There is a version of exam preparation that attends, with great seriousness, to past papers, mark schemes, and essay technique, while overlooking something considerably more basic: whether the student sitting down to work is properly fed.

It sounds almost too simple to merit discussion. In practice, it is one of the more reliably overlooked variables in a student's academic routine, and the evidence behind it is rather more substantial than the "superfoods" headline writers tend to suggest.

What the Research Actually Says

King's College London, in their guidance on eating for academic performance, make the point plainly: "what you eat affects how you feel." When it comes to a tutoring session or exam, you want a student who is alert, engaged, and not distracted by hunger. That is a low bar, but it is one that a surprising number of students fail to clear.

The KCL guidance recommends beginning the day with slow-release carbohydrates — porridge, whole-grain bread — combined with a source of protein such as eggs, yoghurt, or milk. The combination provides sustained energy rather than a brief spike followed by a slump, which is precisely what a focused, hour-long session requires. Skipping breakfast, the same guidance notes, has a demonstrable negative effect on exam performance. That finding extends naturally to any session requiring sustained concentration.

For foods with more specific cognitive benefits, the KCL research is worth quoting directly: researchers from King's Faculty of Life Sciences and Medicine found that eating a handful of wild blueberries a day improved memory. Oily fish, rich in omega-3 fatty acids, is recommended by the NHS twice weekly for brain function. Dark chocolate — at least 70% cocoa solids — has been shown in studies to improve blood flow to the brain, with positive effects on memory and mood. Leafy greens such as broccoli, spinach, and kale provide vitamin K, which supports cognitive function.

None of this is a quick fix, and it should not be presented as one. These are not supplements or performance enhancers; they are the kind of steady, unremarkable dietary habits that compound quietly over a term.

The Timing Question

King's College London also addresses something that parents of GCSE and A-Level students will recognise immediately: the post-lunch slump. As their guidance puts it, "a heavy meal can leave you feeling tired and low on energy." A tutoring session scheduled for 4pm after a large school lunch and nothing since is not an ideal arrangement.

The advice is to eat little and often on high-demand days, keeping blood sugar stable rather than allowing it to rise sharply and crash. Sugary snacks — biscuits, cakes, the kind of thing that tends to be within reach of a tired teenager — produce exactly this effect: a brief lift followed by fatigue and, as the KCL guidance wryly notes, "hanger" — the irritability that follows a blood sugar drop, driven by a rise in fight-or-flight hormones. Fruit, nuts, and Greek yoghurt are considerably better options for a pre-session snack.

For tutoring sessions that fall in the early evening, a light snack an hour beforehand is likely to be more effective than either a large meal immediately before or nothing at all since lunchtime.

Hydration

King's College London are clear on this too: "dehydration can make you feel tired and forgetful, as well as causing headaches." Water is the obvious solution, though fruit juice and tea count towards fluid intake. The guidance on caffeine is worth heeding: it is a stimulant, and reactions to it vary considerably between individuals. Increasing caffeine intake on the day of an important session or exam risks producing anxiety and shakiness rather than focus. A student who does not normally drink coffee is not well served by reaching for one an hour before a Maths paper.

A Note for Parents

The practical implication of all this is modest. It does not require a wholesale rethinking of mealtimes or a shopping list full of expensive supplements. It requires, roughly, that a student approaching a tutoring session has eaten something reasonable in the preceding two hours, that it was not a large heavy meal or a packet of biscuits, and that they have had enough water.

At Gravitas, our tutors are trained to notice when a student is flagging — and the causes are not always academic. A student who cannot concentrate is sometimes a student who has not eaten since noon. The fix, in those cases, is not a different pedagogical approach. It is a banana and a glass of water.

The fundamentals of good academic performance are rarely glamorous. They are, however, worth attending to.