This article originally appeared on Greatist.com
There are lots of theories about why naturally thin people have the bodies they do, from genetics to stronger satiety cues (some people can feel fuller faster, prompting them to eat less). Regardless, it's important to note that if someone is underweight, it's not proof-positive that they have an eating disorder.
According to the Body Mass Index (BMI) scale (which uses a person's weight and height to estimate their level of body fat), having a BMI of less than 18.5 qualifies as being underweight. Interestingly, of all the BMI calculators we sampled, every one of them included information on how to lose weight. None of them recognized that some people might in fact be looking to gain weight.
Perhaps this is because underweight people are an increasing minority. The number of Americans who are underweight is the lowest it's been since 1988: Approximately two percent of adult women and one percent of adult men fell into the category of "underweight" between 2007 and 2010. Whatever the reason for thinness, people sometimes invalidate the health concerns of those who need to gain weight.
More: Gaining Healthy Weight
There's a stereotype that nobody can be naturally underweight, says Greatist Expert and trainer Jen Cassetty, so, naturally thin people often face some kind of discrimination. Yet underweight people (particularly men) are just as much at risk for health concerns as overweight and obese people. Being significantly underweight is associated with negative health effects that include lack of energy, nutritional deficiencies, a weakened immune system, osteoporosis, and, in women, loss of menstrual function and complications with pregnancy.
As with any diet or exercise plan, it's important to consult a physician or nutritionist before adopting any weight-gain diet. A doctor can also help rule out other health issues that might be contributing to being underweight, such as thyroid problems, parasites, or disordered eating.
1. Keep a Food Diary
Chart what and when you eat every day for several weeks to learn about your eating habits and identify places to add calories. Online programs like MyFitnessPal and Fitday can make tracking easy. (They're also good tools for keeping track of your actual weight.)
2. Add it Up
Try adding an extra 200+ calories a day in the beginning, Cassetty says, and adjust up or down depending on results.
3. Focus on Quality, Not Quantity
Even when you're trying to gain weight, eating burgers, chips, and milkshakes all day, every day isn't great for a body. Instead, choose nutrient-dense foods from all food groups, Cassetty says. Good options include whole grains like whole wheat pasta, fruits and vegetables, nuts, and lean protein.
More from Greatist: Is Whole-Wheat Pasta Healthier?
4. Eat More Frequently
And never skip meals! It's easy to feel full fast when you start introducing more calories into each meal; changes in food intake might also bring on gastrointestinal issues and even acne. Make things easier on your belly by spreading calorie intake out over five to six smaller meals throughout the day.