We all love a good snack: Something to hold us over between breakfast and lunch. A quick pick-me-up when we hit that 3 p.m. slump. And, of course, dessert after dinner. If we don't choose the right types of snacks, though, these between-meal treats can cause us to pack on the pounds, feel sluggish and sick, and, ironically, develop cravings for more of the same.

But when done right, snacks can be a secret weapon against weight gain and unhealthy habits. Here's what you need to know about eating more, weighing less, and getting a handle on nutritious (and satisfying) snacking.

"Snacks can make or break your diet," says New York City-based nutritionist Rachel Meltzer Warren, R.D. "For most people, if you eat your meals three to five hours apart then you really don't need snacks to tide you over. But if you go for long stretches between meals -- or tend to feel ravenous when you get to dinner -- then eating a well-balanced snack can really help."

The right amount of calories in a snack depends on your daily caloric needs, how active you are, how often you snack, and how many calories you take in at each meal. But a good number to shoot for is probably between 150 and 300, says Meltzer Warren.

"The perfect snack has some carbs for quick energy, and some protein to keep you satisfied until your next meal," says Meltzer Warren. "Bonus points if you choose a snack with some fiber as well, since that will help you feel full and keep you from turning your snack into a fourth meal."

She suggests pairing foods like an apple or pear with a tablespoon of nut butter; some grapes with a bit of cheese; or a small yogurt with some whole-grain cereal sprinkled in.

Hundred-calorie snack packs are convenient and help prevent overeating, but they can still contain unhealthy food loaded with trans fats, preservatives, and high-fructose corn syrup -- not to mention, they use a lot of unnecessary packaging. (Plus, research has shown that people tend to eat more than one pack anyway, thus defeating their purpose!) 

Instead, make your own snacks from natural, whole foods whenever possible. Leftovers can be a great source of afternoon nibbles, but watch the portion sizes: Shoot for 1 ounce cheese; 2 to 3 ounces meat or fish; 3 or 4 pieces of dried fruit; or 1/4 cup nuts.

Several small meals or snacks throughout the day can keep your blood sugar stable and keep your metabolism running at its most efficient, which, in turn, can help keep your body from holding onto excess weight.

It can also keep you clearheaded and focused; you'll avoid that ravenous feeling between meals, or the "food coma" feeling that comes from stuffing yourself at lunch or dinner. (Which, incidentally, you'll be less likely to do if you've had a mid-morning or mid-afternoon snack.)

Figuring out your "hunger clock" will help you preempt strong cravings. What time do you start calculating the number of feet to the pizza place on the corner, or start feeling grumpy and distracted? If it's 11:30 a.m. and 4:30 p.m., plan your snacks for 11 and 4.

"For most people, it's the afternoon-into-evening time when things start to fall apart," says Keri Glassman, R.D., author of "The Snack Factor Diet." "If you are going to make just one change, add an afternoon snack." Timing your snacks will keep you clearheaded enough so that you don't succumb to the notion that Baby Ruths are good for you because they have nuts in them.

Many people deny their hunger and treat snacking as a naughty indulgence. When people are trying to avoid eating, they end up not eating as healthfully, says Glassman.

"They'll go for the vending machines or start eating out of a pretzel bag because they think it's not 'real eating.' Meanwhile, they've taken in 400 calories worth of pretzels when they could have had half a turkey sandwich for half the calories and been more satisfied. But in their minds, a turkey sandwich counts as real eating."

Mindlessly consuming liquid calories is one of the easiest ways to blow a healthy eating plan: An afternoon gourmet coffee drink or 20-ounce soda can be just as detrimental to your diet as a cupcake or a brownie -- and chances are, it's got little redeeming nutritional value.

Beverages can also play a positive role in your snacking strategy, however. Often, what you think is a hunger pang might just be a sign of thirst. Try sipping water with lemon or a cup of tea to see if your cravings subside. Green tea, in particular, may help rev your metabolism and help you burn calories more efficiently.

Even if you're pressed for time, you can still snack smart. Skip vending-machine fare and pick up a pack of nuts, wasabi peas, or dehydrated soybeans -- or pack carrot sticks and celery with a small container of hummus, baba ghanoush, or caponata.

"The right snack at the right time can do a lot of good," says Meltzer Warren. "I always recommend clients eat a smart snack before heading out to a wedding or another event where copious amounts of good food will be served. Doing so helps keep your hunger in check, which will keep you from overdosing on hors d'oeuvres."

It's also a good idea to always have something to eat before you go grocery shopping, she adds. "Food shopping hungry is a fast way to get all sorts of things you don't need in your cart!"

A vacation can set off a dietary bender that leaves you feeling greasy, lethargic, and a few pounds heavier by the time you return home: You're faced with different (often less healthy) food options, you're in a more indulgent mind-set, and your regular eating routine is totally off-schedule.

But planning ahead can help keep you relatively on track, so you can save your indulgences for those truly rewarding situations. Pack healthy snacks for airplane flights. Take a cooler along on road trips. And if you're staying in a hotel, request a refrigerator so you can store fresh fruit and vegetables.

Talk about a brain freeze: Scientists at the University of Texas Southwestern Medical School found that when animals were exposed to palmitic acid -- the saturated fat in ice cream and red meat -- fat molecules caused their brains to ignore appetite-suppressing signals from hormones leptin and insulin.

What this means is that the body doesn't realize it's full. So indulge mindfully, says study author Deborah Clegg, Ph.D. Since the fat will make you a poor judge of satiety, go easy on the mint-chocolate chip after dinner. Resist the urge to eat from the container -- or to go back for seconds.

In 2009, the American Heart Association recommended that women consume no more than six teaspoons of added sugar a day, and men no more than nine. The problem is, the average American downs about 22 a day. This doesn't include naturally occurring sugars in fruit and milk, but hidden white sugars -- in processed foods, sweetened drinks, peanut butter, some yogurts, and even salad dressings -- add up quickly.

These sugars appear to trigger a chemical reaction that creates inflammation in the body -- and too much inflammation can play a role in heart disease, cancer, and other major conditions.

Still, many of us are hooked on these added sugars. We crave sugary treats because they stimulate the brain's reward center and release pleasure chemicals, as alcohol and drugs do. For some of us, it may also be hereditary: Scientists have found tiny variations in our genes that may determine who develops a sweet tooth and who can pass up chocolate cake.

You can wean your body off sugar, however, by reducing your intake for two solid weeks. In that time, you'll start to reap the benefits: more energy, greater mental clarity, even better-fitting clothes.

Not all sugar is hidden; there's also the kind that beckons to us in the form of homemade brownies from coworkers, cupcakes for office celebrations, and doughnuts at breakfast meetings.

The workplace can be full of unhealthy snacks, and they can be hard to resist when they're such a part of office culture -- and when the workday becomes slow, monotonous, or stressful. But facing your relationship with these treats and learning to control your cravings can help you just say no to the sweets.

Got a hankering for the sweet stuff? It won't help to feed your craving with artificial sweeteners like saccharine or aspartame -- or the snack-food products now flavored with them. "We don't know the long-term effects of many artificial sweeteners," cautions Andrew Weil, M.D., author of "Healthy Aging."

Plus, some research suggests that they may actually cause us to eat more: A Purdue University study found that rats fed yogurt sweetened with saccharin consumed more calories and gained more weight than those who ate yogurt laced with sucrose.

Whether it's to quell anxiety or loneliness, to make up for insufficient calories during the day, or to fall asleep, overeating at night -- well after dinner is over -- is a common problem. At night, we're tired and want to relax. There's unstructured time, and fewer distractions to keep us from our emotions.

If you're prone to excess snacking after dinner, or if your habit evolves into a serious overeating problem (called Night-Eating Syndrome, or NES), treatments such as journaling, planning ahead, and changing your bedtime routine might help.

How you pack food into your fridge can have a real effect on your eating habits -- especially when it comes to snacking, when we tend to reach for whatever's visible.

Think of the top, eye-level shelf as your kitchen's primary fuel station: Place washed, dried, and cut-up fruits and raw vegetables in airtight containers on the top shelf. Berries are perishable, so rinse only before eating. Add a few hard-boiled eggs for a quick peel-and-eat protein boost. Consume all foods here within two or three days, and replenish.