Does when you eat matter?

Everyone has an internal clock, called the circadian rhythm, that controls wake/sleep cycles, body temperatures, brain activity, and changes in hormone levels throughout the day.  Disruption in these circadian rhythms can alter metabolism.  In the latest issue of Cell Metabolism (epub ahead of print June  2012 DOI 10.1016/j.cmet.2012.04.019), Dr. Megumi Hatori and colleagues investigated how feeding patterns, in particular time restrictions to eating, can alter metabolism and the expression of genes that control the circadian rhythm.  

Mice were divided into four groups as follows:

1. Normal calorie diet, freely accessible all day
2. Normal calorie diet, limited access
3. High fat diet, freely accessible all day
4. High fat diet, limited access

Mice are nocturnal and were placed on a 12 hour light/dark cycle.  For groups 2 and 4, food was available from 1 hour after lights off (waking) until 3 hours before lights on (sleeping).  

Their data were intriguing.  Mice in both high fat diet groups consumed equivalent numbers of calories over a 24 hour period.  Those with free access appeared to eat all day with no spike in intake at any regular time period, while those with limited access consumed their calories only during the 8 hour period.  

As expected, mice with unlimited access to the high fat diet gained significant weight compared with either of the normal calorie diet groups.  Conversely, the mice on the high fat diet with limited access did not have the same weight gain as the unlimited access group.  Indeed, mice in the time restricted groups were lower weight than those with unlimited access.  When comparing the high fat diet groups, the mice with limited food access did not become obese as did the unlimited access mice. In fact, their weight was only slightly higher than the normal calorie diet groups.  In addition, the time restricted high fat diet group also retained sensitivity to insulin and did not exhibit liver problems as seen in the unlimited high fat diet group.

This very interesting study suggests that circadian rhythms control metabolism and restricting food intake to regimented periods during the day can help to keep the metabolism strong and avoid excessive weight gain.  This is a small study in mice, but could have implications in human dieting and the control of weight gain.

Science for the public

by Jasper Manning, Ph.D.

Each day large amounts of scientific information is disseminated from mass media to the general public. This includes healthy-related studies and novel scientific breakthroughs with the aim of educating, informing and improving the quality of life. Much of this information comes from pundits and medical reporters who support their ideas with well researched facts. However, in some instances, facts are misconstrued in order to support a specific agenda(s) of a political lobby or industry i.e. global warming or endangered species lists. In addition, the summary of published information by medical writers sometimes is erroneous due to lack of available print space and/or time set aside for an article or misinterpreted perhaps due to a lack of knowledge about a topic. In the end, an article that is unable to convey to laypersons the benefits or detriments of a study defeats the intended purpose of the article. Howy Jacobs, a distinguished professor of molecular biology at the Institute of Medical Technology (IMT), University of Tampere and senior editor at EMBO Reports recently suggested that a miseducation of the masses through mass media is due to the misconnection between science and the media (Jacobs, 2012) and believes that the responsibility of educating medical writers falls on scientists. Once this can occur, the reader, has a better chance of receiving complete and concise information. 

Jacobs illustrates the lack of clearly presented information to the general population by relating a recent conversation that he had with a southern Alaskan Bed and Breakfast owner. The owner espoused that climate change was not a reality and had no affect on wildlife specifically in the case of the polar bear. Jacobs notes that after some fact-checking, he found published data of comparative mitochondrial DNA sequence of polar bears and brown bears that supported that environmental stress (Edwards, et al, 2011) may have influenced a recent introgression between the two species. Dr. Jacobs chose not to challenge the beliefs of the owner (perhaps many scientist choose to sit out these arguments), but realized that the scientific data is available although public awareness is lacking. This is a plus for lobbying groups and others since a uninformed public can be easily influenced by those who have a vested interest in exploiting the environment. He astutely points out that science should not support political argument/agenda, nor “prove” a hypothesis but accumulate, interpret data and form a predictive model based on the interpretation. In his opinion, the media should explain this process used by scientists and report the findings legibly or risk painting a picture of science as a confusing and perhaps dishonest profession as in the case of global warming.

 All in all, the take home message of the Jacob's editorial is that scientists must be able to better convey scientific results to the media in a clear and comprehensible way. On the other side of the coin, the media has a responsibility to become more knowledgeable in basic science and the aspects of the scientific method. He believes that miscommunication is the primary problem and scientist must learn to better explain interpreted data to the world and correct poorly presented interpretations that are published in the media.

 It is refreshing that scientists such as Howy Jacobs understands that scientist are the key to explaining the latest breakthroughs and correcting errors in summarized studies that are published in the public domain. Blogs such as N3science communications is a good starting point as well. Take a read and pass it along. Scientists are trying to educate, now it is your turn to read and understand what is happening with science around you.

 REFERENCES Howy Jacobs EMBO reports (2012) 13, 471;doi:10.1038/embor.2012.56 Edwards CJ et al 2011) Curr Biol 21:1251-1258