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Having healthy snacks at work will prevent you from reaching for the cookie tray in meetings or junk food lying around the office.

If you struggle to keep up with work deadlines, meetings and endless e-mails, your diet may be to blame, at least in part. And it may play a larger role than you realize.

The foods you eat – and don't eat – have a direct impact on how productive you are.

According to a 2012 study conducted with nearly 20,000 employees who worked at three large U.S. companies, those who ate an unhealthy diet were 66 per cent more likely to report productivity loss compared with their co-workers who ate whole grains, fruits and vegetables.

Here's something to consider when deciding what to grab for lunch at the food court: The wrong choice can do more than deliver too many calories – it can derail the rest of your workday.

Nutrition and cognitive performance

Your diet can affect your mental effectiveness in a number of ways.

Carbohydrate-rich foods (e.g., grains, fruit, legumes) are metabolized into glucose, the main source of fuel your brain relies on to keep you feeling alert and focused. Problem solving, concentration, learning and memory are closely tied to how efficiently your brain uses glucose.

Glucose is also needed to synthesize neurotransmitters, brain chemicals that communicate information throughout the brain and body. Without enough glucose, communication between brain cells is impaired.

Your brain needs more than glucose, though. Numerous vitamins and minerals are needed to generate energy in the brain, synthesize neurotransmitters and fend off free-radical damage.

A nutrient-poor diet can also impede your body's ability to combat stress. That's because its physiological stress response requires many nutrients including carbohydrate, protein, B vitamins, vitamin C, magnesium and selenium.

Your eating habits can affect your mood, too. A growing number of studies suggest that an unhealthy dietary pattern – a higher intake of saturated fat, sugar, refined starches and processed foods – increases the likelihood of depression and anxiety, while a healthy diet reduces the risk.

What to eat to get more done at work

To perform optimally at work, you need to make intelligent food decisions during the day. The following six strategies will help improve the way you think and work.

Choose the right fuel. To ensure your brain gets much-needed glucose, include carbohydrate-rich foods at meals and snacks. While bread, cereal, rice, pasta, lentils and fruit are all good sources of carbohydrates, not all supply your brain with sustained energy.

High-glycemic foods such as white bread, white rice, refined breakfast cereal, sugary drinks and sweets release their glucose quickly. A rapid energy burst is followed by a drop in blood sugar, causing you to lose steam faster. You'll also feel hungry sooner, a feeling that can wreak havoc on your ability to focus.

Low-glycemic carbohydrates, on the other hand, are converted to glucose more slowly and provide your brain with sustained energy. Good sources include 100-per-cent whole-grain rye bread, oats, brown rice, quinoa, sweet potato, whole-grain pasta, yogurt, milk, soy milk, beans and lentils, and most types of fruit.

Include protein. Balance meals and snacks with a source of protein such as chicken, tuna, eggs, lean meat, tofu, nuts or Greek yogurt. Doing so will slow down digestion, helping to sustain your energy – and curb hunger – longer after eating.

Protein in a meal can also stimulate the activity of certain brain cells that cause alertness.

Eat at strategic times. Since your blood glucose drops two to four hours after eating a mixed meal, eat every three hours to keep your energy level constant and to prevent hunger. Skipping meals and/or snacks to fit in more work time will undermine your productivity.

If you need to block off time in your busy calendar to eat lunch, do so. If it will help, set an alert to remind you to eat a midafternoon snack.

Bring your snacks to work (lunch, too, if you can). Having healthy snacks at work will prevent you from reaching for the cookie tray in meetings or junk food lying around the office.

Carbohydrate- and protein-rich snacks include nuts and dried fruit, an apple with an ounce of cheese, a hard-boiled egg with whole-grain crackers, raw vegetables and hummus and energy bars made with whole-food ingredients.

If fruit smoothies are your go-to breakfast, make extra to bring in a S'well bottle for a midday snack. (It will stay cold all day.)

Ditto for protein shakes (include fruit in your shake for carbohydrates).

Include fruit and vegetables. There's another reason, beyond brain energy, to bring fruit and veggies to work. Doing so can enhance your creativity.

A 2015 study conducted in 405 adults, published in the British Journal of Health Psychology, found that participants with higher intakes of fruit and vegetables throughout the day reported feeling happier and more creative at work than people who ate less of them.

The researchers speculate that vitamins, antioxidants and carbohydrates in fruit and vegetables increase the brain's production of dopamine and serotonin, neurotransmitters involved in mood, behaviour and cognition.

Reach for brain-friendly foods. In addition to fruit and vegetables, other foods help your brain perform well by supplying nutrients and phytochemicals that keep inflammation and oxidation in check.

Make a salmon (omega-3s) sandwich, toss lentils or black beans (folate) into a green salad, include walnuts (flavonoids) in your trail mix or blend avocado or almond butter (monounsaturated fat) in your smoothie, for example.

Hydrate wisely. Keep a bottle of water at your desk and sip on it during the day. Research suggests that even minor dehydration can impair your ability to perform tasks that require attention, memory and psychomotor (brain-muscle) skills.

Drinking one or two small cups of coffee is fine; caffeine can enhance mental alertness. But drinking too much coffee during the day can keep your brain stimulated at bedtime. (It takes about six hours for half the caffeine you consume to be eliminated from your body.)

To cut back on caffeine, switch to decaf coffee or green or black tea, which both have considerably less caffeine than regular coffee.

Leslie Beck, a registered dietitian, is based at the Medisys clinic in Toronto.

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