Could changing your client’s meal time be the magic bullet that tips the scales? Is the advice to not skip breakfast obsolete? Perhaps.
Scientists recently published a study in the journal Obesity indicating that incorporating strategies such as eating earlier in the day or intermittent fasting facilitates weight loss by reducing appetite instead of burning more calories. The research initially shows how the timing of meals impacts 24-hour energy metabolism when food consumption and frequency of meals are matched.
According to Eric Ravussin, PhD, an author on the study and associate executive director for clinical science at Louisiana State University’s Pennington Biomedical Research Center in Baton Rouge, "Coordinating meals with circadian rhythms, or your body's internal clock, may be a powerful strategy for reducing appetite and improving metabolic health,".
Courtney Peterson, PhD, lead author of the study and an assistant professor in the Dept. of Nutrition Sciences at the University of Alabama at Birmingham believes that most people find meal timing strategies helpful for dropping pounds or maintaining weight loss as these methods naturally reduce appetite, which could help people eat less.
According to Peterson and her team, modifying meal time may help people burn more fat during a 24-hour period. A form of daily intermittent fasting known as early Time-Restricted Feeding (eTRF), where dinner is consumed early in the afternoon, helped to improve subject’s ability to burn fat instead of carbohydrate for energy. This is an aspect of metabolism called metabolic flexibility. The study’s authors caution that the results on fat-burning are preliminary and more research is indicated to see if these methods are beneficial in longer term studies.
The small study included 11 overweight men and women. Subjects aged 20-45 years old were in overall good health with a BMI between 25-35, body weight between 68 and 100 kg, a normal bedtime hour between 9:30-12:00 AM and, for women, normal menstrual cycles.
Two different meal timing strategies were trialed in random order: the control schedule had subjects eating 3 meals over a 12-hour period with breakfast at 8:00 AM and dinner at 8:00 PM and a eTRF plan where subjects consumed three meals over a 6-hour period with breakfast at 8:00 and dinner at 2:00 PM. Similar amounts and types of foods were eaten on both schedules. The control schedule had a fasting period of 12 hours daily and the eTRF schedule had participants fating for 18 hours daily.
Subjects adhered to the different schedules for four days in a row. On the last day, scientists measured the metabolism of subjects using a respiratory chamber -- a room-like device -- where researchers calculated number of calories, carbohydrates, fat, and protein burned. Appetite levels of participants were also measured every three hours during their waking hours as well as hunger hormones in the morning and evening hours.
Despite eTRF not significantly affecting the number of calories burned by participants, the researchers noted that eTRF did reduce grehlin levels, the hunger hormone, as well as some aspects of appetite. Fat-burning was also higher over the 24-hour period.
The researchers were able to explore time restricted-feeding (daily intermittent fasting) in addition to meal timing strategies that included having meals earlier in the day in sync with circadian rhythms. The scientists note that these eating strategies likely have common benefits to eTRF.
Dietitian Holie Raynor, who was not affiliated with the research states, "this study helps provide more information about how patterns of eating, and not just what you eat, may be important for achieving a healthy weight." Raynor is a professor and interim dean of research in the Department of Nutrition, College of Education, Health, and Human Sciences at The University of Tennessee, Knoxville.
According to Peterson and colleagues, earlier research conflicted on whether alterations in meal timing facilitated weight loss by helping people burn extra calories or reduce appetite. Rodent studies suggest these changes induce more calorie burning, but other studies indicate no difference. The authors note that earlier studies did not directly calculate number of calories burned or may have had other design flaws.
Here are a few tips for dietitians’ clients that want to triy intermittent fasting:
- Intermittent fasting is not safe for those who are pregnant, nursing, or have diabetes
- Intermittent fasting is not advised for those with eating disorders or at high risk of eating disorders
- Morning coffee is fine, but it must be black (no cream or sugar)
- Drink adequate water during periods of fasting to prevent dehydration
- Brush and floss your teeth after your last meal to reduce desire to eat. This signals your body, “the kitchen is closed”.
- Limit snacking between meals to allow the body’s insulin levels to decline.
- If trying intermittent fasting, ideally aim for 14-16 hours in a fasting state. This means breakfast at 10 or 11 AM, lunch at 2:00 or 3:00 PM and dinner finished by 7 PM. In addition, aim for a smaller, earlier dinner and not snack after 7 PM. Other studies have shown that “time restricted feeding” has resulted in weight loss, even without calorie restriction.
By Lisa Andrews, MED, RD, LD
- Eric Ravussin, Robbie A. Beyl, Eleonora Poggiogalle, Daniel S. Hsia, Courtney M. Peterson. Early Time?Restricted Feeding Reduces Appetite and Increases Fat Oxidation But Does Not Affect Energy Expenditure in Humans. Obesity, 2019; 27 (8): 1244 DOI: 10.1002/oby.22518
- Rona Antoni, Tracey M. Robertson, M. Denise Robertson, Jonathan D. Johnston. A pilot feasibility study exploring the effects of a moderate time-restricted feeding intervention on energy intake, adiposity and metabolic physiology in free-living human subjects. Journal of Nutritional Science, 2018; 7 DOI: 10.1017/jns.2018.13
Printable Infographic: Intermittent Fasting Tips
Stephanie Ronco has been editing for Food and Health Communications since 2011. She graduated from Colorado College magna cum laude with distinction in Comparative Literature. She was elected a member of Phi Beta Kappa in 2008.