Most of us have to watch our weight and what we eat. But there are some people who need to bulk up and increase their weight to maintain good health.

"You don't want to be filling up on burgers and fries," says naturopathic doctor Natasha Turner. "You want to talk about building muscle and gaining a little bit of fat but more so muscle mass. Safe weight gain is usually about 2-4 pounds per month."

According to Turner, you'll want to think about increasing your daily caloric intake by about 300-500 calories. You'll need to consider the amount of calories you burn at rest as well as how active you are, and adjust that number accordingly -- to a point where more calories are coming in then are getting burned away.

Nutrient-dense high calorie snacks
Nuts, such as cashews, walnuts and almonds are all healthy high-calorie snacks. Prunes topped with almond butter, Turner says, are sweet because of the natural sugar in the prunes, but a source of healthy fats can be found in the almond butter.

"To increase your weight, you increase your calories while monitoring your caloric burn," Turner explains. "However, you want to increase your calories with good sources of healthy fats, protein and carbohydrates."

Healthy fats
Avocadoes (a great source of potassium), almond butter (a healthy protein source) and olive oil are all good sources of healthy fats. The avocadoes are also a very satisfying snack, Turner said, and you can add them to sandwiches as a way to increase calories in your meals.

For more on healthy fats, read 9 great ways to add healthy fat to your diet.

Proteins
If you're trying to gain weight, Turner suggests that 2-3 of your daily snacks and all 3 meals should contain protein.

Omega-3 eggs, salmon, plain organic yogurt, chicken and turkey are all good sources of protein.

As far as red meat is concerned, she prefers organic beef and recommends eating lean beef no more than once or twice per week because it is higher in saturated fats.

Carbohydrates
Some higher glycemic index carbohydrates such as carrots, corn and potatoes, which are typically avoided by people trying to lose weight, are great for those trying to put on some pounds.