Over the last decade(s), there have been arguments both for and against the importance of meal & nutrient timing. You may have seen it argued that meal timing doesn’t matter at all, as long as you stick to your daily calorie intake, you’ll be ok. I’m sure you’ll also have seen recommendations that people should eat lots of little meals throughout the day, spaced 3 hours apart to maximise protein synthesis.
By going to either extreme, you could be missing out on ways to increase your clients' satiety through the day, improve their health, and accelerate them towards their goals, whilst building a routine that fits into their lifestyle. Remember, your client and making their nutrition work according to their lifestyle is the biggest priority.
With more recent research papers being published, it could be fair to say that the timing of meals is an important factor in your clients health and results. But some of the more recent research hasn’t purely focused on meal timing in itself, it’s looked into the timing of our meals in accordance to our daily biological body clocks (circadian rhythms).
Let me introduce to you this concept:
A relatively ‘new’ term in the field of nutritional science, first developed in 2005. In very general terms, chrononutrition is the area of nutrition that looks into our circadian rhythm and our day-to-day dietary routines.
Before we go further, a quick summary of circadian rhythms will prove useful for you as a trainer, so you can really see the effect nutrition can have on your clients body.
Circadian rhythms are “are physical, mental, and behavioral changes that follow a daily cycle.”
In our brain we have what’s seen as the “master clock” or central rhythm, a biological clock that cycles for about 24 hours (on average it’s 24 hours and 15 minutes). External stimuli can influence this with the main stimuli being light & dark, sleeping & waking and feeding & fasting.
You see, we don’t just have one body clock. In fact we have several that control an array of processes within the body, from hormone control to nutrient metabolism.
As individuals, if we chronically disrupt the alignment of these body clocks, the risk of suffering adverse health effects is increased.
For example misalignment has been shown to increase glucose levels, reduce sleep efficiency and reverse the daily cortisol rhythm.
Why does this matter for your client
Feeding is one of the stimuli that can affect some of the internal body clocks, and ultimately play a part in the regulation of these rhythms.
Circadian rhythms also impact how well nutrients are metabolised (broken down and used) once they have been consumed.
With the data we have available to use at the moment, this means that there could be “better” or “worse” times of the day to be consuming food.
Studies have shown a poorer metabolism of food when it is consumed at night time (important consideration if your client is a shift worker), poorer sleep quality and body composition.
The evidence points towards eating earlier in the day, but how early in the day is unclear. But within the first 2-4 hours of waking would be a good place to start for your client.
Should your client eat Breakfast
Naturally when talking about meal timing, the argument as to whether you should eat or skip breakfast is always going to come up. Clients will tell you that they’ve heard that eating breakfast kick-starts & boosts the metabolism (strictly speaking it doesn’t, much), others will tell you they’ve heard skipping breakfast increases fat burning (strictly speaking, you use fat as a fuel more, but it doesn’t lead to greater fat loss without a calorie deficit).
Advantages and potential benefits of consuming a meal earlier in the day include:
Should Your Clients stop or avoid eating at a certain time?
Now we’ve spoken about how clients may benefit from having meals, and potentially more of the daily food intake earlier in the day compared to night time, you may wonder whether clients should stop eating by a certain point of the day?
As previously mentioned, the thermic effect of food has been seen to be much less when consumed in the latter stages of the day compared to the morning. Consuming large meals in the evening has been linked to increased susceptibility of obesity and other cardiometabolic diseases.
This suggests that our clients, where possible, should avoid consuming larger meals in the evening as our bodies don’t metabolise them as well in comparison to when they are consumed in the morning.
More recent research is beginning to show that if night time feeding is to occur (again, thinking about our shift workers), it may be wise to choose low-calorie options (~<200kcal) as the negative effects reported with large intakes are not consistently reported with low-calorie intakes.
This being said, we know from fasting research that having a feeding window of 8-10 hours can provide many benefits from a health point of view for our clients.
(see here for our article on fasting/time-restricted feeding)
What Should Your Client Do?
Practically, using the information we have available to us so far (I anticipate a lot more to come in the coming years), it could be wise to try and match up your clients' feeding window to their other biological clocks (light-dark & sleep-wake).
Your client should understand that the time of day they choose to eat their meals can have health implications for them, with the potential for more positive ramifications with earlier ingestion of food in the day. If possible clients should try to avoid large night time meals where possible (the odd night time social here and there won’t be too detrimental).
If they are going to consume food into the night time, low calorie options (~ 200kcal or below) may be beneficial for avoiding negative health effects (we don’t have lots of data on this currently, but what we do have suggests this is a good idea).
Finally, if you clients can eat within a 8-10 hour window, this again, could be beneficial from a health and body composition point of view.
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