Being too skinny can leave you feeling low on energy and self-conscious about your appearance. A high-calorie diet, strength training and light cardiovascular exercise can help you add pounds in the form of muscle, so you're the strongest, fittest and healthiest you can be. Resist the urge to eat just anything, as too much sugar and saturated fat can still leave you vulnerable to heart disease, stroke, type 2 diabetes and cancer, regardless of your body size. Eat more healthy, calorie-dense foods from all the major food groups and add calories to meals with healthy unsaturated fats.
Weight Gain Is About Calories
If your body mass index is less than 18.5, you're considered underweight. Whether your underweight status is due to a high metabolism, malnutrition, surgery or illness, you'll need a calorie surplus to put on pounds. Gaining a lot of weight quickly can lead to excess body fat, which puts your body in an unhealthy condition. A 1/2- to 1-pound weight gain per week means you'll add muscle as you put on weight, if you're lifting weights as part of your overall plan. It takes just an extra 250 to 500 calories per day to achieve this rate of gain.
Ask a dietitian or doctor to help you determine how many calories you need to support your current weight, then add 250 to 500 calories to that number to estimate the total number of calories you should eat each day. One high-calorie snack daily in addition to what you already eat, or incremental increases of calories throughout the day, can help you gain weight. As your body changes, be realistic in your expectations, even if that's lean and lanky and not linebacker thick.
Make Meals More Calorie Dense
To ensure you're eating enough to support your weight and put on pounds, make calorie-dense choices at meals. Opt for thicker slabs of whole-wheat or pumpernickel bread instead of flat bread, pita or white varieties. Order, or make, homemade chili or bean soups instead of choosing broth-based chicken noodle. Serve yourself extra sweet potatoes, corn and peas at dinner rather than eating only low-calorie, green salads.
Higher-calorie fare doesn't have to mean eating processed pizza, burgers and fries. Instead, increase the calories of the healthy foods you eat by adding more quality calories. For example, toss whole-wheat pasta with a tablespoon of olive oil before saucing for an extra 120 calories; add 1/4 of a sliced avocado to a turkey sandwich on whole-wheat bread to add 81 calories; or cook oatmeal in a cup of whole milk instead of water for another 150 calories.
Snack Often on Calorie-Dense Foods
Feeling stuffed all the time can make you not want to eat and thus undermine your goal to gain weight. Snacking regularly, however, is necessary; you don't want to go more than a few hours without taking in calories. Snack between meals and before bed to ensure you're getting all the calories you need. Choose calorie-dense foods such as nuts, trail mix, dried fruit, seeds, granola and pretzels with nut butter so you can enjoy moderate servings that won't overly fill you up.
For example, 1/2 cup of mixed, roasted nuts contains about 440 calories; 1/2 cup of raisins contains 215 calories and 1/2 cup of granola cereal contains 210 calories. Any combination of these snacks helps support weight gain, and you can conveniently pack them for snacks on the go.
If You're Skinny, Strength Train to Gain Weight
Burning too many calories daily can interfere with your calorie surplus, but being sedentary won't help you feel or look more healthy. Weight training, especially with heavy weights for one to three sets of four to eight repetitions, helps your muscles grow and as a result, you gain weight. Address all the major muscle groups at each of two to four workouts per week.
Fuel before and after your gym session to replace lost calories and add a little additional protein, which supports muscle growth and repair. A smoothie made with whey protein, fruit, nut butter and milk, a meat and cheese sandwich, or eggs with whole-grain toast are healthy workout snack options.
Short bouts of moderate-intensity cardiovascular activity, such as brisk walking or cycling, rev your appetite and support heart health. Aim for 20 to 30 minutes on most days.