995d0238c698cdcd2cbc37d26

[2] Time-of-Day-Dependent Dietary Fat Consumption Influences Multiple Cardiometabolic Syndrome Parameters in Mice. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3021134/

[3] Greater Weight Loss and Hormonal Changes After 6 Month Diet with Carbohydrates Eaten Mostly At Dinner.  http://www.sciencedaily.com/releases/2012/11/121111153640.htm

[4] Metabolism and Circadian Rhythms—Implications for Obesity. http://edrv.endojournals.org/content/31/1/1.long

7 Responses to “Should You Avoid Eating At Night?”

  1. Simon

    Interesting article, just a few questions, mainly about the active and inactive window, and protein intake.

    1stly a bit about me, I tend to intermittently fast with a larger feeding window on the days i work out, as i work out in the morning around 9.30am and normally have some whey before and after i work out. work out 3 times a weeks doing full body workout, i try to do a few sprints a week fasted.

    Right so with the inactive/active window, i often do evening classes and as my job involves mainly sitting at my desk it would be fair to say my active window extends into the evening? I tend to eat before and after the class so at 6.00pm and 9.00pm, although this is late Ive always thought it would be ok as I’m just refilling glycogen and getting some protein in the 9.00pm meal. On days i don’t have an evening class i eat about 7.00pm and maybe have a snack later. Does this seem ok to you?

    Lastly i have always tended to have a whey+casien shake before about an hour before i go to bed, so i have protein in me as i sleep, this would be about 10.00pm, do you think this is a bad idea? I guess im trying to make sure i have adequate protein over the whole day and although i appreciate protein doesn’t digest too fast i don’t want too long a fasting (from protein window) as it seems to me after 10+hours most of the protein in my food would have been digested.

    any thoughts on what i have said? am i wrong in any of my assumptions?

    a reply would be welcome.

    Simon

    Reply
    • Fred Duncan

      Simon, Thanks for reading.

      First thing, Your active/inactive phase is also dictated by lightness/darkness, not just your energy level. For example, when it’s light out the body will limit the release of melatonin whereas it’s increased due to darkness. However, the research in the article makes the case to watch fat intake at night, not necessary all food intake. Your protein/carbohydrate meals at night are just fine, especially if you need to make up for missed calories from earlier in the day.

      You could potentially eat all of your calories at night and make it “work”. Your daily/weekly caloric intake and macronutrient levels will still be the most important aspect in achieving your goals.

      In terms of not wanting a long “fast” period I’d have to disagree. The human body is extremely complex and does not need protein every 2-3 hours to maintain tissue. There are a host of mechanisms that actually protect muscle during longer fasts. Your body appreciates some time of no food intake as it initiates a process called autophagy which is a cellular degradation process where debris and unused proteins of the cells are “cleaned” up. During this time your body can also work on breaking up the uneeded tissue (fat) and using it for energy as there is no incoming food/fuel to rely on.

      Fasting is very misunderstood because too many people fail to recognize what is happening at the micro level. I’m in the process of writing a book on fasting and how I use it with my clients to lose fat, build muscle or recomp their physique. I will be going very in depth and exploring all of the mechanisms in play during fasts or periods of catabolism. If you are interested in fasting, it’s benefits and how to use it to change your physique you may want to check it out once I’m done.

      Thanks for stopping by the site!

      Fred

      Reply
      • Simon

        Thanks for the prompt response. The melatonin thing is not something I considered, but i see your point. The protein/carb meal in the evening normally consists of tinned salmon and potatoes maybe a bit of cheese. Thinkin about is that may contain a fair bit of fat… do you think thats too much fat? I tend to eat it cos its easy, and full of good quality protein.

        I do tend to like fasting, and i understand it does protect against muscle protein degradation, but im not conviced it is ideal for synthesis. My carb/fat fast tends to be 14-16 hours, my protein fast tends to be 11 hours on a day im working out and 13 hours on a non work out day. Not sure if thats ideal, i guess what i should have said is although i could drop a little body fat i am fairly lean, my abs just about show, my main goal is gaining muscle mass and strength, with the minor goal to loose a little fat or at worst just not put any on. If i was trying to loose fat primarily i would definitely fast for longer.

        I will say my mind isnt made up, I can see a range of fasting benefits which i would defenitetely recomend for anyone who doesnt work out, i still have this doubt that it can really be ideal for gaining muscle, especially if you are like me and started out quite skinny and therefore reach the point where it is hard to put on more muscle sooner than other people.

        Again thanks for the response

        ps. ive read most of your site, and have it on my rss feed.

        Simon

        Reply
        • Fred Duncan

          Simon, I’m glad you like the information on the site. I will continue to keep it updated.

          In terms of fasting for muscle building, or if it’s beneficial for protein synthesis, I’ll say this much. There are many ways to incorporate fasting into your routine. I’ve used it with clients for muscle gain or fat loss. I simply view fasting as a tool. The more tools you have, the more novelty you can continue to present to the body. It’s certainly not the only way to diet but I’ve found that it really helps keep body fat in check which optimizes your nutrient repartitioning.

          I’m going to cover all of this in my upcoming project and I’ll discuss a style of eating I’ve had tremendous success with for recomping one’s physique.

          Reply

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