Having plenty of zip to meet the demands of your job and personal life starts with your diet.

To maintain your energy level, your body breaks down the food you eat into glucose (a type of sugar)—the body’s main fuel—and sends a steady stream of it to your cells.

But here’s the trick: To feel good all day, your blood sugar needs to remain somewhat constant with minimal fluctuations. If your blood sugar drops too low, symptoms of hypoglycemia occur. Hypoglycemic symptoms may include: shakiness, nervousness, sweating, hunger, sleepiness, confusion, anxiety, dizziness, or weakness.

If you eat the wrong kinds of foods, your blood glucose can spike and drop, eventually causing the same symptoms.

With this in mind, here’s how to eat for all-day energy and keep your blood glucose level stable.

Don’t skip meals

Not eating meals is one of the fastest routes to low blood sugar. If you skip breakfast, your ability to concentrate will likely suffer all morning. Skip lunch, and by 3:00 pm your energy level and concentration will inevitably crash.

The reason: Your brain requires sugar in the form of glucose to function.

To keep your blood glucose from dipping, and thus zapping your physical and mental energy, always eat three meals or six smaller meals a day. In addition, don’t go more than four hours without eating something.

Balance meals

Make sure your meals include a mix of complex carbohydrates, such as grain products, fresh vegetables and fruit, beans, lentils and other legumes, protein, and some fat.

At breakfast, have waffles topped with fresh fruit (both are mostly carbohydrate) and a cup of low-fat or nonfat plain yogurt (a mix of protein, carbohydrate, and fat).

At lunch, have a turkey and cheese sandwich on whole-grain bread (this provides protein, fat, and carbohydrate) and vegetables such as carrot, green pepper, or celery sticks, or a piece of fruit (all of these are mostly carbohydrate).

Be sure to include carbohydrate, protein, and fat in all meals and snacks. Fat and protein slows the absorption of glucose and thereby causes the blood sugar to gradually rise.

On the other hand, if you eat only carbohydrates, such as fruit alone, your blood glucose level will rise and drop quickly, leaving you hungry and low on energy within an hour or two after you eat.

Similarly, if you just eat protein, the food may not be broken down fast enough to supply you with needed energy.

Snack smart

To counteract energy lulls you feel during the day, eat snacks that mix carbohydrates, protein, and fat.

Good energy-sustaining snacks include: low-fat plain yogurt with fresh fruit; cheese and crackers; an apple with peanut butter; low-fat cookies, such as graham crackers or gingersnaps, and a glass of skim milk.

If you experience an energy low that makes you feel shaky or keeps you from focusing on your work, opt for a carbohydrate-rich snack, such as a whole-grain breakfast bar, a glass of chocolate milk, or fruit juice.

Remember to keep your snacks light to ensure against unwanted weight gain.