Does Mealtime Matter for Weight Loss or Blood Glucose?
By now, most of us have heard of or even tried the eating protocol called Intermittent Fasting. This dietary regimen focuses on the timing of meals, where portions of time are allocated to fasting and designated times are scheduled for eating. Intermittent Fasting (IF) has become one of the most popular health and fitness trends due to its ability to promote weight loss, improve health and its ease of use. Today we’re going to take a closer look at what the science is saying about the IF protocol and its effect on weight loss, blood glucose and Type 2 Diabetes.
Part 1 - Time-Restricted Eating and Weight Loss
What is Time Restricted Eating?
As the name suggests, Time-Restricted Eating directly focuses on when you eat, not what you eat.
While the term encompasses a wide variety of eating styles, patterns and goals, TRE generally refers to a diet plan in which meals are eaten during a specific range of hours per day.
For example, some adopters of Time-Restricted Eating might choose to consume food only between the hours of 8 AM and 6 PM, with a subsequent period of fasting from 6 PM through 8 AM the next morning.
Typically, early TRE focuses on eating food during solely daytime hours. Studies show there to be a correlation between this strategy and weight loss, but in different ways than you might think:
The primary way that early TRE contributes to weight loss, according to studies, is by lowering the production of ghrelin, the hormone our body uses to stimulate our appetite.
By basing our meals around our circadian rhythms, particularly during daylight hours, we may decrease feelings of hunger that can lead to excess calorie consumption. Over time, this can contribute to a caloric deficit that is a crucial step on the path to weight loss.
Preliminary research also suggests that early TRE can help the body change the way it produces energy.
Typically, the body relies on burning carbohydrates (our primary energy source) to give us fuel throughout the day. However, participants in an early-restricted feeding cycle study had an improved ability to burn fat for energy rather than carbohydrates, leading to a metabolic change that can contribute to weight loss.
While less widespread, later TRE has been the subject of numerous studies on the correlation between meal timing and weight loss.
Typically referring to a diet plan in which food is consumed later in the day (think lunch and dinner hours), later TRE has been demonstrated to have potentially adverse effects on weight loss.
Often adopted by those who view the afternoon and evening as their “primary” hours (i.e., people who prefer to sleep in and stay up late), this eating style sometimes consists of two meals, one in the afternoon and one in the evening.
According to a wide-ranging study of obese subjects by the National Center for Biotechnology Information, those who adopted late lunches (after 3 PM) as part of their TRE lost less weight than those who ate earlier lunches, regardless of several factors such as age, gender, hormones, physical activity etc.
Within the same research group, another study measured the effects of afternoon meal-timing on weight loss in women divided among two groups: those who had early lunches (before 1 PM) and those who had late lunches (after 4:30 PM). While further research is necessary, this localized study revealed that eating larger meals later in the day can interrupt the rhythm of our microbiome, which can negatively affect our metabolism.
Similarly, other scientific resources claim that late dinners (often labeled as 7 PM for those with early-melatonin onset and as late as 1 AM for those with late-melatonin onset) can also adversely affect weight loss.
By intentionally disrupting our natural circadian rhythms, late dinners can alter hormone production that controls appetite and energy use, which can make weight loss more challenging.
TRE Impact on Hormones
As we mentioned before, TRE can have a prominent effect on your hormone production, especially when it comes to ghrelin.
Depending on the model of TRE you employ, ghrelin production can be curbed or increased throughout the day. In general (while there is a broad range of both research and opinions), many studies have shown that early TRE can help limit ghrelin production while later TRE can affect it adversely.
Similarly, TRE can affect the production of leptin (the hormone responsible for curbing hunger). Specifically, later TRE can diminish leptin production, meaning that this style of food consumption can sometimes leave you feeling hungrier over more extended periods of time.
Two other hormones often mentioned in TRE research are insulin and HGH.
Some studies show that early TRE can be a good way to decrease insulin levels, which is excellent for controlling blood sugar (as we will discuss in detail below). This reduction works hand in hand with other potential benefits of early TRE, such as curbed appetite and better blood pressure levels.
The relationship between healthy TRE and HGH is also fascinating. Some studies have shown that TRE can lead to as high as a 300% increase in HGH over a three day period, which is remarkable.
Considering the role HGH can play in protecting tissue throughout our brain and body, these findings suggest that Intermittent Fasting techniques can have a far wider impact on our bodies than some might imagine.
Part 2 - Intermittent Fasting and Blood Glucose Control
Impact of TRE on Blood Sugar and Diabetes
As we discussed earlier, healthy TRE can play a positive role in the regulation of blood glucose (blood sugar) levels. Backed by focused research and studies, this information is particularly important for people who are at a higher risk of diabetes.
In fact, a well-referenced study from the University of Adelaide uses glucose monitoring to show that TRE can significantly improve the body’s ability to control glucose, a fantastic finding for those on the precipice of a Type 2 Diabetes diagnosis.
This study’s revelation on the effect of TRE on blood glucose control is also unique because it suggests that the subjects experienced glucose regulation benefits regardless of whether they practiced early or later TRE, meaning that TRE can be easier to adapt for people of different circadian rhythms.
While these results are preliminary and need further verification and experimentation, hard data and testimonials from subjects reveal that TRE can lead to a boost in glucose regulation that can minimize the risk of developing Type 2 Diabetes, a disease that affects over 20 million Americans.
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