For this edition we have Harry Smith, from the Centre for Nutrition, Exercise and Metabolism at the University of Bath. Harry is studying the importance of meal timing for aspects of our health. So as time is ticking (and I am getting hungry)… let’s tuck in.
Key question: Does the timing of my meals matter for my health?
What is the body-clock?
Humans operate on a 24-hour day, and have developed a body clock which reflects this (the fancy science name is our circadian rhythms). The body clock is controlled by a small portion of the brain known as the suprachiasmatic nucleus. This part of our brain (don’t worry about the long name) helps to regulate our physiology based on changes in our environment, such as light exposure in the morning. This helps our bodies anticipate changes in our behaviour, such as when we are about to eat, which can help to prepare our tissues for the changes that then happen. Yes… the human body is pretty awesome...
So how does this relate to the timing of my meals?
There are 3 main considerations when it comes to diet and our health:
1) how much we eat,
2) what we eat,
3) when we eat it...
Points #1 and #2 were covered by Rob and Aaron in the 2nd (click here) and 4th (click here) blog posts. However, in comparison to what we know about how much, and what we eat, we know relatively little about how meal timing influences our health - this is what my research is all about. Our meal timing can be considered in absolute (the actual time of day that we eat) and relative (compared to other meals) terms. Let me explain…
Absolute timing
Many important factors linked to our metabolism seem to depend on the time of the day. For example, if we eat a meal in the evening, our ability to control blood sugar is often worse compared to the same meal eaten in the morning. Another example is that our feelings of hunger seem to be lowest in the morning and peak in the evening. Rhythms in these processes makes sure our physiology is adjusted so that it can deal best with expected changes. Given that we have a tightly controlled body clock, it is unsurprising that eating at ‘unusual’ times (e.g. late or during the night) can be associated with an increase in the risk of high blood sugar levels and weight gain, because our body would not be expecting us to be eating at these times. This is especially true for people who regularly work night shifts, who seem to be at a greater risk of these conditions.
Generally speaking, sticking to a regular schedule of meals and sleep times is recommended for having a healthy body clock. Some new research suggests time-restricted eating (where you only eat during a 8-10 hour window each day) may also have health benefits. However, more research is needed in that area, for example with shift workers. On a slightly different note, exercise may also be beneficial for our body clock (but this is a story for another day…)
Relative timing
When we eat can also influence metabolism at subsequent meals. An effect of breakfast in this regard is associated with something called the second meal effect. Basically, eating breakfast can have a priming effect on our metabolism, so that our blood sugar and insulin levels in response to a second meal (e.g. lunch) are reduced when breakfast has been eaten compared to when breakfast is skipped. You can click here for more information about insulin. Having a better control of our blood sugar levels has been linked with good health outcomes (e.g. a lower cardiovascular disease risk) so this better control of blood sugar throughout the day by eating breakfast, may be beneficial for health. However, we need to explore whether regular breakfast skipping has long-term consequences on our body clock.
Take home message: The timing of our meals is often underappreciated compared to what we eat and how much we eat. However, the ability of our body clock to function properly is important for health. Maintaining a regular eating pattern and avoiding eating meals or snacking at unusual times should have benefits for your health.
Hopefully you enjoyed learning about your body clock and eating patterns today! Please subscribe to the blog (click here) for more information on diet, exercise, and healthy living!
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