When mid-afternoon fatigue sets in, it’s easy to reach for a cup of coffee or a sweet treat for a quick boost. Unfortunately, the energy boosting effects are short-lived and often lead to a crash later in the day.

Instead, experts say it’s best to opt for a snack that’s rich in protein, fiber, and complex carbohydrates for a natural energy boost. Here are nine of the best options for energy-boosting snacks and meals that will keep you alert throughout the entire day.

Nuts. Almonds, pistachios, and other nuts contain important nutrients like magnesium and B vitamins which help convert food to energy. Pistachios have a powerful combination of protein, fiber and heart healthy monounsaturated fats, making them a great snack choice.

“Research shows that people with low magnesium levels tend to tire more quickly during exercise due to magnesium’s role in energy metabolism,” dietitian Rachel Berman says. A lack of B vitamins can cause fatigue, irritability and poor concentration. Berman suggests one serving, or about 23 nuts, to keep calories low.

Whole grains. “Thanks to fiber, whole grains help prevent the blood-sugar crashes that happen after consuming refined or simple carbohydrates,” says Berman. Whole-grain carbohydrates, like popcorn, are a great afternoon snack choice. The volume of popcorn also keeps you satisfied longer than chips or crackers. Try popping your own and adding herbs and spices, instead of butter and salt.

Nut butters. Peanut butter and almond butter can provide a great energy boost. They’re filled with health fats, protein and fiber, which help keep blood sugar levels stable. Berman says make sure you avoid brands with added sugars and stick to just a 2-tablespoon serving.

According to a study done at the University of Cambridge in England, protein also activates cells that help keep you awake. Researchers found that the cells responsible for our energy levels respond better to amino acids in proteins than in other nutrients.

Fish. Salmon is filled with omega-3 fatty acids, nutrients that can boost energy and mood. Berman says the nutrients found in fish have also been found to improve memory and reduce depression. The healthy fats found in fish like salmon also help lower blood pressure and bad cholesterol, making them heart healthy choices.

Bananas. These sweet treats are a great source of fiber, B vitamins, and potassium — nutrients that promote sustained energy. Bananas make for a great pre- and post-workout snack. Berman suggests a banana with a cup of yogurt for an energizing snack with fiber and protein for sustained energy.

Kale. This leafy green contains the amino acid L-tyrosine, which is great for an energy boost. The leafy green also contains fiber and a number of antioxidants which help stabilize blood sugar, says Berman.

Oatmeal. A dish of this high-fiber, filling breakfast staple can provides lasting energy all day long. Dieticians recommend looking for breakfast foods that contain at least 3 grams of fiber per serving. Options can include: oatmeal, whole-grain breads or pancakes, high-fiber breakfast cereals and quinoa.

Hummus. Made of garbanzo beans, sesame-based tahini, olive oil, and lemon, hummus is full of nutrients that contribute to high energy levels. The fiber and protein in the beans help stabilize blood sugar and boost energy. Use hummus as a veggie dip or a sandwich spread for a great snack or healthy lunch.

Greek yogurt. Compared to regular yogurt, Greek yogurt contains twice as much protein, making it a great breakfast or snack option. “The thick, indulgent texture is the perfect canvas for a variety of toppings that can make it even more substantial,” says dietitian Kari Kooi. Add fruit, nuts, or low-calorie granola to make it even more nutritious.