Meal frequency and cognitive function

How we think, process information and behave can change day to day. What we eat and when we eat can have a big effect on how our brain performs. This means that structuring a healthy, stable diet with regular meals and snacks can help to promote an efficient workplace. Dietitian, Dave Shaw takes a look at the science of meals and effects of snacking on cognitive function.

Our brain is an energy demanding organ. Its main fuel is glucose (sugar) and despite it weighing only about 2% of our body weight, it can consume up to 20% of the energy available from glucose (1). This makes the brain one of the hungriest organs.  When we don’t provide the brain with enough fuel we often experience a major dip in mental function (2) - not a good thing when our job requires us to think, process information, problem solve and act quickly.

What and when we eat can have a major impact on our cognitive function. Eating foods lacking in nutrients, or skipping meals completely can be a common habit for busy people as during stressful moments, it can seem like the best option to delay or miss a meal. However, this move can prevent you from successfully accomplishing the task at hand.

Practise what you preach

We know it’s important for children to have breakfast before they go to school, take healthy snacks for breaks and a nutritious lunch - we tell them this frequently. It ensures they not only grow and develop to their full potential but are able to concentrate and mentally perform in class (2). As adults however, we rarely practice what we preach. Apply the same rules as an adult and continue to perform at your optimum.   

Eat frequently and improve your memory

Having breakfast and healthy snacks throughout the day can improve memory function, including the ability to recall snippets of information or images (2). Research concludes that meals and snacks high in carbohydrates provides the brain with glucose (it’s main source of fuel) for a period of time after eating. Meaning what you eat earlier in the day can have a significant impact to how you perform hours later. 

Focus on quality carbohydrates

Whilst carbohydrates can improve our brain function, it’s important to choose carbohydrate sources that are nutrient-dense and slow digesting. For example, carbohydrate options could include brown rice, quinoa, pumpkin, kumara or legumes. Healthy snack options could include fresh fruit and unsweetened yoghurt, nuts and natural yoghurt, or vegetable sticks and hummus. These food choices will help to regulate your blood sugar-levels throughout the day, leaving you with sustained levels of energy.

Drink plenty of water

Staying hydrated is hugely important when considering the implications to our brain function. When we don’t drink enough, we can quickly become lethargic and find it difficult to concentrate (3). While it’s not necessary to guzzle down litres every hour, it’s important to drink a glass of water regularly throughout the day. A practical way to keep hydrated is to keep a full water bottle on hand or glass of water at your desk if working in an office. Aim to refill your glass or bottle every hour or so.

A telling sign of your hydration level is the colour of your urine. Clear to cloudy urine is a sign you’re hydrated and yellow or brown colour urine is a common sign of dehydration. In addition to water, milk, herbal teas and other similar drinks can support your fluid intake requirements. 

Manage your caffeine intake

Time for a coffee break? It’s no secret that caffeine can improve our mental performance (4) however, too much caffeine can have the opposite effect and cause us to feel anxious, nervous, irritable and prevent us from having a good night’s sleep. Since everyone’s tolerance to caffeine is unique, how much you should personally have will vary. Finding your tolerance will help to remain focused, balanced and avoid any nasty side effects. Keep in mind that the effects of caffeine can last for up to 4 – 6 hours and beyond, so if you’re having several coffees or caffeinated beverages throughout the day, you may be going beyond your limit.

Generally, eating regular nutritious meals and snacks can help you stay on task, work efficiently and complete your work to a high standard. Just ensure you’re snacking on healthy foods and not overeating – it’s about balance.

Article written by Dave Shaw, Dietitian.  


1.     Mergenthaler P, Lindauer U, Dienel GA, Meisel A. Sugar for the brain: the role of glucose in physiological and pathological brain function. Trends Neurosci. 2013 Oct;36(10):587–97.

2.     Hoyland A, Lawton CL, Dye L. Acute effects of macronutrient manipulations on cognitive test performance in healthy young adults: A systematic research review. Neurosci Biobehav Rev. 2008;32(1):72–85.

3.     Wilson M, Morley JE. Impaired cognitive function and mental performance in mild dehydration. Eur J Clin Nutr. 2003 Dec;57:S24–9.

4.     Einöther SJL, Giesbrecht T. Caffeine as an attention enhancer: reviewing existing assumptions. Psychopharmacology. 2013 Jan;225(2):251–74.