Fill up on fiber. Several studies shows its many benefits, potentially helping people live longer and with less inflammation. But eating fiber-rich foods, such as fruits and veggies and whole grains, plays a role in energy, too. Fiber helps the body slow the absorption of sugar, which will smooth out energy highs and lows, Dr. Namey says.

Pump iron. Iron helps your body build healthy red blood cells, which carry oxygen to the organs and muscles. When the brain, for example, isn't getting enough oxygen, you may not feel sharp and you may feel fatigued. Nonsteroidal anti-inflammatory drugs (NSAIDs), can cause low iron, as can having rheumatoid arthritis (RA). So get plenty of lean-protein, such as meat, poultry and fish, which are the best sources of iron.

Ask your doctor about vitamin B. You may benefit from a B vitamin supplement, as many seniors and people with RA are deficient in certain forms of this vitamin. B vitamins help the body convert carbohydrates into fuel, which is why being low in one or more may cause you to feel drained.

Drink plenty of water. "When you're even just a little bit dehydrated, your body isn't functioning properly," Sandon says. "You can feel fatigued." How much water should you get? That depends on you. Water needs vary considerably from person to person and most research suggests you use thirst as a sign you need to drink. But try to drink water to rehydrate. Avoid sugary drinks like sodas, Sandon says, as well as energy drinks, which may be high in sugar and caffeine.

Choose wisely at bedtime. Make sure the food you're eating isn't causing you to get less sleep. Spicy foods or high-fat foods, as well as orange juice and carbonated beverages can cause indigestion and heartburn. Avoid evening treats like chocolate that contain caffeine. And drinking alcohol may make you fall asleep faster, but alcohol can disrupt sleep, too.

Even perfect eating habits won't solve all your energy problems, Dr. Namey says. But adopting better practices may help you feel better and put some pep back in your step.