Law is built on brainpower – concentration, negotiation, precision. Yet many lawyers still try to sustain elite cognitive performance on caffeine, adrenaline and meals grabbed between meetings. Productivity and resilience are the metrics everyone hopes to optimise, but we rarely talk about the biology that underpins them — or how easily it becomes depleted.
As a former City lawyer and now a nutritionist, I’ve seen first-hand how the way we fuel the brain shapes performance far more than any time-management strategy ever could. Energy, clarity and emotional steadiness rely less on sheer grit than on physiology. And physiology can be supported.
This is the part of legal performance we don’t talk about, but we should.
The legal brain’s fuel – and how the workday sabotages it
The brain runs almost entirely on glucose — and lawyers burn through it fast. High-stakes decisions, drafting under pressure and hours of dense reading all demand a steady, reliable energy supply. Yet the typical legal workday doesn’t deliver that. A croissant for breakfast, a sandwich inhaled between calls, pastries with afternoon coffee: these patterns spike blood sugar, then send it crashing. And when blood sugar drops, so does cognitive performance.
The familiar 3pm crash follows — fading focus, irritability, fatigue. Instinctively, you reach for caffeine or sugar to rescue yourself, which triggers another spike, then another crash. It’s a kind of neurological whiplash that feels personal but is entirely physiological.
The alternative is surprisingly simple: pair carbohydrates with protein and healthy fats so energy releases more steadily. A proper breakfast, a more substantial lunch or even a smart snack is often enough to anchor the day. When blood sugar steadies, so does the brain.
Coffee plays its part too. Used intentionally, it sharpens concentration. Used to paper over exhaustion, it turns against you. Caffeine blocks adenosine — the body’s “time to rest” signal — giving you borrowed energy that later demands repayment in lighter sleep, harder crashes and heightened stress hormones. Small adjustments help: delay your first coffee, have it with food, set a cut-off time. Coffee should support clarity, not mask burnout.
Hydration is the quiet variable. Climate-controlled offices dehydrate you faster than you notice, and even mild dehydration affects memory, focus and mood. It often masquerades as hunger or distraction. A glass of water can restore more focus than a snack or a caffeine hit — an unglamorous but surprisingly effective reset.
Skipping meals, meanwhile, has become a professional badge of honour — a shorthand for productivity. But biologically, it backfires. Go too long without food and blood sugar drops; the body releases stress hormones to pull glucose from the liver. In the moment, the surge can feel like sharp focus. Over time, it drives irritability, fatigue and powerful evening cravings. That’s when the debt comes due: you’re far more likely to overeat, disrupt sleep and throw off appetite signals the next day. Regular meals aren’t indulgent. They keep the brain out of emergency mode.
Snacking, when done intentionally, becomes a tool rather than a trap. Ultra-processed snacks give you a hit, then a crash. Something with protein, fibre and healthy fats keeps you steady. A little planning helps: sliced apple with nut butter, oatcakes with hummus, Greek yogurt, a good-quality protein bar. Perfection isn’t the goal — staying out of the sugar-and-caffeine loop is.
And some days, the plan falls apart entirely. Meetings run long, emergencies land, a deal accelerates. When the day goes wrong, the aim stops being optimisation and becomes stabilisation. Eat something warm, drink water with your coffee, get a minute of fresh air. Small resets keep you functional when willpower is gone
Food as a professional skill
Nutrition is rarely framed as a performance tool in law, but it really ought to be: focus, clarity, emotional stability and decision-making are biological before they are behavioural.
High-quality work demands a high-functioning mind, and that depends on a well-fuelled body.