Feeling sluggish at work? Hardly able to keep your eyes open during the day?

Maybe your diet needs a few changes to help you fight the constant fatigue. Before you reach for another cup of coffee, here are 7 foods to try out instead:

1. Lemon

While it can be difficult picturing anything other than coffee giving you that perfect energy boost in the morning, a glass of lemon water may be worth a try. Juice from one lemon can provide 40% of your daily requirement of vitamin C despite a relatively low-calorie intake.

Adding lemons to your diet can also boost your metabolism, prevent spikes in insulin, and provide enough potassium to help improve brain and nerve function.

2. Chia Seeds

"Chia seeds give you stable energy because of their great ratio of protein, fats, and fiber combined with the fact that they’re low-carb," said Dr. Carolyn Brown, a nutritionist at Foodtrainers in New York.

They also provide a feeling of fullness which can prevent you from overeating, a major reason why people can become sluggish long before bedtime.

3. Beans

For the best source of fiber, look no further than a meal rich in beans. The nutritional powerhouse can provide long-lasting energy without dips due to the blood sugar-stabilizing quality of fiber, according to the Nutrition Twins. Particularly for vegetarians and vegans, beans can be an essential alternative source of protein which is typically derived from red meat.

4. Spinach

Iron helps red blood cells in transporting oxygen to different parts of the body. As a result, fatigue is often caused by a deficiency of iron content. Leafy greens are considered one of the go-to foods for a quick iron boost. Spinach also contains magnesium, an important mineral for the energy process of the body.  

5. Eggs

A study from 2009 found eggs to be "a valuable food" for people who are undergoing endurance training and require all the extra energy they can get. Eggs were said to provide an essential amino acid which could improve the way muscles use glucose.

Eggs are also an excellent source of iron, protein, antioxidants, and numerous vitamins. Recently, a study found they can be consumed safely even by diabetics without increasing the cardiovascular risk.

6. Oatmeal

A breakfast combining the right amounts of proteins and carbohydrates can keep you energized and alert through the day, making oats a great choice to start with. "Oatmeal is one of the foods with the highest amount of soluble fiber. Soluble fiber stays in your stomach for hours, which also means that you have sustained energy for long periods of time," said Andy Bellatti, a nutritionist from Las Vegas.

7. Chocolate

Studies have shown that dark chocolates are a great source of antioxidants, improving mood as well as alertness. Reader's Digest recommends one square of dark chocolate as the perfect energy-boosting desert that stays on the safer side of calorie intake. It is also recommended that you opt for dark chocolate which contains a high concentration of cacao (at a minimum, 70 percent cacao) for maximum benefits.