A Matter of Time


The next time you reach into the fridge for a midnight snack – take heed: New research by Weizmann Institute scientists has shown that the time at which you eat your meals might have a profound effect on your liver triglyceride levels. Their research was conducted on mice, but if found to be true for humans as well, it may have clinical implications in the way patients could be treated for fatty liver and other metabolic diseases, which are characterized by abnormally elevated levels of lipids in blood and liver cells.

fOur bodies are naturally cued to carry out various biological processes such as eating and sleeping at certain times of the day, and disruptions to this timing system, for example, eating at inappropriate times, may disturb the body’s natural rhythm and lead to disease. It’s no coincidence that shift-workers or those who travel frequently have been found to have a higher incidence as fatty liver and obesity, among other diseases.

Dr. Gad Asher of the Weizmann Institute’s Biological Chemistry Department researches the "biological clocks" known as circadian rhythms that are responsible for the fluctuating behavior of various biological processes. He and his colleagues have discovered that the levels of triglycerides – those nasty lipids that can build up in the liver and contribute to various heart problems – are regulated by these biological clocks, with their levels rising and falling according to a specific timetable. No big shocker there, but their next finding was quite surprising: When they restricted the mice’s meals to nighttime hours only, they saw a shift not only in the time the triglycerides had accumulated in the liver, but they observed a dramatic 50% decrease in overall levels. (And before you go ahead and open that fridge – remember: Mice are nocturnal animals so whatever works for them would be the opposite in us, humans.)

No drugs currently available for treating hyperlipidemia and hypertriglyceridemia – common diseases characterized by abnormally elevated levels of lipids in the blood and liver cells – have been shown to change lipid accumulation as efficiently and drastically as simply adjusting meal time. In other words, this research could lead to an alternative therapeutic intervention for such diseases:  simply adjusting mealtimes. As an added benefit, one would not have to suffer any of the side effects usually associated with the drugs.

Not only that, but the scientists say it could have  some farther-reaching implications. Just think about blood tests:  These are usually only carried out in the morning hours,  often after a fast. It is possible that the same test, carried out in the late afternoon, would yield different results? And the same holds true for animal researchers: Their data could  depend on the timing of samples or feeding schedules.

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And what is the case for humans who are basically nocturnal, or who are completely detached from the conventional clock and don't usually see daylight?

Both of those are norms in the culture of programmers and related engineering professions. Someone needs to study the time-related health variables in this sector of society, upon whom we depend for much of our modern infrastructure.

Other researchers do, indeed, look at the human cost (see above in the post). The above kind of study can find the exact biochemical mechanisms, which can then be applied to people. One of the problems with doing such studies in humans -- involving diet -- is in that you would not only have to take the timing into account, but to adjust for take-out pizza and coffee consumption. Clearly more research is needed, but ask yourself: How much of that programming really needs to get done at night?

It is very interesting how this plays out in the mice, but I have to question, how do other factors (like differences in circadian rhythms as G mentioned) have an effect on humans? It would also be useful and engaging to see how different individuals of varying gender and age groups would react to this study. According to the National Sleep Foundation, adolescents have a delay in their biological clock. As a teenager very interested in health and medicine, I would be curious to know the difference this age/circadian rhythm change causes on the liver triglyceride levels and how it would affect my meal times. Or if it would even make that big of a difference?

By Nicole Hedrick (not verified) on 09 Feb 2014 #permalink

Dr. Gad Asher replied: I do not have a good answer, in fact this is a very good question and future studies will hopefully provide an answer to these questions.
To date our studies are mostly limited to animal models which are well controlled.

If an optimum time was found that the biological processes are occurring within the animal could you therefore have more control on obesity and heart disease that occur and possibly limit the animal to these? Also if studied on humans would this have the same effect?

Studies would have to be carried out on humans, of course.

This is very interesting. It has never occurred to me that time can play a major role based on our biological factors. I have noticed that if I come home from a long, busy day without eating during my usual time, a disturbance in my body when I eat my "midnight dinner." I notice that I feel a little different (not by a whole lot) and it becomes harder to sleep at night right after I eat. But why does a change in your biological clock make sure a huge different later down the road on your body. For example, when someone moves to a new place over seas and they have to adjust to the time zone there, can this cause my problems down the road when they have to fully adjust to this for possible the rest of their lives? Do you think it affects younger people more, the same, or less than someone who is older? Also, based on what you eat at night I presume plays a role in how much or how little it can effect your body. Since our bodies have a nature way of healing ourselves, like forming scabes after cuts and getting better after a cold- because our homeosstatesis plays a role, it could be possible that if a person where to remain stable with a constant time on sleeping, eating etc. that the diseases possibly caused from this down the road can be "re-winded?" Do you think this can play a role in cancer also?
Diseases that can be caused from a disturbance does make sense because our bodies are like a machine and if the machine is not treated properly with care and maintenance the time of the machine will not work long.

I found this article very interesting. The title caught my eye but I didn't expect this is what the article would be on. I am very interested in weight loss and weight management and have done some research on it before based on past experience and other peoples experiences. I have heard from people that late night cravings and snacking is bad for you but never found an article based on it like this one. This makes me rethink the next time I want a snack before bed. It makes me curious how Dr Asher thought to study the circadian rhythm to see how our trygluceride levels are effected. It is interesting to think that we could find the cure to beat obestiy and heart diseases that has been effected Americans for years. When could they start doing these types of testing on humans since they have only been testing mice? And what kind of an effect do you think this kind of testing would have on humans?

By Emily Strogen (not verified) on 11 Feb 2014 #permalink

I found this article to be very interesting but it's not exactly new information. It's common knowledge to not eat after a certain time to benefit a healthy weight just like it is common knowledge not to eat McDonalds when dieting. However, I think it needs to become more known just how much the late night eating can set people back when trying to maintain a healthy diet. I would be curious to know if this pertains to all "midnight snacking" or if there are certain foods that will not disturb our biological clocks. Say you eat celery at one a.m. Celery does not have much nutritional value so will that throw our clocks out of wack as well. I realize it will not have the same effect as eating a burger at this same time but my question still stands if it is ok to eat late at night if it is something healthy.

Again, the study was done on mice -- it won't tell you what a human can eat at night. The surprise was not that our eating has a biological clock function, but that there is another clock, on top of the first one, that strongly regulates lipid storage in the liver.

I found this article to be very interesting and relatable! I constantly try to watch what I eat. We always seem to get hungry when we shouldn't get hungry. Like we want what we can't have. I've read other articles by Dr. Asher where he is talking about the biological clock. This tells us whether we should wake up, if it's time to go to bed, etc. This helps you decide when it may be "too late" to eat. I'm interested to see what happens to those who may work all night and work all day., or are just nocturnal. I think that it is cool that we are able to use mice as experiments before we use humans. Are there other animals that we could use to experiment on? I think this is interesting because everyone of us can relate to us whether we like to watch what we eat or we don't have a care in the world! Either way these experiments are working closer to reduce the amount of heart disease and obesity!

By Bethany ONeal (not verified) on 12 Feb 2014 #permalink