Given the effectiveness of chronotherapy – how the same dose of the same medication taken at a different time of day can have different effects – it is not surprising that approaches to chronoprevention, such as timing meals, can also make a difference. The 2017 Nobel Prize in Medicine was awarded for the „elucidation of the molecular mechanisms of the circadian clock,“ our internal clock. Life on Earth evolved over billions of years to a 24-hour cycle of light and darkness, so it’s no surprise that our bodies are precisely tuned to this pattern. Even in total darkness without external time signals, our body continues to operate in a circadian rhythm of about 24 hours.
You can even take tissue biopsies from people and show that cells continue to circulate in a petri dish outside of the body. Nearly every tissue and organ in our body has an internal clock. A complex system of intrinsic clocks controls not only some of our behavioral patterns like eating, fasting, sleeping, and wakefulness, but also our internal physiology – our „body temperature, blood pressure, hormone production, digestion, and immune activity.“ Most genes in our body „exhibit daily fluctuations in expression levels, making circadian gene expression rhythms the largest known regulatory network in normal physiology,“ the largest regulatory system in our bodies.
It is believed that this cycle allows for a certain level of „predictability“ and „functional partitioning,“ enabling each of our body processes to occur at the best time. For example, at night while we sleep, a whole host of internal housekeeping activities can be turned on, and as dusk approaches, our body can switch back into activity mode. Anyone who has suffered from jet lag knows what it can do to delay their cycle by just a few hours, but now we know that our circadian rhythm can determine life and death.
A study of more than 14,000 cases of self-poisoning found that those who attempted suicide in the morning were more than twice as likely to die as those who took the same dose in the evening. Similarly, timely chemotherapy can not only be five times less toxic, but also twice as effective against cancer. The same medications, in the same dose, but with different effects depending on the time of intake. Our body absorbs, distributes, metabolizes, and excretes what we consume differently depending on when in the 24-hour cycle, as you can see below and at 2:19 in my video Chronobiology: How Circadian Rhythms Can Control Your Health and Weight.
We are only just beginning to determine the optimal timing for various medications. If chronotherapy – the optimal timing of taking medications – can have such an effect, it should perhaps not be surprising that chronoprevention – planning lifestyle interventions like meal times – can also make a difference. In the official position paper of the Academy of Nutrition and Dietetics on effective treatments for obesity, emphasis is placed not only on the amount, but also on the timing of calorie intake. „Potentially expending more energy [calories] earlier in the day rather than later in the day may be beneficial in weight control.“ Some have gone even further and have labeled obesity as a „chronobiological disease.“
The evidence for these kinds of claims? Well, the „timing of energy [caloric] and nutrient intake has shifted over time, with the proportion of intake later in the day increasing,“ which raises the question of a possible role in the rise of obesity. Middle-aged men and women who consume a larger portion of their daily calories in the morning seem to gain less weight over time, and a study titled „Time of meal intake predicts weight loss effectiveness“ found that dieters who consumed their main meal earlier in the day steadily lost more weight than those who consumed their main meal later in the day, as you can see in the chart below and at 4:12 in my video.
The apparent explanation for these findings would be simple, that those who eat later also tend to eat more. Indeed, there seems to be a connection between the time people consume most of their calories and the total amount of calories they consume at the end of the day, with those who consume a larger portion in the morning eating less overall. Maybe later eaters indulge in too much junk food on the couch while watching primetime TV? Night owls have been found to consume more fast food and soda, as well as less fruits and vegetables.
In the field of social psychology, there is a controversial concept called „ego depletion“ where self-control is considered a limited resource, like a muscle that can fatigue from overuse. Throughout the day, the ability to resist unhealthy eating may wane, making one more susceptible to temptations. So is it just that later eating leads to more eating? In the aforementioned study where early eaters steadily lost more weight, to the surprise of the researchers, early eaters consumed just as much as late eaters, despite the difference in the extent of weight loss. At the end of the 20-week study, early eaters were about five pounds lighter than late eaters, even though both groups ate the same amount of food. There seemed to be no difference in physical activity between the two groups. Could it be that the timing of calorie intake alone plays a role? Scientists decided to put it to the test, which we’ll discuss next.
Wasn’t that chemo data wild? If you’re taking blood pressure medication, please share this video with your doctor and ask if your timing is optimized. We started this series on chronobiology with a look at the importance of breakfast for weight loss. In case you missed those videos, check them out here. For more on this topic, check out the related posts below.