Having energy throughout the day is, for many, like chasing after the elusive white rabbit. Just when you think you've got it, after a cup of coffee and a morning sweet roll, for instance, it slips away and feels as though it was never even there.

Whether struggling with energy ups and downs or, worse, feeling tired all the time, a lack of energy is a real drain on your work and social life. In fact, close to one-third of respondents to the 2005 National Sleep Foundation poll said they have missed work or other events, or made errors at work, because of being too sleepy. Another 23 percent said their intimate or sexual relationship had been negatively affected because of being too tired.

Of course, many factors contribute to your level of energy but one of the most influential is what kinds of food you put in your body. Overall, a healthy diet with fresh, minimally processed foods will give you drastically more energy than a diet of mostly processed food.

Specifically, adding the following eight foods to your diet will rev up your energy and help keep you from yawning at 10 a.m., feeling your eyelids get heavy at 1 p.m., and nodding off during your afternoon meeting at 4 p.m.--and they taste great too. (NOTE: Eating the certified organic versions of these foods will increase their energy-boosting power even more.)

1. Lean Beef or Chicken (ideally free-ranged)
Adding a little protein to every meal is essential to keep your organs functioning and your energy levels up. Lean protein also contains tyrosine, an amino acid that helps your brain produce the chemicals norepinephrine and dopamine, which improve your mental function. Turkey, pork tenderloin, eggs, shellfish and sardines also contain tyrosine.

2. Black Beans
Complex carbohydrates like those in black beans and other legumes help keep your blood sugar levels balanced throughout the day, providing a steady, slow-burning source of energy to make you feel awake. Plus, black beans are a rich source of iron, an integral part of hemoglobin, which transports oxygen in the body, and key enzyme systems for energy production and metabolism.

3. Seaweed
Seaweeds like kelp, wakame, arame and dulse can be found in Asian grocery stores and health food stores. It can be eaten dried, straight out of the bag, or added to soups, salads and vegetables. Seaweed contains the broadest range of minerals of any food--the same minerals found in the ocean and in human blood. It also contains pantothenic acid and riboflavin--two B-vitamins needed for your body to produce energy.

4. Almonds
These tasty nuts are rich in manganese and copper, both of which are essential cofactors of an enzyme called superoxide dismutase. This enzyme helps keep energy flowing by inhibiting free radicals inside cells' mitochondria (the energy-producing area of cells). Plus, they also contain riboflavin, another important component of energy production.

5. Water
We know, it's not really a food, but it's so important that we decided to include it anyway. Water is necessary for your body to produce energy, including digesting, absorbing and transporting nutrients. If you don't drink enough of it, your cells will be less able to receive the nutrients they need for energy, leaving you feeling sluggish. If plain water doesn't appeal to you, try spicing it up with a squeeze of lemon, lime or other citrus.

6. Cantaloupe
This melon is an exceptional energy food because of its combination of vitamin B6, dietary fiber, folate, and niacin (vitamin B3). The B vitamins (necessary for the body to process sugars and carbs) combined with fiber (which helps the sugars be distributed gradually) support energy production by keeping blood sugar levels stable.

7. Kiwi
This tiny fruit often gets overlooked in favor of the more common apple or orange, but it packs a powerful punch. With more vitamin C than an equal amount of orange, it's a potent energy-boosting food. When vitamin C levels are depleted, people often feel tired. One study found that women with low vitamin C levels felt more energized after receiving vitamin C daily. "They felt better and they had more energy," said Carol Johnston, PhD, assistant professor of food and nutrition in the family resources department at Arizona State University. Other foods rich in vitamin C include raw red or green pepper, broccoli, strawberries and Brussels sprouts.

8. Oatmeal
This morning favorite is loaded with soluble fiber, a key to slowing down carbohydrate absorption and keeping blood sugar levels steady. "A fiber-packed whole grain cereal, oatmeal is your best breakfast choice for long-lasting energy," says William Evans, PhD, director of the nutrition, metabolism, and exercise laboratory at the University of Arkansas for Medical Sciences/Veterans Affairs Medical Center.