While at the end of the day what we eat is at the root of our response to food, the “when” we eat also plays a significant role. Understanding this role can give you even more tools to use to optimize your blood sugars.
Circadian Rhythm and Meal Timing
The human body is designed to work on a circadian rhythm or daily cycle based on the body’s internal clock. These cycles are directly regulated by environmental cues, such as light, and are important factors in everything from sleep schedules to body temperature regulation to hormone levels.
These daily cycles also include factors related to metabolism, and this intersection between circadian rhythms and nutrition is known as chrononutrition. Hormones like cortisol, insulin, and leptin are all based on that daily circadian rhythm, so when there’s a misalignment of food intake with this daily cycle (such as eating late in the evenings or overnight), this can lead to several health problems, including insulin resistance.
Allowing some time for fasting each day also allows your body’s eating hormones to reset. Being constantly in the fed state without any periodic overnight fasting can activate anabolic processes, including lipogenesis (fat-storing). On the other hand, allowing some overnight fasting can activate catabolic pathways that allow for important recovery and repair to take place.
In a practical sense, this means that you likely won’t tolerate food as well later in the evenings or overnight since insulin sensitivity significantly decreases as the day goes on. You may see this in your CGM data if you have a higher response to a meal for dinner versus if you have that same meal for lunch.
Another way that you’ll see this in your glucose values is in higher overnight values and even higher fasting glucose values the next morning. So if you’re struggling to get your fasting glucose down, it may be worthwhile to take a closer look at when you’re consuming your last meal, snack, or beverage of the day.
Some general guidelines to use this information to your advantage include:
Aim for at least 12-14 hours of fasting each night (unless advised otherwise by your diabetes management team)
Shift your eating window earlier rather than later in the day. For example, if you’re eating from noon to 8 pm, consider slowly shifting this forward to 8 am to 4 pm
Try to consume most of your food during daylight hours
Aim to have your last bite of food at least 3 hours before bedtime
Eating Around Exercise
Chapter 4 will discuss the relationship between physical activity and glucose values in more detail, but exercise can help optimize our blood sugars in a variety of different ways, primarily by enhancing insulin sensitivity and helping to “use up” some of the extra glucose from our meal to fuel our activity.
This information can be used to your advantage to optimize your body’s response to carbohydrates, helping you to be able to still enjoy foods that you love while maintaining more stable glucose values. Here are some strategies that may work for you:
Add in a brisk walk after a meal to help burn through some of that extra glucose
Save higher-carb food items for after a workout when you are experiencing the benefits of enhanced insulin sensitivity