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Don’t Eat at Night (What happens if you do) 10/13/10

October 13, 2010


Do you want eat oatmeal for dinner? Probably not.  Yet eating at night is biologically more unnatural than cereal for supper, and may expand your waistline even if you eat like a bird.   Ask the mice.

Mice are awfully cute if you don’t find them in your shoes when you wake up (it used to happen to me when I worked nights at Bellevue and tried to stealing an hour’s sleep in the on-call room. ) Where would human bioscience be without them?  Now the mice are telling us  that if we want to control weight, we shouldn’t  eat at night – and there’s considerable human data to back up that conclusion.


Night Eating and Weight Gain


Researchers at Ohio State and Israel wondered about what eating at night does to metabolism. They thought they might simulate humans keeping the TV on late at night in a group of  mice.  Since mice don’t pay much attention to television, they decided to place them under dim light or bright light throughout the period they normally sleep.  Would they still eat the same way?

Certainly not.  The mice gained a lot of weight.   The dim light group gained about 50% more than expected.  So the researchers cut their calories.  The mice still gained weight.  They gave them more exercise to do – still more weight gain.

Why?  Time rules life. Disrupt 24 hour clocks and lots of normal physiology unravels – that’s why we had Chernobyl and Three Mile Island turn into disaster at 4 AM. It’s not just judgement and cognition that goes out the window when animals are kept up during rest times.   Insulin levels, ghrelin, leptin, melatonin and other hormones change – though in the mice, steroid levels did not vary between groups.

So what’s happens to people?


Shift Work Means Weight Gain

1. In experiments done with US soldiers in the early 70’s, one meal a day was given – at breakfast, lunch or dinner.  The same meal, 2000 calories, and only once a day.  The morning eaters lost weight; the evening eaters gained weight.

2. Recent studies at the University of Surrey looked at shift workers and food intake.  Eating at night, not even early morning, was atherogenic – bad for your arteries.  Levels of lipids really went up when folks ate at night, far more than when they ate the same meal at normal times.

3. It’s been known a long time that shift workers gain weight; have more GI disease; have more hypertension; and get higher lipid levels.


What It All Means


Body clocks count.  Just as alcohol at midnight has 2-3 times the physiological effect of alcohol at 6 PM, a snickers bar at 9 AM is biologically different than the same bar at 1AM.

In the morning baseline insulin levels are high.  In the morning, food is metabolized more quickly and effectively.  Sugar and lipid levels don’t go up as fast.

Contrast that with early morning eating.  The glucose and insulin levels zoom far out of whack.  And the calories stay on you much longer – sometimes permanently.

Ask night eaters.  People who develop night eating disorders often gain much weight.


White Mice Rule the World?


When you eat may be as important as what you eat.  Perhaps Douglas Adams, the author of “The Hitchiker’s Guide to Galaxy” who died way too young, was telling us the truth – white mice do rule the world, doing experiment after experiment on humans.

And the mice are telling us something – try not eating at night.
Rest, sleep, Sarasota Sleep Doctor, well-being, regeneration, longevity, body clocks, insomnia, sleep disorders, the rest doctor, matthew edlund, the power of rest, the body clock, psychology today, huffington post, redbook, longboat key news



4 Comments leave one →
  1. October 13, 2010 3:26 PM

    Hi! So, when is too late? If I get home from Yoga at 7:30 and then cook and finish eating by 9:30. Then read and go to sleep around 10:30, is that too late or is that normal?

    • October 15, 2010 5:14 PM

      Sounds quite normal, except that most people finish eating earlier. If there’s no problem with your weight, I would not consider it a problem – particularly if you have a somewhat later body clock for eating.

  2. Robert permalink
    January 10, 2012 9:35 PM

    i get up round 2 in the day on holidays and have someting small for lunch a dinner and a cereal in the night which chould be elss then 2000 calories , dont understand how u cud gain more weight in the night then in the day , even though when im in college i get up round 7 have breakfast lunch and dinner , i just dont see the difference

    • January 13, 2012 8:34 AM

      Dear Robert,
      The reason is body clocks. Our body changes continuously throughout the 24 hour cycle. For example, alcohol at midnight will have 2-3 times the psychomotor effect as at 6 PM.
      Food changes, too – just like everything else (you can see my book “The Body Clock Advantage” for more detail.)

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