Lecturer School of Psychology University of Sussex
Many of us are embarking on new goals this month. January is the time for letting go of old habits and establishing new and healthier ones. One of the most popular goals people set is to lose weight. Usually, the goal focuses on the amount of food that we eat and then we brace ourselves for the difficult days ahead. Well, there may be an easier way to reach our goal, with perhaps less unpleasantness and a great deal of benefits. Just pay attention to the time that you eat.
The most popular approach to weight loss revolves around calorie deficit. Calorie deficit refers to the number of calories one consumes each day and the number of calories that one burns or uses up through physical activity and basic bodily functions. Each type of physical activity like standing, walking, cooking, etc ‘burns’ or uses up energy from the food that we eat. Basic bodily functions are a less obvious way that we use up energy from food, such as maintaining our bodies at the optimal temperature (~36.8C), digesting our food and processing information. If we eat more calories than we use each day, that extra energy we get from food will be stored in our bodies for future use as fat. If this surplus of energy continues, we will gain weight over time. So, it makes sense to pay attention to our food consumption and our physical activity. If there is a balance between ‘calories-in’ and ‘calories-out’, we will most likely maintain our body weight. If we consume more than we spend, we will most likely gain weight because of the excess consumption of calories.
If the goal is to lose weight then the obvious thing to do would be to cut down on the calories-in, so that we can create a caloric deficit, meaning that the body does not have enough energy at hand, from the food consumed on a given day, so it has to start using the stored energy from our fat cells and over time, this will most likely result in loss of body weight.
One strategy that can help us get the true picture of what our feeding behaviour is like, is to keep a log of what we consume each day. Anything besides water counts as food so writing things down in a notebook or a digital form will be an objective way for us to get a sense of what and how much we consume in a day, a week or even a fortnight. Perhaps this exercise alone will be enlightening for many people, as we tend to underestimate what we eat. A tea or coffee with milk or a glass of wine is often mistakenly not considered food. But how about when we eat?
A study was conducted in 2015 that asked participants to report everything they ate using an app on their phone. Through this study, it became apparent that in contrast to the general belief that we eat three meals per day, breakfast, lunch and dinner, people were consuming meals and snacks quite randomly and ate for a long time during the 24-hour period. Then, researchers restricted the time that participants could consume their meals and snacks, to a 10-12h window. They didn’t tell them what to eat or how much to eat, they just asked them not to eat past a given time in the evening. What they found was astonishing, in that these participants lost weight, and had more energy and better sleep. Animals that were genetically identical, took part in a similar experiment where they were given a high-fat diet to eat, but for half of the animals this food was available throughout the 24-hour period whereas for the other half, food was available for consumption only during their active phase. It turns out that the animals that had their food only during their active phase, had a healthy profile, whereas their counterparts were suffering from many health conditions.
The time that we eat may be more important for our body weight regulation and health than the amount and type of food. Of course, we should care about what we consume because we need the nutrients to satisfy our body’s needs but the circadian timing of food consumption is fundamental and often disregarded. As I wrote on several occasions, we are all intimately connected to the 24-hour rotation of the earth on its axis, and our bodies, every cell of what makes us, has a time mechanism that dictates to that cell, that organ, and our whole body that it is time to conduct certain functions and to inhibit others. Given that we are creatures of the day, and we are ‘programmed’ to be active during the day and sedentary during the night. Our eating and digestion are also tied to this cycle.
Being obese and overweight is very much a phenomenon of modern society with many negative consequences for our health and well-being. It is true that the availability of calorie-dense foods, has contributed to the prevalence of obesity but food availability increased so did our access to a light switch and the ability to extend daytime and our ability to snack and have beverages beyond daytime. In reflecting on our eating patterns, it is important to consider our alignment with our circadian clock, and whether our eating falls within the 10-12h period of our active phase or whether it extends well into the night, which may go hand in hand with delayed sleep.
Becoming aware of the circadian rhythm and adjusting our activity, sleep and eating patterns to be in sync with the circadian rhythm dictated by our biology will help to keep our body weight in check and prevent other body weight-related conditions such as diabetes and metabolic disease. It may take time to adjust to a new eating pattern but you can start gradually to refrain from eating past a certain time in the evening.
You can try this new pattern of mindful eating for a couple of months. By then, you may be able to notice positive changes in your level of hunger, the quality of your sleep, and your level of alertness and energy during the day.
Happy New Year!
Posted in sleep on Jan 01, 2024