Timing Counts for More than Calories in Weight Loss

In a recent study from the University of Texas Southwestern Medical Center in Dallas, researchers have found evidence that connects meal times with the ability to lose weight. Findings also support the idea that the body’s natural sleep cycles are disrupted when food is consumed at irregular times. The study was published by Cell Press journal in July 2017. The Howard Hughes Medical Institute and the National Institute on Aging sponsored the research.

Exploring Weight Loss Variables

Previous research has confirmed that eating a calorie-restricted diet increases longevity. The team from the UT Southwestern Medical Center wanted to further explore the relationship between body rhythms, like the circadian cycle, and the time of day calories are consumed.

These types of studies can be difficult to structure. To get the most accurate results from a feeding study, the animal subject would have to be hand-fed and observed constantly. Researchers from the current study sought to simulate long-term results in a way that could be measured during normal working hours. An automated feeding system was developed that allowed researchers to control the food intake of different test groups. Sensors helped track the movements and reactions of lab animals. Researchers were able to note information, like consumption time, that can significantly affect the outcome of data analysis.

Animal Observation Study

Five groups of lab animals were used for the study. Each group was assigned a unique eating regime that varied by calorie content and feeding time. Data analysis showed the group of mice that received reduced-calorie night time feedings was the only group to display weight loss.

Two other groups of animals received feedings during daylight hours. Rats are nocturnal, therefore eating during the day is a disruption of their natural cycle. These groups were observed to remain as active at night as they were during the day, which may indicate chronic sleep deprivation. Researchers believe the lack of sleep is a symptom of disrupted circadian rhythms.  

Circadian rhythms, otherwise known as the “internal clock”, is a set of biological activities that regulate cycles of sleep and waking. Previous studies have suggested that this internal sense of time also influences other body processes, like digestion and metabolism. The current study adds weight to those theories.

“Translated into human behavior, these studies suggest that dieting will only be effective if calories are consumed during the daytime when we are awake and active. They further suggest that eating at the wrong time at night will not lead to weight loss even when dieting,” said Dr. Joseph S. Takahashi, Chairman of Neuroscience at UT Southwestern.

Implications for Further Research

While the study proves a link between weight loss and consumption timing, researchers believe the study’s greatest contribution may be the automated feeding system. Existing studies that explore calorie-reduced diets use daytime feeding schedules. The results of the current study show that this method may be skewing results and leading to false conclusions. The automated feeding system will allow future researchers to conduct longer and more biologically accurate experiments.

“Despite the importance of these factors, manipulating when and how much food is available for extended periods has been difficult in past research. This automated system, which can be scaled up for large and very long longevity studies, provides the means to address open questions about what mechanisms extend lifespan in mammals, and whether it is actually the calorie reduction or the time at which food is consumed that extends lifespan,” Dr. Takahashi said.