Behold the ultimate low-calorie food, the celery stick. Many would relegate this simple stalk to rabbits and dieters, but that would be a mistake. In addition to being one of nature's lowest-calorie foods at about 5 calories a stem, it packs a ton of nutrition.

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It's also thought that certain phytochemicals, called phthalides, found in celery may relax muscle tissue in artery walls, increase blood flow, and thereby help lower blood pressure. Here, 24 more surprisingly low-cal foods that offer big nutritional payoffs, based on information from The Men's Health Big Book of Food & Nutrition.

This article was originally published by our partners at RodaleWellness.com.

Incorporating low-calorie foods into your meals is a great way to increase the volume of your healthy breakfasts, lunches, and dinners without dramatically upping the calorie count. Filling low-calorie meals can also make a great diet for weight loss. (Exercise and sleep are important, too!)

The satisfaction point (not just calorie deficit) is key. "Consuming all low-calorie foods will keep your calorie count low, but likely will not keep you full and satisfied. This is not ideal because this will cause more hunger and usually leads to excessive snacking and possibly binge eating," explains Jessica Zinn, M.S., R.D.N., C.D.N., registered dietitian in New York.

Meet the Experts: Jessica Zinn, M.S., R.D.N., C.D.N., registered dietitian in NY; Diana Sugiuchi, R.D.N., a registered dietitian focusing on sustainable weight loss; Erin Palinski-Wade, R.D., a nutrition expert in NJ; Shana Spence, M.S., R.D.N., a registered dietitian nutritionist based in NY; and Jessica Levinson, M.S., R.D.N., C.D.N., culinary nutrition expert in Westchester, NY.

Look for foods that contain adequate protein and fiber, and pair lighter fare with a good source of healthy fats. When fiber, protein, and fat are consumed together, you will be fuller for longer, says Zinn.

Seek out whole foods (like fresh vegetables, fruits, and proteins) rather than processed ones (like shakes and supplements) for the biggest nutrition bang for your buck, says Diana Sugiuchi, R.D.N., a registered dietitian focusing on sustainable weight loss. Low-calorie whole foods not only slash the calorie count of your meal, but they're also an opportunity to pack in more nutrients.

So what should you add to your grocery list? Here are the best, low-calorie foods to help keep you full and fueled, according to dietitians.

Add cupfuls of this leafy green to salads, pastas, smoothies, and more without adding a ton of calories (there are less than 7 calories in one cup!). Spinach is also loaded with nutrients and antioxidants such as vitamin K, manganese, folate, and magnesium.

It's also a high-fiber pick, which may make meals more filling and may benefit your digestion.

Celery is one of nature's lowest-cal foods -- it has about 6 calories per stalk -- and it has a good amount of fiber, which is key for slowing digestion and helping you feel fuller for longer.

In order to enjoy the benefits of the fiber, enjoy it whole rather than juiced: "You get nothing unique by juicing celery, but you do lose the fiber," says Erin Palinski-Wade, R.D., a nutrition expert in NJ.

Looking for a low-calorie start to your day? Opt for oatmeal, which clocks in at just 83 calories per 1/2 cup, cooked. Oats are also a good source of carbs and fiber and contain more essential amino acids than other grains, making them a quality source of protein.

If your morning bowl doesn't quite fill you up, try stirring in half a cup of plain nonfat Greek yogurt, recommends Shana Spence, M.S., R.D.N., a registered dietitian nutritionist based in NY.

A favorite of Sugiuchi's during the colder months, Brussels sprouts can be enjoyed in so many ways. Try them raw in a salad, roasted as a side dish, or pan-fried with other veggies and tossed with pasta. They offer about 70 calories cup, and they're a great source of the all-important fiber and protein.

Low-fat cottage cheese has about one-fifth of the calories you'll find in most cheeses (163 calories per cup), and it's higher in protein, keeping your appetite in check for longer -- and your metabolism revved, Palinski-Wade says.

The type of protein found in cottage cheese, called casein, has been shown to facilitate muscle recovery when consumed before bed. Midnight snack, anyone?

Dark, leafy greens are definitely worth adding to your diet, Sugiuchi says. Although kale, which only has about 9 calories per cup, can be delicious raw in a salad, you don't have to go so crunchy; wilt it into pasta or soups for an iron-rich boost.

A single cup also offers over half of your daily value of vitamin K.

Research suggests that apples, which clocks in at about 100 calories each, are some of the best fruits for weight loss. In fact, one study found that whole apple or apple juice consumption over four to 12 weeks led overweight participants to lose weight. But, more research is warranted on this. Still, you know what they say about an apple a day!

Fish makes a great staple in weight-loss diets, Sugiuchi says, and flounder is one of the lowest-calorie fish out there (get just 109 calories per cooked fillet).

The Dietary Guidelines for Americans recommends that adults eat at least 8 ounces of seafood every week, so enjoy it alongside a healthy serving of vegetables for a nutrient-packed meal.

Try cucumber as a dipper in place of starchy crackers the next time you make a dip or spread -- a handful of your favorite chips will pale in comparison to an entire cucumber's 45 calories.

Swapping in cukes will also give you a boost of hydration as well as fiber, which can help with your digestive health.

Don't worry about the slightly elevated level of sugar in carrots: "They have tons of good vitamin A and lots of fiber, so eat up on those," Sugiuchi recommends.

Carrots clock in at just under 30 calories per carrot and yes, it's true that they support good vision: Their beta-carotene converts to vitamin A in the body, which is essential for eye health.

Shellfish are a diet-friendly protein option, with under 85 calories per serving. They're also great for bumping up your protein intake, meaning they'll leave you feeling fuller for longer, Sugiuchi says.

Shrimp is also one of the best sources of iodine, an important mineral that's necessary for proper thyroid function. But they do have a bit of cholesterol, so it's best to enjoy them in moderation.

Want to cut the calories in your sandwich or wrap? Swap your bread or tortilla for romaine lettuce (either by creating a lettuce wrap or simply chopping up your sandwich ingredients into a salad). One cup has just 8 calories, compared to around 100 calories per serving for the starchier options.

Lettuce is a good source of vitamin A and vitamin C, both of which are key for healthy skin.

Craving a crunchy snack? You could have a handful of potato chips for around 150 calories -- or a platter of sliced radishes topped with sea salt for just about 10 calories!

The spicy, cruciferous veggies are full of antioxidants like vitamin C, which helps battle free radicals and prevent cell damage.

Black beans are some of the lowest-calorie beans you can eat, at 109 calories per 1/2 cup. Better yet, they're also loaded with protein and fiber, a winning combo that can help stave off overeating, Spence explains.

Their fiber combined with a lack of cholesterol also makes them a heart-healthy choice, just look for varieties without added salt.

Poultry can pick up extra calories very quickly, but boneless, skinless chicken breast is actually low in calories when grilled (128 calories per serving), Sugiuchi notes. It's a weight-loss staple for a reason.

In addition to protein, chicken contains a high amount of selenium, a trace mineral necessary for immune function and thyroid health.

Asparagus -- which has less than 20 calories in half a cup -- is rich in insoluble fiber, which research suggests can thwart the release of hunger hormones and help keep your blood sugar stable. It also just happens to be one of the easiest sides to make (and eat).

Strawberries, which have about 50 calories per cup, are rich in a special type of fiber called pectin: "It can help slow digestion and allow you to feel fuller longer," Palinski-Wade explains. "It also slows the release of sugar into the bloodstream, helping to prevent hunger-triggering blood sugar spikes."

Melons like cantaloupe have a high water content, so they'll fill you up for very few calories, says Spence. Case in point? An entire cup of cantaloupe is just 54 calories.

Cantaloupe is full of the carotenoid beta-carotene, which gives the fruit its orange hue.

Zucchini (and its close cousin, yellow squash) has a super-low calorie count -- 27 calories per cup -- and loads of culinary potential. Don't be afraid to get creative (or go for seconds).

It contains an ample amount of vitamin A (about 40% of your daily value in one cup of cooked zucchini), which is great for eye health.

Cauliflower is a good source of vitamin C, potassium, and plant-based omega-3 fatty acids, and this versatile veggie can be used in place of higher-carb foods in some of your favorite dishes.

One cup of cooked cauliflower has just under 30 calories, and its mild taste can be seasoned in so many tasty ways. With a firm, hearty texture, it's main dish-worthy.

Not only is watermelon a great sweet treat to have on a hot day, it also boasts many benefits for your skin! And for just 46 calories per cup, this fruit is a great low-cal option for an afternoon snack.

Nuts can be considered low-calorie when eaten in moderation, Sugiuchi says -- so stick to the serving size. (For almonds, that's one ounce, or about 23 nuts, which contains 164 calories.) They're a great source of protein and healthy fats, but a little goes a long way.

One medium pear has 100 calories and 6 grams of satiating fiber, about 21% of the recommended daily value for fiber, says Jessica Levinson, M.S., R.D.N., C.D.N., a culinary nutrition expert in Westchester, New York. "The fiber is found in the skin, so be sure not to peel your pears before eating."

"In addition to enjoying pears as a snack, add them to salads, bake or poach them for dessert, or purée them to make pear sauce," Levinson suggests.

Pistachios are the only nut that is a complete protein and you get the most bang for your buck, says Levinson. "1 ounce of pistachios has 160 calories per 49 nuts, which is a larger portion size than other nuts." Research shows, she adds, that pistachio consumption is associated with increased fiber intake, decreased consumption of sweets, and reduced body weight.

When snacking on pistachios, choose in-shell pistachios when possible, suggests Levinson. "The process of taking them out of the shell will slow you down leaving you feeling more satiated." Try adding them to salads or chop them and use them in place of breadcrumbs as a coating for chicken or fish.

Along with having less than 100 calories, a typical container of non-fat plain Greek yogurt also has 14 grams of protein, so it will leave you feeling satisfied. "I recommend adding some berries for a bit of sweetness and fiber, while still keeping calorie count low," says Zinn.

Turkey jerky is another great low-calorie snack, with 60 calories per serving, specifically jerky sticks because they are single-serve and portable, says Zinn. They also have 6 grams of protein per serving which will help to keep you full for longer, she adds.

Like spinach and other leafy greens, arugula lets you go big on the serving size for very few calories (just 5 calories per cup). It's got a fresh, peppery flavor that shines in salads.

It offers about 15% of your daily value of vitamin K, which is important for blood clotting and bone health.

Craving dessert? These berries have a naturally sweet taste with very few calories (64 calories per cup) -- along with 8 grams of fiber. That's around a third of what you should get in an entire day.

Raspberries are also a great source of vitamin C, which plays an important role in immune function and improves the absorption of iron.

A large egg packs six grams of hunger-satisfying protein for just about 70 calories -- not a bad trade-off, if you ask us. Research shows that eggs can curb your calorie intake at your next meal, too.

In addition to their low-cal status, eggs are incredibly nutritious and contain a little bit of almost everything you need (vitamins, minerals, you name it). Omega-3 enriched and pasture-raised eggs tend to be even higher in nutrients.

Like oranges, they're a tasty, tangy treat. But unlike their larger cousins, each of these little citrus fruits has just 35 calories. Plus, fruit beats processed desserts by miles.

The snack-size treat is also loaded with vitamin C, clocking about 40% of your daily value in just one fruit.