A calorie is not just a calorie. It’s not just about what you eat, but also about when you eat. Mice are nocturnal creatures. They eat at night and sleep during the day. However, when mice are fed only during the day, they gain more weight compared to when they are fed a similar amount of calories at night. The same food and roughly the same amount of food can result in different weight outcomes, as you can see in the graph below and at 0:18 in my video.
Eating more calories in the morning to lose weight suggests that eating at the „wrong“ time can lead to disproportionate weight gain. For humans, eating at the wrong time would likely mean eating at night. Weight control recommendations often include advice to limit nighttime food consumption. This remained largely anecdotal until it was first experimentally investigated in 2013. Researchers instructed a group of young men to stop eating after 7:00 pm for two weeks. Compared to a control period where they continued their normal habits, they lost about two pounds after the nighttime eating restriction. This is not surprising, considering that dietary records show that the study participants accidentally consumed fewer calories during this time.
To see if timing impacts metabolism beyond just preventing eating opportunities, individuals would need to be forced to consume the same amount of the same food at different times of the day. The US Army took on such a study. In their initial set of experiments, Army researchers allowed people to eat one meal a day, either for breakfast or dinner. The results clearly showed that the breakfast group lost more weight, as you can see in the graph below and at 1:35 in my video. When participants ate only once a day for dinner, their weight did not change significantly, but when they ate only once a day for breakfast, they lost about two pounds per week.
Similar to the nighttime eating restriction study, this was to be expected as people tend to be hungrier in the evening. Think about it. If you didn’t eat for nine hours during the day, you would be starving, but people go through the night without eating for nine hours and don’t wake up ravenous. There is a natural circadian rhythm for hunger, which peaks around 8:00 pm and drops to its lowest value around 8:00 am, as you can see in the graph below and at 2:09 in my video.
Forced desynchrony protocol was used to discern the factors involved. Participants stayed in a windowless room with constant dim light and slept in staggered 20-hour cycles to completely disrupt normal sleep patterns. This lasted more than a week, allowing subjects to eat and sleep at different times throughout the day. Scientists could then determine if cyclical phenomena are truly based on internal clocks or just a result of what one is doing. Our body temperature, blood pressure, hormone production, digestion, immune activity, and almost everything else fluctuate daily. Given this, the concept of chronobiology, the timing of meals – when you eat – becomes crucial.
It’s wild, isn’t it? Two pounds of weight loss per week with the same amount of calories! This was quite an extreme study. What if you just shift a larger percentage of calories earlier in the day? That’s the topic of my next video: „Breakfast like a king, lunch like a prince, dinner like a beggar.“
Let’s take a break from chronobiology and explore the benefits of garlic in fighting cancer and colds. Be sure to check out the previous videos in the series in the related posts below. If you missed the first three videos in this series, be sure to check out the corresponding posts below!