You might hear more about the struggle of losing weight -- but if you're naturally thin, gaining weight can pose just as much of a challenge. The Centers for Disease Control and Prevention estimates that close to 2 percent of American adults qualify as underweight, meaning their body mass index, or BMI, is below 18.5. When it isn’t simply a genetic trait, being underweight is often accompanied by malnutrition and increased health risks.
Daily Calorie Increase
Understanding calorie basics -- how many calories your body needs to maintain itself, and how many additional calories you may need to consume to gain weight -- is fundamental to any weight-gain effort. Because it takes about 3,500 additional calories for the average person to gain a pound of weight, eating an extra 250 calories every day should, in theory, cause you to gain about half a pound a week, just as adding 500 calories to your daily diet should, theoretically, cause you to gain about 1 pound per week.
When you’re underweight, particularly if you have a high metabolism or you’re naturally lean, your body may require more than the standard 3,500 extra calories to gain a pound of weight. Keeping track of your progress allows you to see whether the number of calories you’re eating is getting you to your goal at the desired rate; you may need to steadily increase your intake to improve your progress.
Healthy Dietary Strategies
Just as eating more calories is a must for weight gain, eating the right kind of calories is a must when it comes to maintaining -- or improving -- your health as you gain.
You probably already know that you can gain weight by starting a soda habit or consuming more pizza or muffins, but increasing your intake of sugary beverages and processed foods may eventually help you pack on belly fat, the kind that can increase your risk of heart disease and diabetes.
Instead, aim for a balanced diet based on whole foods, including plenty of vegetables, fruit, whole grains, lean proteins and healthy fats, and make your additional calorie more of the same. Snack on dried fruit, a handful of nuts or a thick piece of whole-grain toast smeared with peanut butter, avocado or hummus. Add chia seeds, wheat germ or ground flaxseed to your everyday yogurt, oatmeal or smoothie. Put an extra slice of cheese on your sandwich, add grated cheese to to a salad, or stir a dollop of whole-milk yogurt into a bowl of soup.
How you eat your calories can be as important to your success as the kind of calories you eat, particularly if you have a small appetite. To get more calories without feeling stuffed, try eating three larger-than-usual meals a day, along with two energy-dense snacks.
Strength Training Benefits
For the average person, no weight-gain program is complete without some form of resistance training. This form of exercise, also known as strength training, helps your body build lean tissue, including muscle and bone. Turning extra calories into lean tissue will increase your overall strength, enhance your appearance and protect you from gaining too much fat.
Although you can’t necessarily change your body type – some people build muscle more readily than others – everyone can increase lean tissue to some degree. Multi-joint, compound movements, such as squats, lunges and pull-ups, are examples of strength training exercises. In addition to incorporating a balanced selection of exercises, a basic, physician-approved resistance program should take several variables into account, including intensity, number of repetitions and sets, tempo and rest intervals.
Concerns and Limitations
Before embarking on any weight-gain plan, it’s important to see a qualified physician to discuss your overall health. Although genetics, high metabolism, high physical activity or malnutrition can cause someone to be underweight, as can certain underlying health issues, including thyroid disorders, digestive diseases, diabetes, cancer and psychological issues such as depression. Your doctor may be able to offer you a clean bill of health, sound, specific advice and the go-ahead to put your plan into action. Otherwise, if you do have an underlying health issue that’s caused you to lose weight or is preventing you from gaining weight, your doctor can help you address those more pressing concerns first.
If you’re genetically thin, it’s important to keep in mind that you may not be able to change your body as much as you’d like. Although everyone can affect their physique, you might be limited in how much change you can affect -- it’s not always possible to turn a lithe runner’s body into that of a linebacker’s.