Chrononutrition: Is When We Eat Just As Important As What We Eat? (Part 1.)

For those of you who follow me on Instagram (@jennahopenutrition) you’ll know that I recently went to a conference on meal timing and overall health. I shared a small amount of information from the conference but as so many of you had questions I’ve decided to write an article in more detail.


So, to start with what exactly is Chrononutrition? Chrononutrition is the relationship between our circadian rhythms (our body’s internal natural clock) and our dietary intakes. Realistically our body’s internal natural clock is always being interfered with by external environmental cues. This is referred to as our diurnal clock. These environmental cues include: light, meal times, sleep, exercise and social interaction to name a few but light having the greatest affect.

To some degree we can’t escape from these external cues but we can help to limit their impact through a consistent daily routine.


So now we have the background of our circadian and diurnal clocks let’s discuss the impact of nutrition and meal timings on these.

Below I’ve listed a few of the take home messages:

 1. Eat dinner at least 2.5 hours before you go to bed.

Eating later in the evening may affect your body’s ability to clear plasma TAG (fatty acids in the blood) and plasma glucose (sugar in the blood).

When fatty acids take longer to clear there is an increased risk of the production of low density lipoproteins (more commonly known as bad cholesterol). Fatty acids in the blood are normally increased at night so when you’re adding more to them by eating late you’re reducing the body’s metabolic control.

 So your next question is likely to be… So what time is the latest I should eat?

Like always we are all different and there is no set answer. Although, we know that ‘late owls’ e.g. people who truly can’t sleep before 1am can eat later as their melatonin (sleep hormone) isn’t released until later on in the evening. Alternatively if you’re anything like me (who needs to be in bed by 10pm) then you’ll need to eat earlier on in the evening before your melatonin in released. Ideally I’d suggest around 6-7pm.


2. Eat your carbohydrates earlier on in the day

So I have to be honest - the research in the past has been fairly conflicting. Before I get attacked and whilst this might not work for everyone, I’m here to share the research from the conference so here goes…

 Let’s chat carbohydrates for a second. Fruit, vegetables, legumes, beans, refined grains, whole grains and sugar all fall under the category of carbohydrates. When I’m talking about carbs here I’m referring to the type which will cause a greater spike in your blood sugar. This means the white kind; sugar and even particularly starchy vegetables such as sweet potato, pumpkin and parsnips which when cooked can cause greater spikes in blood sugar.

 So back to meal timings… It’s a similar picture when it comes to the sugars. Sugars take longer to clear from the blood at night. When this occurs regularly over a prolonged period of time there’s an increased risk of type 2 diabetes.

Interestingly research has shown that eating a high glycemic index dinner had a greater effect on blood sugar than a high glycemic index breakfast. In other words sugar has different effects on your blood sugar levels when consumed in the morning to the evening.

 More specifically carbohydrates consumed in the evening can create a greater blood sugar spike than those consumed in the morning.

 As a result it is advised that you eat your carbohydrates for earlier on in the day and consume a low GI meal in the evening. So what does this mean in practical terms?

 Rather than having a bowl of pasta or a pizza for dinner opt for some fish or meat and veggies, tofu stir-fry or lentil bolognaise over courgetti. Alternatively swap your white rice for brown or cauliflower rice to help lower the glycemic index of the meal.

Please note: this is not to suggest that carbohydrates are bad it’s simply to ask you to think about the time you might be consuming them especially if you’re having problems with your sleep.

porridge 2.jpg

3. Shift workers

Shift workers are an interesting group in the world of nutrition as their meal times, food choices and overall health often poses very different findings to those who are on regular working patterns. Research has found that shift workers have less interest in picking healthier food choices and consume more sugar and caffeine (although they may not be eating more calories). This may cause an increased risk in health related diseases. Although the good news is that if shifts have a predictable pattern it is possible to help improve overall health. Adaptation is easier as melatonin release may become more regular and predictable.

As there’s so much to say on this subject I’ve broken it into two sections so click here for part 2.