By Seema Gupta, MD, MSPH
Clinical Assistant Professor, Department of Family and Community Health, Joan C. Edwards School of Medicine, Marshall University, Huntington, WV
Summary Points
- Zhao et al conducted a multisite prospective cohort study of patients to evaluate the association between meal intervals and weight trajectory. A total of 547 adults (age 18 years and older) from three health systems in Maryland and Pennsylvania were enrolled in the study. Participants recorded at least one weight and height measurement in the two years before study enrollment (February 2019 to July 2019).
- The researchers developed the Daily24 smartphone application, which allowed participants to record their eating, waking, and sleeping patterns per 24-hour interval in real time. The eating habits evaluated in the study were meal time and the approximate size of a meal.
- The authors reported the mean period from the first to the final meal was 11.5 hours, waking up to the first meal was 1.6 hours, the last meal to sleep was four hours, and the sleep duration was 7.5 hours. Researchers found the time interval between the first and last meal, waking up and first meal, final meal and sleep, and total sleep duration were not linked with weight change across follow-up time at enrollment.
- The total daily number of large and medium meals was associated with gained weight during follow-up, while weight loss was observed for those with total number of small meals. Specifically, the average annual weight changes associated with a daily increase of a single, large, medium, or small meal were 0.69 kg (95% confidence interval [CI], 0.19-1.18), 0.97 kg (95% CI, 0.64-1.29), and -0.30 kg (95% CI, -0.53 to -0.07), respectively.
SYNOPSIS: Researchers found monitoring total caloric intake may be more effective for losing weight than intermittent fasting.
SOURCE: Zhao D, Guallar E, Woolf TB, et al. Association of eating and sleeping intervals with weight change over time: The Daily24 Cohort. J Am Heart Assoc 2023; Jan 18: e026484. doi: 10.1161/JAHA.122.026484. [Online ahead of print].
Many Americans struggle with their weight. Approximately 42% of U.S. adults are obese.1 Not only is obesity an expensive chronic disease, but it can lead to other maladies, such as type 2 diabetes, heart disease, osteoarthritis, asthma, obstructive sleep apnea, and some types of cancers. Achieving and maintaining a healthy weight includes a balance of nutritious eating, frequent physical activity, proper sleep, and stress control.
Managing obesity might require clinical interventions, including behavior-based tactics (to induce lifestyle change), pharmacotherapy, and surgery. There is interest in identifying alternative dietary weight loss techniques that involve either restricting energy intake to certain times of the day or extending the fasting interval between meals. These tactics can include intermittent fasting and time-restricted feeding (TRF), where food intake is restricted to four to 12 hours per day without a reduction in calorie intake.
Randomized trials have not demonstrated the benefit of TRF regimens compared with eating throughout the day but have shown favorable effects on several cardiometabolic risk factors, such as lipid profile, blood pressure, glucose regulation, and insulin resistance.2 However, these studies have been limited by small sample sizes and short durations.
Zhao et al conducted a multisite prospective cohort study of patients to evaluate the association between meal intervals and weight trajectory. A total of 547 adults (age 18 years and older) from three health systems in Maryland and Pennsylvania were enrolled in the study. Participants recorded at least one weight and height measurement in the two years before study enrollment (February 2019 to July 2019). The researchers developed the Daily24 smartphone application, which allowed participants to record their eating, waking, and sleeping patterns per 24-hour interval in real time. The eating habits evaluated in the study were meal time and the approximate size of a meal.
Approximately 80% of study participants were white, the mean age of the study cohort was 51 years, and 20% were men. Additionally, more than three-fourths of participants reported they had earned a college degree or beyond. The average body mass index was 30.8 kg/m2. The average follow-up time for weight recorded in the electronic health record was 6.3 years.
The authors reported the mean period from the first to the final meal was 11.5 hours, waking up to the first meal was 1.6 hours, the last meal to sleep was four hours, and the sleep duration was 7.5 hours. Researchers found the time interval between the first and last meal, waking up and first meal, final meal and sleep, and total sleep duration were not linked with weight change across follow-up time at enrollment.
The total daily number of large and medium meals was associated with gained weight during follow-up, while weight loss was observed for those with total number of small meals. Specifically, the average annual weight changes associated with a daily increase of a single, large, medium, or small meal were 0.69 kg (95% confidence interval [CI], 0.19-1.18), 0.97 kg (95% CI, 0.64-1.29), and -0.30 kg (95% CI, -0.53 to -0.07), respectively.
COMMENTARY
The results of this investigation do not seem to confirm previous studies that demonstrated intermittent fasting may improve the body’s rhythms and regulate metabolism. These findings by Zhao et al are interesting in that while the window of time between first meal to last meal was not associated with weight change, the average daily number of large and medium meals was associated with weight gain over time. This may suggest meal frequency and size, rather than the timing of meals, are stronger determinants of weight gain over time. The researchers found an association between eating large meals more frequently per day and weight gain, indicating more total caloric intake is the major driver of weight gain.
Furthermore, these findings also indicated participants with shorter time from wake up to first meal and with longer time from last meal to sleep appeared to gain less weight. However, the authors of previous studies have found similar results, but also have failed to find an association between eating frequency and weight changes, indicating issues with study design as well as lack of standardized approaches to measuring results.3,4
Zhao et al demonstrated that when we are facing weight changes over time, the frequency of meals, rather than the timing, might be a stronger determinant of weight change. Therefore, when counseling our patients about weight gain prevention, emphasizing limiting the frequency of large meals over restricting eating windows may be more beneficial.
REFERENCES
- Hales CM, Carroll MD, Fryar CD, Ogden CL. Prevalence of obesity and severe obesity among adults: United States, 2017-2018. National Center for Health Statistics. 2020. https://www.cdc.gov/nchs/data/databriefs/db360-h.pdf
- Trepanowski JF, Kroeger CM, Barnosky A, et al. Effect of alternate-day fasting on weight loss, weight maintenance, and cardioprotection among metabolically healthy obese adults: A randomized clinical trial. JAMA Intern Med 2017;177:930-938.
- Kahleova H, Lloren JI, Mashchak A, et al. Meal frequency and timing are associated with changes in body mass index in Adventist Health Study 2. J Nutr 2017;147:1722-1728.
- Kant AK, Schatzkin A, Graubard BI, Ballard-Barbash R. Frequency of eating occasions and weight change in the NHANES I Epidemiologic Follow-Up Study. Int J Obes Relat Metab Disord 1995;19:468-474.
Researchers found monitoring total caloric intake may be more effective for losing weight than intermittent fasting.
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