Sounds strange, right? (… or like a very promising approach) but when it comes to dieting we thought everything is based on the balance of calorie intake and the energy we spend. Well, that doesn’t seem to be the whole story. It is becoming clearer and clearer that another factor is involved in the equation for weight balance: Our biological rhythm. When do we eat and how often over the course of the day? And even more interestingly, sleep habits seem to play an important role in weight control.
In fact, several body functions are adjusted to the biological rhythm. The production of stomach acid, for instance, is characterized with low levels during the morning hours and high levels in the late evening. Intestinal movements have been shown to have time-dependent peaks and seem to easily adapt to individual habits or rituals (I’m sure the majority of us knows what time of the day they need to keep themselves close to a restroom…). All seems to be perfectly organized by Mother Nature, as always. But how come our bodies know what time it is? The most important control centre of several loop systems in our bodies is located in the bottom part of the brain, the hypophysis. It’s actually a gland releasing a variety of hormones regulating a wide range of essential functions, among others our food intake, by adapting to environmental factors. Primarily, the light-dark cycle stimulates this “master clock”, but also factors such as temperature, social habits and food are adjusting. These impulses are processed in the brain and transmitted to other body tissues, turning on so-called “clock genes”. As you might know, genes are located in every cell in our bodies and encode information for certain functions, such as these “clock genes” are involved in metabolic mechanisms like activating the break down and transport of dietary fats or other nutrients.
Sleep habits are highly involved in regulating our daily rhythms. Over the past decades sleep duration has gone back considerably, mostly due to lifestyle factors such as work conditions …for not bringing up regular weekends, you party animals!… let’s take the example of shift workers: This part of the population has in many studies been shown to have a higher risk of obesity and poor overall health conditions – researchers strongly suspect the link to lifestyle in this context: Has the biological rhythm gone out of order? In studies on rodents naturally active at night time reverse feeding at daylight hours resulted in significantly increased weight gain. Also manipulating the “code” of clock genes in mice could be linked to obesity. Up to now it is not known how a disbalanced bio-rhythm affects weight control, but there is rising consensus that it plays a role. Comparing different groups of workers, shift workers tend to have clear disadvantages with regard to their blood values. Whether this is due to the day-night rhythm could not be clarified yet as shift workers commonly also consume a diet high in fat… but why’s that? one might wonder. Sleep restriction has been associated with low leptin levels – a hormone that transmits the information “have had enough now” from our stomach to the brain. Too little of this hormone in turn would mean that we get hungry more often and sooner. Some studies suggest that this temporary effect might already occur after a total of 4 hours sleep restriction for 2 nights in a row.
Our lifestyles are depending on many different factors and some of them, especially the ones coming from work might be difficult to influence ourselves. However, we need to be aware of our biological rhythm and its impact on our food intake – and eventually weight control and the risk factors linked to it.
- Rest and routines: Aim for regular light exposure. I know, I know, winter is coming up so it’s gonna be challenging but worth a try. Get out there as often as possible, engage in regular exercise, and take your meals around the same times of the day. Habits help you to improve your sleep.
- Get your free regeneration boost! Most of the tissues and nerve cell reparation and renewal happens overnight, when we sleep – most effectively in our deep sleep phase (also essential when aiming to build muscles) Means: Sleep isn’t sleep. Try to eliminate as many sleep disturbing factors as possible. Stress, alcohol and heavy dinner may reduce the time of deep sleep thus decreases its positive effects.
- Early bird vs. night owl: Everyone of us has their individual demand of sleep. While one would still feel tired after 7 hours of sleep, others want to jump right out of bed after 6. Sleep demand can vary between 6-9 hours from person to person. Most people know what they need naturally but still don’t listen to their demands. Sleep has become a luxury good, so pay to it the attention it deserves!