The best time of day to eat for maximizing performance & fat loss
Click-bait title, I know. But hey, it got you here didn’t it? Spoiler alert: There is no “right” way. As with anything involving nutrition or fitness, what is best for the individual will vary based on the goals they are trying to achieve combined with countless individual factors (schedule constraints, personal preference, etc.).
If you are more scientifically inclined, I urge you to watch this lecture by Danny Lennon, for a very thorough discussion on this topic. I will be attempting to approach the topic in a way that is slightly easier to understand to those of us who do not hold advanced degrees in nutrition or biological sciences, but if you do fall under that category or are just a super-nerd (like me), I highly recommend the lecture above. Now, let’s get into the nuance!
There are currently two camps of people out there in the fitness industry:
Camp A: Hey BROTHER all ya gotta do is only eat between the hours of 12 PM-1 PM, it doesn’t matter what or how much you eat, you’re going to get shredded and the fat will just melt right off! Whatever you do, do NOT eat past 5 PM it will go straight to your gut fat!
Camp B: Yooooo dude don’t listen to all that mumbo jumbo, just get your calories and macros straight and you can eat at midnight if you want! That meal timing stuff is just overcomplicating things unnecessarily.
As I am sure you have guessed by now, both of these camps are misguided and inaccurate in some sense. As a general rule of thumb, whenever you see two very extreme and opposing viewpoints in nutrition and fitness topics, the truth can probably be found somewhere in the middle. To give a better idea of where the above campers went wrong, let’s remind ourselves of the nutritional priorities, and where nutrient timing falls on that list.
As you can see, energy balance, macronutrient distribution, and micronutrients all play a more important role than anything we will talk about in this article. So, if you’re concerned with whether or not you should have that bowl of rice at 6PM after a tough workout, even though your favorite IG influencer told you it will literally kill you, but you haven’t mastered the first three priorities, I would advise you to refocus your efforts. In general, the more advanced your goals are, the more justifiable it is to spend time and effort worrying about the things closer to the top of the pyramid. For example, if your goals are to just be generally healthy and have a balanced lifestyle, you can probably get away with never thinking about nutrient timing or supplements. However, if you’re a dedicated athlete trying to squeeze every bit of performance out of your body as possible, it may be worth delving into the minutiae that lives at the top of the pyramid. Neither of these goals is inherently better or more valuable than the other, but every nutritional intervention must be looked at with that cost-benefit analysis in mind. In other words, where are your limited sources of time, effort, and money going to be best spent?
With all that context out of the way, let’s get to the meat and potatoes. Nutrient timing is generally discussed in relation to two things: the circadian rhythm, which are your natural internal processes that ebb and flow, and repeat every 24 hours or so; and timing around training sessions. In this article, I will discuss how each of those can affect weight/fat loss, and then separately discuss performance implications.
Nutrient Timing and the Circadian Rhythm
There are countless biological processes that abide by the circadian rhythm (they change based on the time of day). Among those are some related to metabolism such as the rate of gastric emptying (how quickly food clears the stomach and enters the intestines), beta-cell function (responsible for producing and releasing insulin), and diet-induced thermogenesis (the increase in caloric expenditure you see after eating a meal). In all of these markers, it appears that biasing your caloric intake to more calories earlier in the day gives a slight advantage (1) (2) (3). A recent study from 2020 showed that diet-induced thermogenesis (DIT) was 2.5 times higher in the group consuming a high calorie meal in the morning compared to the same amount of calories in the evening (4). It is worth remembering that DIT is a small slice of the energy expenditure pie, contributing to about 5-15% (5) of your daily energy expenditure, so the difference in daily caloric balance (expenditure vs. intake) between the two groups is relatively small, but over time could prove to be significant. Regardless, when it comes to body composition and overall health markers, there seems to be a slight advantage to biasing a bigger proportion of your calories to the earlier parts of the day.
Then we have time-restricted feeding (TRF), which includes the very popular intermittent fasting approach. In this strategy, the idea is to restrict the number of hours you are actively eating. This can be 12, 8, 6, or even 4-hour windows, outside of which you refrain from eating. Critics of TRF will often say that this is simply a way to achieve a caloric deficit, since you can only eat so much in a smaller feeding window, and there is nothing magical about TRF. While there is some merit to that argument, even if TRF was simply creating a caloric deficit with no other benefits, that would still be a huge win because it offers people struggling with weight-loss ONE easy modification to make to their diet that could potentially help them achieve that deficit. One study that demonstrates this is from the University of Surrey in the UK, where subjects were told to move their normal breakfast time forward by 1.5 hours, and their dinner time back by 1.5 hours, effectively creating a time-restricted feeding scenario. This was the only instruction given to participants, and it resulted in a significant decrease in body fat over the course of 10 weeks (6). TRF remains a useful strategy for weight/fat loss goals, and combined with the information from the previous section, it is probably advisable to keep those windows to the earlier parts of the day (7 am-3 pm vs. 1 pm-9 pm).
Nutrient Timing for Performance
Like with most things nutrition and fitness-related, the conversation changes and more nuances emerge when the goal becomes performance optimization. There are several situations where the above recommendations would do more harm then good. For example, if an athlete likes to train in the evening, we would in almost no circumstance recommend that they refrain from eating anything until the following morning (the one exception I can think of is endurance athletes who do this to intentionally deplete glycogen stores for their workout the next morning in order to enhance fat oxidation capacity). In most situations, the benefits from getting in some protein and carbohydrates soon after a workout, regardless of the time of day, will vastly outweigh any of the negative outcomes that can potentially come from eating late in the evening. Another example would be an athlete who is struggling to get enough calories in throughout the day to achieve their goals. In this instance, TRF would interfere with the ability to adhere to the more important calorie balance principal that lays the foundation of our nutritional priorities pyramid. In general, if you need to break certain “rules” pertaining to things further up the pyramid in order to adhere to things further down the pyramid, you should do so. Every sporting scenario has distinct nutrient timing strategies, far too many to cover in this article. If you’re looking for guidance on specific nutritional strategies for certain sporting contexts, check out our Performance Nutrition program.
Practical Takeaways
Time-Restricted Feeding (TRF) can be an effective standalone diet modification to achieve weight/fat loss goals.
Evidence suggests it is generally preferable to bias the majority of daily caloric intake towards the beginning of the day vs. closer to biological night (a feeding window of 7 am-3 pm is likely better than a window from 1 pm-9 pm).
If an athlete is going to implement TRF strategies, their workout should be done sometime inside the feeding window to ensure proper nutrient intake before/after training.
Do not let nutrient timing considerations outweigh those of energy balance, macronutrient breakdown, and micronutrient intake.
In conclusion, nutrient timing can be an effective tool for weight/fat loss or performance enhancement if manipulated correctly and specifically for those goals. However, if implementing certain nutrient timing strategies compromises your ability to adhere to the more important nutritional priorities (energy balance, macronutrients, micronutrients), or do not fit certain aspects of your desired lifestyle (social life, evening training sessions) then do not force yourself to fit into any sort of rigid guidelines. Evaluate the information, and make independent decisions based on your goals, or those of your clients.
Written by: Chris Bonilla, Black Iron Nutrition Performance Coach
References
Goo RH, Moore JG, Greenberg E, Alazraki NP. Circadian variation in gastric emptying of meals in humans. Gastroenterology. 1987 Sep;93(3):515-8. doi: 10.1016/0016-5085(87)90913-9. PMID: 3609660.
Morris, C. J., Garcia, J. I., Myers, S., Yang, J. N., Trienekens, N., & Scheer, F. A. (2015). The Human Circadian System Has a Dominating Role in Causing the Morning/Evening Difference in Diet-Induced Thermogenesis. Obesity (Silver Spring, Md.), 23(10), 2053–2058. https://doi.org/10.1002/oby.21189
Qian, J., Man, C. D., Morris, C. J., Cobelli, C., & Scheer, F. A. (2018). Differential effects of the circadian system and circadian misalignment on insulin sensitivity and insulin secretion in humans. Diabetes, Obesity and Metabolism, 20(10), 2481-2485. doi:10.1111/dom.1339
Richter J, Herzog N, Janka S, Baumann T, Kistenmacher A, Oltmanns KM. Twice as High Diet-Induced Thermogenesis After Breakfast vs Dinner On High-Calorie as Well as Low-Calorie Meals. J Clin Endocrinol Metab. 2020 Mar 1;105(3):dgz311. doi: 10.1210/clinem/dgz311. PMID: 32073608.
Ho, K. (2018). Diet-induced thermogenesis: fake friend or foe?, Journal of Endocrinology, 238(3), R185-R191. Retrieved Jan 26, 2021, from https://joe.bioscientifica.com/view/journals/joe/238/3/JOE-18-0240.xml
Antoni, R., Robertson, T. M., Robertson, M. D., & Johnston, J. D. (2018). 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, 7. doi:10.1017/jns.2018.13