Diet diary: The persistent post-lunch lethargy

As the name suggests ‘postprandial’ refers to the meal and ‘somnolence’ to the strong desire for sleep.

Written by Ishi Khosla | Updated: September 10, 2016 1:09 pm
While sleepiness may not be confined to the middle of the day, studies report that it occurs predominantly after lunch. (Source: Thinkstock Images) While sleepiness may not be confined to the middle of the day, studies report that it occurs predominantly after lunch. (Source: Thinkstock Images)

Sitting at your desk at work and struggling to concentrate after lunch? You are not alone; it happens to the best of us. Welcome to ‘food coma’, that common sleepy, lethargic feeling after a meal that is also referred to as ‘carb coma’ or ‘postprandial somnolence’.

As the name suggests ‘postprandial’ refers to the meal and ‘somnolence’ to the strong desire for sleep. It may be accompanied by extreme fullness, bloating, mental fogginess, difficulty in concentration and reduced attention span.

While this sleepiness may not be confined to the middle of the day, studies report that it occurs predominantly after lunch. A study in the Journal of Applied Physiology, published in 1998, reported that the extent of postprandial somnolence was at its extent after meals eaten between 11 am and 2 pm.

What causes food coma? Food should not make us feel fatigued; in fact it should be the opposite, that is, we should feel energised. Increased sleepiness is thought to be caused by hormonal and neuro-chemical changes related to both quantity and type of food. The key is obviously in how much we eat and what we eat.

Some foods improve energy levels, while others may hinder it. Overeating results in foggy feeling and sluggishness. Food coma is often triggered by big meals and high carbohydrate and fat-rich meals. The bigger the meal, the easier it is to slip into a food coma.

High carbohydrate and high glycemic index foods like rice, bread, cakes, cookies, sweets, desserts, fruit juices can cause fluctuations in blood sugar levels. High glycemic foods rapidly break down into glucose, the simplest form of sugar in our body, causing a spike in blood sugar levels. This is followed by a spike in insulin levels (the hormone secreted by the pancreas) to bring down blood sugar levels as quickly. The rapid rise in insulin also causes our brain to produce a neuro-transmitter like serotonin and melatonin that leave us feeling drowsy and sleepy.

Food coma can also come independent of the composition of the meal, if it is large. The response to a larger volume in the digestive tract triggers a response to the nervous system to induce sleepiness. Sleepiness due to ‘food coma’ should not be confused with daytime sleepiness as seen in ‘sleep apnea’.

Fight the Fog

# Eat small frequent meals for a steady flow of energy and improving blood sugar metabolism. Practise portion control and avoid eating large meals.

# Choose the right kind of carbohydrates, protein and good fats in the right proportions. Good fats, protein and fibre are important as they delay the stomach emptying into the intestines, where absorption of nutrients takes place. These will help decrease and slow insulin response and keep you alert and active. Prefer whole grains and blended grains and limit intake of sugar, sweets, bakery, biscuits and sweetened beverages.

# Combine low glycemic index foods with the high glycemic index foods. Example: Combine pulses with cereals.

# Aim to fill most of your half plate with vegetables. Make sure 50% of the vegetables you consume are raw (salad).

# Take a short walk or stroll after your meal to improve insulin response to the meal.

Author is a clinical nutritionist and founder of www.theweightmonitor.com and Whole Foods India