What to Eat Before and During the Exam

A 2012 study published in Appetite found that students who ate breakfast before a cognitive test outperformed those who skipped it — but the type of breakfast mattered almost as much as eating at all. High-sugar breakfasts produced a short performance window followed by a drop-off, while lower-glycemic meals sustained attention longer. That's worth keeping in mind on test day, when you need your focus to hold for two to three hours, not just the first twenty minutes.

What to Eat Before the Exam

The general advice that holds up across nutrition research is straightforward: combine a moderate amount of protein with slow-digesting carbohydrates, and eat roughly 90 minutes before your exam starts. That window gives your body time to digest without leaving you hungry mid-test. Eating right before you sit down can pull blood flow toward digestion and away from concentration — an uncomfortable feeling most people recognize but don't always connect to what they ate.

• Eggs and whole-grain toast — protein plus complex carbs, easy to prepare, widely tolerated
• Oatmeal with a banana — slow-releasing carbohydrates, potassium, and enough fiber to avoid a glucose spike
• Greek yogurt with berries — works well for some people, but see the dairy note below
• Nut butter on whole-grain bread — a reasonable option if you're not a breakfast person and need something quick

What to avoid is just as important. A pastry or sugary cereal will spike your blood glucose and then drop it, often right around the time you hit the hardest section. A heavy meal — think a full diner breakfast — can leave you sluggish and physically uncomfortable. If you're uncertain about how dairy sits with you under stress, skip it on test day. Gut responses can amplify under anxiety, and the digital SAT or section-adaptive GRE isn't the moment to experiment.

Caffeine: Useful, But Easy to Misuse

Caffeine does improve alertness and reaction time at moderate doses — roughly 100–200 mg, or about one cup of coffee. The research on this is reasonably consistent. The problems come with overdoing it. High caffeine intake increases anxiety, can cause jitteriness and a racing heart, and often produces a crash that hits during the second half of a long exam. If you already drink coffee daily, your usual amount is probably fine. If you don't drink caffeine regularly, test day is not the time to start — you'll be unaccustomed to the effect, and the combination of exam stress plus stimulant can make anxiety worse, not better. Energy drinks that pair caffeine with high sugar are worth avoiding for the same reasons as sugary food generally.

During the Exam

Most standardized tests allow water at your seat, and you should use it. Mild dehydration — even at levels before you feel thirsty — has been shown in several studies to impair short-term memory and concentration. Keep a water bottle accessible and sip throughout rather than waiting until you notice thirst.

If your exam includes a scheduled break (the digital SAT has a ten-minute break between sections; the GRE has a ten-minute break after the third section), use it to eat something small. A mixed nut and dried fruit bar, a small handful of nuts, or a piece of fruit works well. You want calories and a little protein without anything that takes time to digest or leaves you feeling heavy going back in. Avoid anything high in refined sugar — that mid-exam energy boost tends to peak and drop faster than you'd like.

One Honest Caveat

Individual responses to food vary more than nutrition articles typically admit. Some people genuinely perform better on a lighter stomach. Others need a full breakfast or their focus suffers. If you have several weeks before your exam, it's worth doing a practice session under realistic conditions — eating the breakfast you're planning and noting how you feel two hours in. That real-world trial tells you more than any general recommendation, including this one.

For a practical next step: plan your test-day breakfast now, before the week gets busy. Pick one of the combinations above, make sure you have the ingredients, and do a dry run on a practice test day. Small logistics done in advance are one less thing to think about when the morning actually comes.