Meal Timing – Why does when you eat matter?

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Many of us do not realise that ‘night owl’ lifestyles, shift work and exposure to artificial light are highly unnatural and can be detrimental to our health. The simple message is “it is not only what you eat and how much you eat, but also when you eat”. Let’s explore how energy intake at the wrong time can affect our body and metabolism. Firstly, we will cover some basic principles around circadian rhythms, which can help guide the optimum timing of our meals.

Circadian rhythms

Our brain-nervous system is the center to controlling our feeding-fasting schedule. The main circadian clock is located in a part of our brain called the suprachiasmatic nucleus (SCN). This little cluster of nerves, in essence, produces electrical rhythms which send regulatory signals throughout our body to control our metabolism, namely the feeding-fasting cycle, as well as our sleep-wake cycle and the release of certain hormones. The SCN is fed information coming from our eyes when we perceive light and darkness. And in turn the SCN will send information throughout the body to regulate our metabolism and hormonal functions.

Studies comparing different eating schedules indicate that an increase in weight is not only linked to food intake or exercise levels, but that the circadian-metabolic link is one of the main mechanisms responsible for weight regulation. The reason for this is still largely unknown, but we do know that a disruption in feeding and/or sleep schedules affects the gene expression of hormones controlling our metabolism. Unfortunately, our current modern lifestyle often makes it difficult to stick to regular eating and sleep patterns in line with our circadian clock, with shift workers, adolescents and young adults especially finding this difficult. However, this also means that any negative impact on our metabolism or overall health is reversible through diet and lifestyle changes in line with our circadian rhythms.

Putting it all together

The impact of circadian rhythms and diet is not fully yet known.  We do currently know that environmental factors such as light and darkness changes the information our brain sends to the rest of the body. This directly alters the levels of circulating hormones in our body, thereby affecting our appetite and weight regulation.  The negative effects of which are further compounded by poor lifestyle choices.

From what we do currently understand, when we eat can be just as important as what and how much we eat. Knowing this, we can make better decisions when it comes to when we consume our meals. Here are a few general tips on meal timing:

  • Eat a larger lunch and a smaller dinner meal (avoid big meals late into the evening).Aim to eat at least a few hours before bedtime and make this one of your smaller meals for the day..
  • If you’re a shift worker, you need to eat when you are most active and fast during the day (when you sleep), but don’t skip out on water!
  • When eating out, try and eat out earlier. This may mean booking a table for an hour before you plan on eating to allow time to order and for the meal itself to be prepared by the restaurant.
  • Snacking is okay, as long it doesn’t occur later in the day, thereby pushing meal times back.