The Connection Between Meal Timing and Weight Gain

With obesity rates on the rise, researchers continue to examine potential factors affecting body weight and BMI other than caloric intake and physical activity. Currently, there is a range of options for targeting obesity including surgery, medication, and even psychological interventions however, the majority are costly or invasive endeavors. The development and prevalence of wearable monitoring technologies has dramatically increased the data available to researchers and clinicians, providing an opportunity for improved personalized patient care, prevention strategies, and treatment methods dependent on individual lifestyle habits. Stemming from extensive personal monitoring, recent research implicates the power of small lifestyle changes such as sleeping habits and meal times and their effects on weight gain.

Previous research has identified a pattern between late caloric intake – after 8pm – and increased risk of obesity. A recent study evaluating the relationship between later circadian timing of food intake and increased body fat adds to the growing body of evidence against late meal times. Led by Dr. Adnin Zaman, a team of researchers from the University of Colorado in Denver examined the correlation between meal times and weight gain using in-depth personal monitoring.

Is Weight Gain Linked to Meal Timing? 

The results of Dr. Zaman’s study were presented at the ENDO 2019 conference, revealing a significant connection between food consumption during the circadian evening and high body fat levels independent of other more traditional risk factors. 31 overweight or obese adults were evaluated in the study; their sleep patterns, activity levels, and dietary choices were assessed to gain a comprehensive picture of potential risk factors. Each participant was monitored via an actiwatch that monitored their sleep cycle patterns, and an activPAL – an electronic device used to measure physical activity.  Participants input their daily nutritional intake via MealLogger, a smartphone application that collects photographs of each meal and meal times.  Dietary intake was then verified through the use of continuous glucose monitors.

Study Findings

This preliminary trial is meant to be part of an ongoing investigation into the interactions of meal times and weight levels, although the results uncover important information about the role of meal timing. An overall analysis of participant behavior revealed that most individuals consumed their food within an 11-hour window and got 7 hours of sleep each night. Participants who ate their meals later in the day had a higher BMI and greater levels of body fat than individuals who restricted their eating window to earlier hours.

Few studies have assessed the impact of meal timing on weight gain and sleep. Dr. Zaman’s team investigated whether individuals who ate later in the day lost sleep as a consequence, furthering the already known correlation between sleep loss and obesity. However, the study found that even the participants with later circadian timing reported an average of 7 hours of sleep, implying that sleep loss was not a driver affecting weight gain in late eaters.

As several studies have shown, restricting the eating window to earlier on in the day has the potential to lower obesity risks independent of other risk factors. Since restrictive calorie-controlled diets and rigorous exercise plans are challenging to maintain, small lifestyle changes such as altering meal times could prove to be more easily achievable.  However, due to the small-scale and short duration of Dr. Zaman’s study, a body of more extensive research is required before these findings can be implemented into practice. Additionally, Zaman and his team plan to replicate this experiment with participants who have a healthy BMI to determine whether the same correlation applies.