The University of Alabama is conducting research on the effects of early time-restricted feeding for weight loss.
Time Restricted Feeding
First, let me admit that I detest writing about the timing of nutrition. When it comes to nutrition, I think there are few subjects where opinions differ more and studies contradict each other more. When I write about research like that from the University of Alabama, I see it merely as one of the voices in a cacophony of disagreement. The last thing I would want is for you to remember a single catchphrase from this article and then spread it as the sole truth.
Researchers from Alabama conducted a study on the effects of early time-restricted feeding, or eTRF. In eTRF, food is only consumed in the morning and early afternoon. Their findings suggest this limits fluctuations in hunger and causes a change in fat and carbohydrate metabolism. These findings were announced in a presentation at the Obesity Society Annual Meeting in New Orleans, Louisiana [1].
Eating only during a much smaller window of time than people are typically used to may help with weight loss. We found that eating between 8 a.m. and 2 p.m. followed by an 18-hour daily fast kept appetite levels more even throughout the day, in comparison to eating between 8 a.m. and 8 p.m., which is what the average American does.
-Courtney Peterson, University of Alabama
The study indicates that eating an early dinner, or skipping dinner, helps with weight loss. However, the researchers also acknowledge that further research is needed to confirm this. Previous studies on rodents came to the same conclusion according to the researchers. In those studies, eTRF led to less body fat and a reduced risk of developing chronic diseases. I assume they are referring to research conducted on mice in 2012 [2].
In that study, mice were fed a high-fat diet that led to obesity when eaten normally throughout the day. However, when TRF was applied, overweight could be prevented with the same diet. When eating for 8, 9, or 12 hours, the mice did not gain weight. Only when eating over 15 hours a day did the mice become obese. Less than 12 hours of fasting per day in that study was not enough to protect against the effects of the high-fat diet. The effect of fasting was mainly achieved through the (inhibitory) effect on the anabolic hormone insulin, which can promote fat storage.
In a study on mice, the University of California in 2014 looked at the effect on different diets (e.g., high in fats, sucrose, or fructose) [3]. Even under these different conditions, TRF proved to protect against obesity.
‘Internal Clock’
The Alabama researchers point to the existence of an internal clock and that many parts of metabolism work optimally in the morning. Therefore, eating in accordance with this clock, by eating early, could lead to many positive health effects.
For the study, Peterson and colleagues followed 11 overweight men and women for four days during which they ate between 08:00 and 12:00. On four other days, they ate between 08:00 and 20:00. The effect on metabolism and hunger was then measured. In both cases, the same number of calories were consumed and each test was conducted under supervision.
eTRF did not lead to more calories being burned. However, it did result in less fluctuation in hunger and increased fat burning during nighttime hours. It also appeared that the body was more easily able to switch from burning carbohydrates to burning fats.
The researchers themselves understand that this was only a small-scale study and of short duration. So it’s questionable how much this would translate to long-term effects.
References
- uab.edu/news/health/item/7869-time-restricted-feeding-study-shows-promise-in-helping-people-shed-body-fat
- Time-restricted feeding without reducing caloric intake prevents metabolic diseases in mice fed a high-fat diet. Hatori M, Vollmers C, Zarrinpar A, DiTacchio L, Bushong EA, Gill S, Leblanc M, Chaix A, Joens M, Fitzpatrick JA, Ellisman MH, Panda S Cell Metab. 2012 Jun 6; 15(6):848-60.
- Chaix A, Zarrinpar A, Miu P, Panda S. Time-restricted feeding is a preventative and therapeutic intervention against diverse nutritional challenges. Cell metabolism. 2014;20(6):991-1005. doi:10.1016/j.cmet.2014.11.001.
