That Sugar Movement


Oh my, food coma

170220_TSF_BlogHero_01We’ve all been there. The struggle is real. Food coma, otherwise known as postprandial somnolence, can drive a deep-rooted desire for a post-meal nap.

And to be honest, get in a quick 20-minute kip and you can be good to go for the rest of the afternoon!

However, the reality of having an arvo snooze for most is unlikely. So, what can we do to avoid a serious slump and keep on keeping on?

It may pay to consider how much and what it is you are eating.

Size matters

When it comes to how much you eat, size (of the meal) matters.

You’ve eaten a HEAP and your body requires a lot of energy to break this food down.

Food in the belly activates the parasympathetic nervous system (PSNS), one of two complementary branches of the autonomic nervous system (ANS). The PSNS oversees the ‘rest and digest’ activities, which is in contrast to the ‘fight or flight’ business commandeered by the sympathetic nervous system (SNS).

During the day the SNS is dominant, burning energy and keeping us alert and ready to act. Yet eating activates the PSNS, driving a preoccupation with resting and digesting. Though it is the size of the meal that matters.

“It’s got to be a large meal,” says David Levitsky, professor of nutrition and psychology at Cornell University. “The parasympathetic nervous system is activated when you eat, but (the extent to which it induces sleepiness) depends on the magnitude of the meal.”

A body’s natural circadian rhythm also has a role to play. The daily cycle of physiological processes works to the circadian body clock, including regulation of body temperature, blood pressure, secretion of digestive juices, and wakefulness and sleep. It may be we are wired to feel a little drowsy into the afternoon, regardless of what we have eaten for lunch.1-2

What it is matters

The type of foods can also impact whether we feel tired or not after a meal.

Protein and fat generally take longer to digest than carbohydrates. So, stick to smaller serves as when we overeat these, we are asking our body to deal with a meal over a longer period.3

Then we’ve carbs. Here are a couple of ideas for how carbs may contribute to the post-meal sleepy.

One: Complex, or whole food, carbohydrates are digested at a slow, steady rate due to a high fibre content. But foods comprising mostly refined carbohydrates and simple sugars, like heavily processed flours or added sugars, can be rapidly digested.

The glucose in foods like heavily refined flours or added sugars can then flood the system, and insulin is released to do its business of getting glucose out of the blood and into cells.

Insulin also helps with the transport of certain amino acids, the building blocks of protein. One amino acid insulin does not assist is tryptophan. So, more tryptophan is left in the system, and it is happy as it doesn’t need to compete with its amino acid buddies to be absorbed into the brain.

Tryptophan, in the brain, can be converted into serotonin, and serotonin into melatonin. These two chemicals – serotonin and melatonin – make us feel relaxed and sleepy.4-6

So, chowing down on a heap of sugar or refined carbohydrates may not be ideal for maintaining energy.

Two: Also consider this.

Eating a heap of added sugar or heavily processed and refined carbohydrate-rich foods, often a dramatic rise then dramatic drop in blood glucose and insulin follow. This dramatic drop can lead to symptoms like light-headedness, fatigue and slowed cognition.

So what do we do? Reach for a quick-sugary-hit pick-me-up! But this dose of the sweet stuff only continues the extreme rise and fall pattern, perpetuating the cycle for needing more sweets or simple carbohydrates to boost energy.

However, by ensuring any carbohydrates and sugars eaten are provided naturally within their original casing – like vegetables and fruit that are packaged with fibre – the absorption of sugars into the bloodstream is slow and steady, avoiding the sharp rise and fall of blood glucose and insulin.

What to do?

Here are some ideas on how to help you limit the post-meal drowsiness:

  • Eat smaller portions
  • Eat mostly real whole foods
  • Eat a combination of healthy fats, protein, and fibre from whole foods like vegetables or fruit
  • Eat slowly
  • Go for a walk after you’ve eaten
  • Drink water when feeling sluggish. Many of us mistake tiredness for thirst
  • In a bent over position, hang your head and let some blood flow toward the brain
  • Do your best to ensure a good night’s sleep. It can mean less need for a nap and less desire to reach for the sweet stuff.

By Angela Johnson (BHSc Nut. Med.)



  1. Harvard Health Publications 2009, Napping may not be such a no-no, viewed 16 February 2017, <>
  2. National Sleep Foundation n.d., Sleep drive and your body clock, viewed 16 February 2017, <>
  3. Youdim, A 2016, ‘Carbohydrates, Proteins, and Fats’, Merck Manual, viewed 14 February 2017, <,-proteins,-and-fats>
  4. Afaghi, A, O’Connor, H, & Chow, CM 2007, ‘High-glycemic-index carbohydrate meals shorten sleep onset’, The American Journal Of Clinical Nutrition, vol. 85, no. 2, pp. 426-430.
  5. Boado, RJ, Li, JY, Nagaya, M, Zhang, C, & Pardridge, WM 1999, ‘Selective expression of the large neutral amino acid transporter at the blood-brain barrier’, Proceedings Of The National Academy Of Sciences Of The United States Of America, vol. 96, no. 21, pp. 12079-12084.
  6. Wurtman, RJ, Wurtman, JJ, Regan, MM, McDermott, JM, Tsay, RH, & Breu, JJ 2003, ‘Effects of normal meals rich in carbohydrates or proteins on plasma tryptophan and tyrosine ratios’, The American Journal Of Clinical Nutrition, vol. 77, no. 1, pp. 128-132.
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