One of the most challenging aspects of losing weight or avoiding weight gain is fighting the feelings of hunger that occur between meals and snacks.

Is there anything you can do to feel fuller for longer? Or do weight loss and maintenance just require putting up with feeling hungry now and then?

"In terms of how long you feel full after eating, satiety plays a big role," says Kylie Arrindell, a dietitian at Houston Methodist. "Satiety is defined as the state of being satisfied after a meal or snack."

This definition might not sound particularly complex, but how long you remain satisfied after eating — or put another way, how soon before you're hungry again — depends on a few things, including what you eat.

What is satiety?

"Satiety is feeling full from what you ate, meaning you're no longer noticing signs of hunger," says Arrindell. "But it's also influenced by whether you feel content with what you ate."

Arrindell says we're more satiated when our food is satisfying on a personal level, whether that's because of flavor or texture or both.

It's why we're so easily vulnerable to processed foods, which are literally manufactured to provide perfect bite after perfect bite. The catch is, it won't be long before you're hungry again after eating, say, a bag of chips, a reminder of the need to meet both criteria — feeling full and satisfied. (Related: Are Your Taste Buds Sabotaging You From Eating Healthier?)

How to feel full: It's more complicated than calories

To feel fuller longer between meals, you may need to make some adjustments to your diet or eating habits. But what matters most?

You might immediately think calories. The more calories you eat, the likelier you'll feel full, right? Not quite. Arrindell says that achieving satiety is more complicated than counting calories. (Related: Is a 2,000-Calorie Diet Healthy For Me?)

"I like to use the example of eating a 100-calorie orange versus drinking 100 calories of orange juice," says Arrindell. "You're going to feel full or more satisfied for longer after eating the orange, and you're going to get hungry pretty quickly after drinking the juice."

Why? There are a lot of reasons, actually.

Many different factors affect satiety, including:

• Hormone levels – particularly that of the hunger horomones, ghrelin and leptin
• Macronutrient composition – no, not all nutrients are created equal
• Volume of the meal – voluminous foods help physically signal your stomach is full
• Chewing – this physical act of eating is a satiety cue for your brain
• How quickly you eat a meal – eating slowly helps give your stomach time to signal to the brain once full
• Blood sugar spikes – because the resulting blood sugar crash can trick your brain into thinking you're already hungry again
• Behavioral responses to food – feeling content with a meal or snack can help signal satiety in the brain

Some of these factors are harder to control than others. For instance, the levels of hunger hormones and behavioral responses to food are influenced by their own slew of complex inputs.

"This is what makes injectable weight-loss medications so interesting," says Arrindell. "They target hunger on a hormonal level, suppressing your desire to eat for weight loss and maintenance purposes."

That said, there's plenty you can do to help yourself feel fuller for longer after a meal or snack.

"Macronutrient composition is very important," says Arrindell. "When nutritious, filling macronutrients are missing, you're not likely to feel satisfied for very long, meaning you're more likely to get hungry again shortly after."

Which foods help you feel full?

Like we said, satiety is complicated. But one factor we typically have control over is our food choices, which can have a big impact on how long it is before we feel hungry again.

"The macronutrients that take longer to digest are the ones that can help leave you feeling fuller for longer," says Arrindell.

We asked Arrindell to rank the macronutrients by the degree to which they help you feel full. Here's her list:

1. Proteins
2. Fiber-rich carbohydrates
3. Fats
4. Refined carbohydrates

"Protein is the macronutrient that will likely leave you feeling more sated, but fiber-rich carbohydrates — whole grains, beans, lentils, oatmeal, raspberries and even some vegetables like collard greens, kale and artichokes — are a close second," says Arrindell. "Refined carbohydrates are digested very quickly and leave you only temporarily satisfied."

As for fats, the healthy ones — monounsaturated and polyunsaturated fats — are nutritious and can still be filling, but they're also calorie dense. They should be eaten in moderation and aren't as likely to help you feel as full as most protein or fiber-rich foods can.

"And from a satiety perspective, combining protein and fiber together is even better," says Arrindell. "For instance, Greek yogurt topped with raspberries and almonds is a filling and healthy snack."

(Related: High-Fiber Foods: How to Get More Fiber In Your Diet)

You're most likely to feel hungry again sooner after eating processed foods, like baked goods, chips and even pasta and white rice, than you would after eating protein or fiber-rich foods.

Do some foods work against satiety?

In short, yes.

"Foods that are more calorie dense than nutrient dense aren't usually as helpful for satiety," says Arrindell. "They make us feel full in the moment, but they're lacking the nutrients that keep us feeling full and satisfied, so you tend to be hungrier sooner than expected."

Arrindell says most of these sorts of foods can be split into two categories: baked goods and vending machine options. Baked goods include things like cookies, cakes, pies, cinnamon rolls and packaged dessert items. Vending machine options are chips, pretzels, trail mix, sodas and the like.

Both categories typically lack the nutrients most likely to fill you up — protein, fiber and healthy fats. Instead, they're full of refined added sugars, refined carbohydrates, simple sugars and unhealthy fats, like saturated and trans fats.

"Refined carbohydrates can also lead to blood sugar spikes, which can work against satiety," says Arrindell. "Sometimes the body overcompensates and releases too much insulin to try to lower elevated blood sugars, and this is when you can end up with what's known as a sugar crash, when blood sugar levels subsequently drop really low. Your brain doesn't think it's getting enough fuel as a result, so it prompts hunger — even though it wasn't very long ago that you ate a meal or snack."

It's why blood sugar spikes can work against feeling full between meals, making it tougher to lose weight. They can also contribute to the development of insulin resistance and, eventually, type 2 diabetes.