If you've never tried brown rice before, get used to the taste by mixing it with white rice.

Spinach

A can of spinach was always on the menu when Popeye had to fight the bad guys. He knew how much energy spinach provided years before scientists did.

This green, leafy vegetable contains compounds called nitrates. Nitrates boost the powerhouses in cells which provide energy. These powerhouses, called mitochondria, fuel the activity and growth of body cells. A single portion of spinach is enough to increase the efficiency of these powerhouses.

Spinach is also an excellent source of iron. This mineral helps to carry oxygen from the lungs to the muscles and other parts of the body. Your body has to have enough iron to keep energy levels constant. If iron levels are low, oxygen circulates much more slowly. If you are deficient in iron, you will have low energy levels and feel tired and lethargic.

Try sprinkling baby spinach leaves in soup, noodles or on top of omelettes.

Oats

Whole oats (not instant oats or oatmeal) are rich in complex carbohydrates and fibre. They are also high in energy-boosting B vitamins and have a low glycaemic index (GI). The GI ranks carbohydrates according to their effect on blood glucose levels. Carbs with a high GI are broken down easily during digestion, allowing glucose to enter the bloodstream quickly. High GI foods include white bread, cornflakes, white rice, honey, fruit juices and sports drinks. Low GI foods like whole oats, however, are broken down much more slowly and provide a continuous and sustained supply of energy.

A bowl of steaming hot oats topped with mixed berries makes a wonderful start to the day during the cold winter months.

Quinoa

Quinoa (pronounced keen-wah) looks like a grain and tastes like a grain but the tiny yellow 'grains' are in fact seeds. Quinoa comes from a leafy plant native to South America. These seeds are nutrient powerhouses and contain more protein than other grains.

Unlike other vegetable proteins, the proteins in quinoa are complete. This means that quinoa contains all the essential amino acids our body needs but can't make. Legend has it that Inca armies used to make 'war balls' from quinoa and fat. This mixture provided the armies with enough sustainable energy to help them march for many days.

Quinoa is rich in fibre and contains essential energy-sustaining vitamins and minerals such as vitamins E, B1, B2 and iron. It is so nutritious that the US space agency Nasa is even thinking about growing it in space.

Quinoa is easy to prepare. All you need to do is rinse it in water, drain and then cook it in water for 15 minutes.

Red lentils

Red lentils are great energy boosters: the higher fibre content ensures that the sugars in them are released slowly into your bloodstream. This results in an even supply of energy rather than the quick spike and crash associated with biscuits, cakes or sweets.

The protein in lentils is filling, and the complex carbs in them provide a great source of slow-burning fuel. Red lentils are also rich in a mineral called molybdenum which is needed for maintaining energy levels.

Red lentils work well in stews, soups, salads and curries.

And don't forget to hydrate

Our bodies are very sensitive to the loss of water. Dehydration will zap you of energy and make you feel lethargic.

Keep up your energy levels by drinking at least eight glasses of water daily - more in hot and humid weather. Don't wait until you're thirsty before grabbing your water bottle. Keep a bottle handy at your desk and in your bag and take regular sips throughout the day.

Test your energy IQ with this quiz

1 An afternoon nap is great for boosting your energy levels. What is the best length of time for a catnap?

a. 10 minutes

b. 20 minutes

c. 40 minutes

d. 60 minutes

2 Not getting enough sleep can be energy-draining. How many hours of sleep do teenagers need every night?

a. 7-8 hours

b. 8-9 hours

c. 9-10 hours

d. 10-11 hours

3 Exercise can boost your energy levels. When is the worst time to exercise?

a. first thing in the morning

b. mid-afternoon after school

c. early evening before dinner

d. last thing at night before you go to sleep

4 Low GI foods give a continuous supply of energy. Which of the following is NOT a low GI food?

a. new potatoes

b. mashed potatoes

c. sweet potatoes

d. baked potatoes

5 Which of the following foods is NOT rich in iron?

a. beef

b. egg yolks

c. milk

d. dried apricots

Answers: 1. a, 2. c, 3. d, 4. b, 5. c