Rhonda: You've also found that people follow, generally speaking, an eating pattern, like if they're not trying to eat within a certain time window, with your My Circadian Clock app, you found naturally people eat within a longer window than they thought they would eat. Is that correct?

Satchin: Yes. So when we started these mouse studies, then we realized that we're kind of adding another leg to human nutrition research. That is we know that the number of calories and the type of food that we eat have a huge impact on our health. And we just started when we eat is also important, that it becomes an important issue to understand when people eat because we do have different methods, for example, 24 hours dietary recall to understand how much and what type of food people ate in the last 24 hours. Similarly, there are methods to measure what diversity of four people have eaten in the last three months or a year to a tool called food frequency questionnaire or FFQ. But there is no method to really understand when people eat. We can ask people, "When did you eat breakfast? When did you eat lunch, dinner?" but that doesn't give us the correct view because we often ignore the occasional eating or snacking that we might have done late at night or early in the morning. And we consider them to be benign and we don't report them. But as I mentioned, even one gram of sugar can change my blood sugar level, so we wanted to capture every single eating event that happens. And from circadian rhythm point of view, even if you ate or drank something that has calories maybe two to three hours after your dinner time just for one day in a week, that can have an impact on your circadian rhythm for two to three days. So even if people eat outside that usual dinner time or breakfast time for one or two days in a week, they might ignore it and may not respond to questions. But if we can capture that, then we objectively know their eating patterns. So that's why we started this app called My Circadian Clock. People anywhere in the world can go to the website, sign up for the study. It's an academic study. There is no commercial interest here. And they share their data with us. What we found is nearly 50% of adults have an eating window of 15 hours or longer. So that means in a given week, there is a 95% chance that they would eat within that 15 hours window. That means that if somebody wakes up around 6:00 and has a cup of coffee with cream and sugar, a little bit of sugar immediately after waking up, then this person is also going to bed, say, at 9:00 or 10:00 at night and is having a glass of milk or beer or something else that has some calories, then that is roughly 15 hours of eating window. And even if this person does this only a couple of times in a week, still the circadian system is anticipating that that's the eating window. So that way, we develop this app to measure when people eat, in addition to the tried and tested methods of what and how much we eat. And we figured out that nearly 50% of adults eat for 15 hours or longer, and only 10% of adults actually eat for 12 hours or less interval in a day.

Rhonda: And what percentage of people think they eat for 12 hours or less if you ask them without...?

Satchin: That's almost 100% because in this first study, when I did the study on 156 people, we had a questionnaire where we asked them, "What time do you eat your breakfast, lunch, and dinner? What is the interval of time when you eat?" and when we compare their own response, it was only less than 5% of people who said that they eat for more than 13 hours. So what we perceive how we eat and how we actually eat is very different. And all of you, listeners, if you just think back and ask yourself is there any day in the last seven days when you had a piece of cookie, or a glass of beer, or wine a couple of hours after your dinner time, after your dinner was finished, I guess that at least half of you would remember at least one day in the last one week you had done that. And this is almost like your body flying to a different time zone and coming back from the circadian point of view. So that's why when we think of when we eat, it also brings up other aspects of the timing. And since the research is very new, it will have more variations to the timing. People will start thinking, "Okay, what happens if you eat after an hour of waking up versus six hours after waking up? What happens if you eat only 2 meals in a day versus six meals within that 8 hours or 10 hours?" So all of these variations of human nutrition timing are yet to be fully studied. But I'm glad that our research has put focus onto this timing of food as a variable impact.

Rhonda: Is it better to have an eating window that if, let's say, you're eating within an 8-hour time window, I guess, you're not eating for 16 hours? Is it better to have that eating window end at 7:00 p.m. versus, let's say, 11:00 p.m.?

Satchin: So this is where biology, and our human behavior, and personal choices come into play. For most of us, what we see from the app data is there is a circadian pattern or the time of the day pattern to what people typically eat. For example, if you ask what time of the day people are more likely to drink alcohol and have more sugary treat, it's between 7:00 p.m. and 11:00 p.m., or midnight. So then, if you're eating alone, and if you have complete control over your diet, and you have this very strict diet regimen, what you want to eat, then it doesn't matter whether you are finishing dinner at 7:00 p.m. versus 11:00 p.m. But if you target that you are ending that 8 or 10 hours window at 11:00 p.m., and that includes socializing with other people and sharing food, or being even influenced by what other people ordered for dinner, then you're likely to consume a lot of unhealthy food during that extra...between that 7:00 p.m. and 11:00 p.m. So that's why setting aside the biology in real world, what time you end your dinner will indirectly influence what type of food you are more likely to eat. So that's why we suggest that you try to finish that window relatively early so that one thing is you have less chance for consuming too much alcohol and unhealthy food, and second is your last meal is likely to happen at least two to three hours before your habitual bedtime so that you can have a better night's sleep.