Front-loading calories early in the day reduces hunger but does not affect weight loss

There’s the old saying about diets that one should “eat breakfast like a king, lunch like a prince, and dinner like a pauper,” based on the belief that consuming most of your daily calories in the morning optimizes fat loss. weight by burning calories more efficiently and quickly. But according to a new study published Sept. 9 in Cellular metabolismSo, whether a person eats their largest meal early or late in the day doesn’t affect how their body metabolizes calories. However, people who ate their largest meal in the morning reported feeling less hungry later in the day, which could encourage easier real-world weight loss.

“There are many myths around when to eat and how it could influence body weight or health,” says lead author Professor Alexandra Johnstone, a researcher in the field of appetite control at the Rowett Institute, University of Aberdeen, Scotland. “This has been largely driven by the field of circadian rhythm. But we in the field of nutrition have wondered how this could be possible. Where would the energy go? We decided to take a closer look at how time of the day interacts with metabolism.

In this study, researchers recruited healthy subjects who were overweight or obese to monitor their diets and measure their metabolism over a period of time; 16 men and 14 women completed the study. Each participant was randomly assigned to eat either a loaded breakfast in the morning or a loaded breakfast in the evening. diet for four weeks. The diets were isocaloric, with a balance of 30% protein, 35% carbohydrate, and 35% fat. After a one-week washout period in which calories evened out throughout the day, each participant switched to the opposite diet for four weeks. In this way, each participant acted as their own study control.

Throughout the study, subjects’ total daily energy expenditures were measured using the doubly labeled water method, an isotope-based technique that analyzes the difference between the turnover rates of hydrogen and oxygen in body water as a function of the carbon dioxide production. The primary endpoint of the study was energy balance measured by body weight. Overall, the researchers found that energy expenditures and total weightloss they were the same for the morning-loaded and evening-loaded diets. The subjects lost an average of just over 3 kg (about 7 pounds) during each of the four-week periods.

Secondary endpoints were subjective appetite control, glycemic control, and body composition. “Participants reported that their appetites were better controlled on days when they ate a larger breakfast and that they felt satiated throughout the rest of the day,” says Johnstone. “This could be very useful in the real world environment, versus the research environment in which we were working.

A limitation of the study is that it was conducted under free-living conditions rather than in the laboratory. Also, certain metabolic measurements were only available after breakfast and not after dinner.

Johnstone notes that this type of experiment could be applied to the study of intermittent fasting (also called time-restricted eating), to help determine the best time of day for people on this type of diet to consume their calories.

The group plans to expand their research on how time of day affects metabolism by conducting studies similar to the one described here in subjects who work shifts. It is possible that these people may have different metabolic responses due to the disruption of their circadian rhythms. “One thing that’s important to keep in mind is that when it comes to timing and diet, there may not be one diet that fits everyone,” Johnstone concludes. “Solving this will be the future of diet studies, but it’s very hard to measure.”