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Is When You Eat as Important as What You Eat?



Recently, a number of studies have looked at the impact of sleep deprivation, disruption of the sleep-wake cycle, and shifts in circadian rhythm on feeding behaviour and propensity to gain weight (facit: they are all bad!).

This is probably because, a complex biological clock machinery translates time information into physiologically meaningful signals by the regulation of hundreds of clock-controlled output genes (CCGs) that control virtually all aspects of cellular function.

From an evolutionary perspective this makes a lot of sense as certainly bodily functions make sense in the wake state but are not required whilst asleep, while other functions are best managed during night time, when the organism should normally be asleep.

Now there is work emerging that some of these metabolic changes can be reset or readjusted by the timing of food intake.

One such study is the one by Barclay and colleagues form the Max Planck Institute of Biophysical Chemistry, Göttingen, Germany, just published in PLoS One.

Based on the emerging body of evidence that shiftwork is associated with adverse metabolic pathophysiology potentially involving direct physiological effects of nocturnal light exposure, or indirect consequences of perturbed endogenous circadian clocks, the researchers used a two-week paradigm in mice to model the early molecular and physiological effects of shiftwork.

During this time, animals were kept awake during their regular sleeping hours and were provided foods either during their normal waking hours or their ‘night shifts’.

According to their findings although the two weeks of timed sleep restriction had rather modest effects on diurnal activity patterns, feeding behavior, and clock gene regulation in the circadian pacemaker of the suprachiasmatic nucleus, microarray analyses revealed considerable global disruption of diurnal liver transcriptome rhythms, enriched for pathways involved in glucose and lipid metabolism.

Much of these metabolic abnormalities were prevented by restricting food intake during the ‘night shift’ and providing access to foods only during the beginning of ‘normal’ waking hours.

Thus, the authors conclude that,

“Although altered food timing itself is not sufficient to provoke these effects, stabilizing peripheral clocks by timed food access can restore molecular rhythms and metabolic function under sleep restriction conditions.”

They thus further speculate that,

“…strengthening the peripheral circadian system by minimizing food intake during night shifts may counteract the adverse physiological consequences frequently observed in human shift workers”.

Obviously, these findings need to be replicated in human shift worker. I, for one, can certainly attest to the fact that the notion of not eating during long night shifts may well prove a challenge for most people (particularly during the wee hours of the morning when cravings for sweets and junk food seem the hardest to resist). On the other hand, I do recall that the nights, where I had a normal dinner prior to starting a shift were less problematic than taking a midnight or early morning break for a meal.

I would certainly love to hear from readers about their experiences with eating and weight gain during shift work and how they deal with shifting sleep wake cycles.

AMS
Red Deer, Alberta

ResearchBlogging.orgBarclay JL, Husse J, Bode B, Naujokat N, Meyer-Kovac J, Schmid SM, Lehnert H, & Oster H (2012). Circadian desynchrony promotes metabolic disruption in a mouse model of shiftwork. PloS one, 7 (5) PMID: 22629359

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3 Comments

  1. This is a problem for me with constant travel. Frequent fliers often gain weight.
    I travel with food, and try to shift approx 1 hr/day on my normal (7a, 1130a, 530p) meal cycle. I travel with my food, especially my breakfast which is the same EVERY day (oatmeal, dried skim milk, whey and casein protein, dried unsweetened fruit, cinnamon, and cocoa).
    Some posts on these issues: http://www.howilost100lbs.com/?s=%22jet+lag%22

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  2. I went through a long period of night sifts when I was a grad student and post doc in particle physics in the early 80s. Our shifts were 12 hours a day – seven days a week when we had “beam” and five days a week otherwise. The longest run I went through was 14 months with one week off … otherwise it was solid work time. At the time I was young and, as a runner, light for my height – 145 to 150 pounds and 6’1.

    I found it impossible to fight food cravings and pretty much lived off of junk food throughout the night – potato chips. m&ms and ice cream sandwiches – I’d hate to think about my cholesterol levels back then. I would “crash” from 3 to 5am each morning – I’d still try to be working, but would be very inefficient and my body temperature seemed to drop (although I never measured it). I had to keep a sweater around to stay warm even when it was in the high 70s.

    I didn’t gain or lose weight, but I also had very little appetite when I wasn’t working. For that period I was getting by with about five hours a sleep a day. All in all terribly unhealthy.

    Since then I got married and slowly gained weight as my exercise routine went away. I wasn’t working night shifts anymore, but I did get up to about 220 pounds. A few years ago I decided to lose weight and am now in about 155 and have been holding steady for a few years, but it takes considerable effort and focus (much more difficult than losing the weight in the first place) with daily journaling and measurement. Left to my own devices I would probably gain what I lost.

    But the night shifts were very disruptive. I did try fasting a few times to see if that would help, but the urges for junk food and the big bowls of free m&m’s and chips proved too much for my limited willpower.

    We did have another grad student who was more sedentary than me on the same shift and he gained a huge amount of weight despite being in his early 20s and slim before the run. He never lost the weight afterwards. I’ve never seen anyone gain weight so quickly. He became alarmed and started calorie counting sticking with the recommended number and then dropping that by a few hundred calories a day, but the weight gain continued.

    The folklore from techs who had been doing this for multiple decades was that there were two types of people – those who lost and those who gained – no one stayed the same.

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  3. I’m not a shift worker but I do stay up till 1 or 2 am in the morning . I get hungry after dinner about 9-10-11 pm and snack .I’m not working now so I can sleep late..this is a lifetime habit of staying up late .I don’t snack during the day but at night I go crazy.

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