We all know that secret stash of chocolate or third cup of coffee won’t do our bodies any good, yet when fatigue sets in, who doesn’t reach mindlessly (and with a good measure of guilt) for a quick pick-me-up? Turns out there’s a biological reason for your lack of willpower: Your body is declaring its need for energy. Fast.

“By definition, all foods provide energy, because calories are energy,” says Tara Gidus, RD, a dietician in Orlando, Florida. But the type of food you choose plays a huge role in how energized or lethargic you feel after you’ve digested it. While the body breaks all foods down into simple sugars, sweet and processed foods cause blood sugar to spike quickly (giving us immediate energy) and then dip (making us “crash” and leaving us looking for another boost). The key to avoiding those quick highs and longer lows? Choose foods that the body metabolizes slowly.

Here are six nutritionist-approved energy boosters that will keep your metabolism revved and have you feeling less drained throughout the day.

Oats
Carbohydrates may have gotten a bad rap in recent times, but they are actually an ideal source of quick energy thanks to the body’s ability to digest them almost immediately. But before you embrace buttered toast as your breakfast staple, remember that the most effective carbs come packed with fiber–like oats. Just a half cup of cooked oats provides a whopping four grams of dietary fiber, which takes a long time to digest and therefore slows the absorption of glucose into the bloodstream. The result? High, steady energy and a curbed appetite, says Gidus. Feeling dependent on the morning jolt you’ve come to expect from your sugary breakfast cereal? Add a little honey or molasses to your bowl of oatmeal; both of these nutrient-rich natural sweeteners provide a quick shot of energy. Paired with the slow-release energy from oats, this breakfast will give you the best shot at steering clear of a mid-morning slump.

Bananas
One of few fruits that contain both simple and complex carbohydrates, bananas deliver immediate energy and longer-lasting endurance. No wonder athletes rely on them. Easy-to-digest, potassium-rich bananas make a great snack before a big meeting or lunchtime power walk. To further slow down and extend the energy release this power fruit provides, spread some protein, like peanut butter or cottage cheese, on bite-size slices.

Bell peppers
Mixing these veggies in an omelet or salad does much more than add a colorful crunch: Bell peppers are a stellar source of vitamin C, which plays a key role in helping the body burn fat for energy. Vitamin C sparks the production of carnitine, a molecule that transports fat to the part of the cell where it’s metabolized, helping to burn more of it overall (and helping your metabolism stay revved and working as efficiently as possible).

Nuts
Nuts are a tasty little energy food thanks to their heart-healthy monounsaturated fat content, which gives them nine calories per gram (compared with four calories per gram in carbs and proteins). Research shows that eating monounsaturated and polyunsaturated fats, popularly known as “good fats,” instead of saturated and trans fats, slows the digestion of food, which keeps your metabolism firing and helps you feel full for longer periods of time. Plus, these good fats have also been shown to reduce the risk of diabetes, heart disease, and other illnesses. Just remember that a little goes a long way. To keep from overdoing it on this easy-to-pop snack, measure out your servings with a shot glass.

Green tea
Swap your afternoon coffee with a cup of green tea and you’ll get a post-lunch pick-me-up that won’t make you jittery for the rest of the day. Caffeine stimulates the sympathetic nervous system (the part responsible for our “fight or flight” response to danger) and can quickly boost alertness and performance, says William Evans, PhD, director of the nutrition, metabolism, and exercise laboratory at the University of Arkansas for Medical Sciences. Green tea delivers less caffeine than coffee, but it also contains another natural stimulant, theophylline, that has caffeine-like effects. The result? A boost that’s similar to what you get from coffee, minus the energy-sapping withdrawal. Just remember, any caffeinated food or beverage can cause dehydration, so keep chugging your body’s natural regulator–water–too.

Sweet potatoes
With chart-topping levels of vitamin A in the form of beta-carotene, sweet potatoes are loaded with important antioxidants, the body’s best defense against free radicals (which proliferate when we’re stressed or overly tired). Described by Gidus as “a nice package of very nutrient-dense food,” this root vegetable contains fewer than 100 calories, yet provides 28 grams of carbohydrates and more than 100 percent of your daily requirement of beta-carotene. Sweet potatoes are also an excellent source of vitamin C, and they’re full of fiber, vitamin B6, iron, and other nutrients, too.

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