6 Rules: How to Eat Right on the Job

By Gail Belsky for CBS MoneyWatch.com

Other than getting a good night's sleep, there's probably no other thing that impacts your productivity and mood at work more than what you eat. Yet you probably give little thought to what you consume before and during work, defaulting instead to what's convenient, cheap, and tasty. And when you do think twice about what you eat, it's usually in the context of a diet that's focused on losing weight rather than improving your cognitive functioning and energy levels. Fortunately, there are a few basic food rules that go a long way towards achieving these latter goals. Here are the best of them.

Things you will need:

• A new food attitude: Carbs are not the enemy. Neither is fat. Eliminating certain food groups may help your waistline, but it will hurt your brain functioning.
• A stash of snacks: To keep your brain well fueled, you can't let yourself get too hungry. Have a ready supply of trail mix, peanut-butter crackers, or Snickers bars at work. The combination of carbs and protein in these snacks will stabilize your blood sugar, fill you up, and keep you energized.
• Some willpower: Big meals actually reduce the supply of energy to your brain and leave you feeling sleepy for hours. Eat half of what you order, and take the rest home.

1. Balance What You Eat, Whenever You Eat

In 1956, the United States Department of Agriculture produced its "Basic Four" guide promoting the daily consumption of foods from four main groups - meat, dairy, grains, and vegetables. But today, nutritionists talk about a different set of food groups -proteins, carbohydrates (which produce glucose), fats, and fiber - and a different way to combine them. Instead of having a few helpings from each group every day, they recommend having something from each of the four groups every time you sit down to eat. And, yes, that includes carbs, which certain popular diets restrict. Why? Because the combination of carbs and protein (and to a lesser extent, fats and fiber) regulates your glucose levels and keeps your mood and mental ability on an even keel.

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Moreover, each food group brings unique brain-boosting benefits to the table. "Research suggests that meals with more protein and fats are associated with better-sustained attention, focus, and concentration," says Tufts research psychologist Kristen D'Anci. "Meals that have a higher carbohydrate content seem to be more calming and have fairly consistent positive effects with memory." Cut back on either group and you're missing half the benefits that food can offer.

2. Neglect Carbs at Your Own Peril

The research here is clear: Cutting carbs may shrink your waistline, but doing so will shrink your brainpower, too. "The popular low-carb and no-carb diets have the strongest potential for negative impact on thinking and cognition," says Tufts psychology professor Holly A. Taylor. In a 2008 study Taylor conducted, dieters who lowered their blood-sugar levels by cutting carbohydrates from their meals immediately performed worse on memory-based tasks than those who simply reduced total calories by the same amount. When they started eating carbs again, their memory skills quickly rebounded.

Brain cells require twice the amount of energy needed by other cells in your body because they never rest. And high-carb foods like pasta, bread, fruit, and rice produce the brain's favorite fuel - glucose. "Your brain only wants to burn glucose," says Shawn Talbott, a nutritional biochemist and author of A Guide to Understanding Dietary Supplements: Magic Bullets or Modern Snake Oil. It can burn protein if it has to, Talbott adds, "but it's like trying to run a gasoline engine on diesel."

If you are on a low-carb diet, we're not suggesting you go out and eat a loaf of Wonder Bread. There are plenty of "good" carbs (such as fruit, vegetables, and brown rice) that will supply your brain with all the fuel it needs.

3. Pack in the Protein

Proteins such as meat, fish, dairy, eggs, beans, and nuts slow the absorption of glucose so your brain gets a long and steady flow of fuel, rather than the brief blast you get from eating carbs and sugary foods (fats and fiber also help with this). And protein also brings its own set of brain boosters to the party. The amino acids found in meats, poultry, fish, and eggs help produce the neurotransmitters - serotonin, dopamine, and norepinephrine - that keep us focused, energetic, and upbeat.

Studies also suggest that certain minerals typically found in high-protein foods also enhance memory. A 2005 study by the U.S. Department of Agriculture found that adding zinc - found in meat, seafood, eggs, and milk - to the diets of middle-school kids improved their memories and attention spans. After receiving 20 milligrams of zinc a day, five days a week, for 10 to 12 weeks, their reaction time decreased by 12 percent, their word recognition rose 9 percent, and their ability to sustain attention on a task increased 6 percent.

4. Eat Smaller Amounts, and Eat More Frequently

If you want to keep up your energy and performance levels, the last thing you need is a three-course lunch (or a three-egg cheese omelet for breakfast). The same thing goes for big dinners if you're working late. Too much food - even if it's well balanced - is going to make you drowsy because it introduces too much glucose for your body to handle at one time. When that happens, your liver reacts by storing the glucose, and your brain actually gets less fuel than it needs. "If you eat too much, you're going to get sleepy, and there's really no way to recover from that," says Talbott. "Five to six small meals tend to make people perform much better than three squares."

5. Fat Is Beautiful ... for Your Brain

You probably know that omega-3 fatty acids are good for your heart. But they're great brain food, too. The fats found in salmon, walnuts, and kiwi improve learning and memory and help fight against mental disorders like depression, schizophrenia, and dementia, according to a 2008 report from the Brain Research Institute at UCLA. The fats support the synapses in the brain where much of our cognitive functioning occurs.

In addition to controlling your carb intake, portion and proportion play a big role in regulating glucose. Talbott recommends a highly sophisticated tool for measuring food amounts - your hand. Whether it's breakfast, lunch, or dinner, he says the portions are the same: "Your fist is the size of the carbs; your palm is the size of the protein. Make an OK sign with your thumb and index finger, and that's how much fat you should have. Open your hand as wide as it can go; that's the amount of fruits and vegetables. That's going to be a well-balanced mix."

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