Want to feel more alert? To keep up your mental energy and focus, you’ve got to eat the right foods, at the right time.

A client recently complained that she suffered from ‘brain fog’. “My mental energy is shot and I can’t focus.” So she wondered…“is it something I’m eating?” Possibly. But more likely, it’s what she’s not eating that’s leaving her mental energy flagging. As a full-time student and a new mom, her eating patterns are erratic and she’s often grabbing something on the run, and relies on coffee to keep her going. Without the right foods to give her brain the fuel it needs, she can’t possibly expect to keep her mental energy in high gear.

The next time your mental energy is fading and you feel like you can’t string two sentences together, think back. When did you last eat? What did you have? Have you been drinking enough liquids? Skipped meals, unbalanced meals, and dehydration can all zap your mental energy and focus. (And don’t forget that getting adequate sleep and rest is part of the equation, too).

How what you eat affects your mental energy
What is mental energy, anyway? It’s actually got several features – including your overall mood, your motivation, as well as your attention and focus. When your mental engine is revved up, there’s a good chance your diet had something to do with it. So, here’s some “food for thought”.

What to eat to keep your mental energy up all day long
• Carbs fuel your brain Glucose is the only fuel that normally feeds your brain cells – and it’s derived from the carbohydrates in your diet. After they’re broken down during the digestive process, carbohydrates enter the bloodstream as glucose (your ‘blood sugar’). Since your brain is active 24/7, it has high energy demands – higher, in fact, than any other cells in your body. And, since brain cells – the neurons – can’t store glucose, your brain needs a continuous supply. Stick with the healthy carbs – fruits, vegetables and whole grains – to give your brain the fuel it craves. These high fiber foods take time to digest, which leads to a gradual release of glucose into your system. On the other hand, a meal high in refined carbohydrates – think starchy, sugary foods – can actually backfire on you. Since these foods are digested relatively quickly, you may experience a quick rise in your blood sugar… often followed by a quick drop. And that blood sugar ‘crash’ can make you feel mentally sluggish.

• Your brain wants fuel at regular intervals
Since your brain wants a steady source of glucose, it’s important to eat at regular intervals throughout the day to keep your mental energy from taking a nosedive. Aim for small meals and snacks every 3-4 hours.

• Your brain wants breakfast There’s plenty to be said about the importance of breakfast, and giving your brain a boost is just another reason to fuel up first thing. While you were sleeping, your brain was plenty busy – and it burned through lots of fuel overnight – and the tank is pretty empty by morning. Do your brain a favor and start your day with a well-balanced breakfast that includes both healthy carbohydrates and a shot of protein.

• The best proteins for your brain
Even though your brain doesn’t use protein directly for fuel, it does use amino acids – derived from the proteins that you eat – to manufacture important brain chemicals. Tyrosine, for example, is an amino acid (found in poultry, fish, dairy products, nuts and beans) that your body uses to make a brain chemical called dopamine that promotes alertness and brain activity. Another amino acid, called tryptophan (also found in seafood, poultry, dairy products and soybeans), is needed to make another brain chemical called serotonin, which leads to feelings of calmness and contentment.

• The best beverages for the brain
When your body is dehydrated, it can affect your mood and your energy level. Mild dehydration reduces alertness and your ability to concentrate, and by the time you feel thirsty, your mental energy has already taken a hit. Water is always a good choice, but coffee and tea in moderation are fine, too. Caffeine-containing beverages may help with focus and concentration – but be smart about it. You don’t want to ignore your diet and simply rely on caffeine to keep you going through the day. You need to hydrate properly and eat right. And, monitor your own response to the caffeine you’re taking in. If it makes you jittery or keeps you up at night, you’d be wise to cut back. Using caffeine for a brain boost during the day won’t do you much good if it interferes with a good night’s sleep.

Susan Bowerman, M.S., R.D., C.S.S.D., F.A.N.D. – Director, Worldwide Nutrition Trainingat Herbalife. Susan is a Registered Dietitian and a Board-Certified Specialist in Sports Dietetics.