by Bonnie Bruce, DrPH, MPH, RD
Our nation is so focused on the current obesity epidemic, and there is so much emphasis on losing weight, that those of us who are too thin or struggling to gain weight seem at times to be largely forgotten. But being underweight is more common than is usually realized, with about 2% of all Americans fitting into this category.
There’s more than one reason for being thin or underweight. Sometimes, of course, people are thin at least in part because of their genes. If you are thin and can’t seem to gain weight, even when you are trying in earnest, take a look at other members of your family. Whether your parents are just about the right weight, overweight, or thin will play a part in what your own natural body type is. And although you can change your body to a certain degree through diet and exercise, you cannot change your underlying body type. If you were born to be thin, it is unlikely you will ever be big and muscular.
Other possible causes of being underweight include overly restrictive, fad, popular, or medical diets; medical problems that impair the body’s ability to absorb and use nutrients from food; medicines that affect the appetite; not being able to afford, easily obtain, or prepare food; and psychological stress or social circumstances (for example, depression or loneliness) that take away the appetite. In addition, as people age, the senses of taste and smell diminish, making the thought of eating less interesting. Even the changes in eyesight that happen with aging can affect eating. I have worked with older clients who wouldn’t go out to eat because they couldn’t read the menu or who would limit their food purchases because they couldn’t read the food label.
Being underweight can also be the aftermath of some chronic conditions, such as rheumatoid arthritis (RA), and the percentage of people with RA who are underweight may be higher than for the population as a whole. RA may cause the appetite to wane or the sight or smell of food to become unpleasant or nauseating. Tender finger joints may make it difficult or painful even to try to stir a pot of soup or to hold a knife or fork. The depression that sometimes accompanies RA may take away the appetite, and some of the drugs used to treat it may do the same. The end result is that the body is not getting enough fuel for its needs, leading to problems such as fatigue, loss of muscle strength, and reduced ability to fight off infections.
It may seem surprising, but gaining weight can be as challenging or daunting as losing weight. The good news is that lots of people who want to gain weight are able to do so safely, without sacrificing good nutrition. Before you embark on a plan to gain weight, however, you should first make sure that you don’t have any other underlying, undiagnosed medical problems that may affect or be affected by your efforts to gain weight. This is especially important if you have lost weight unintentionally.
To gain weight you have to eat more calories than your body burns up. But how many calories do you need? Don’t just guess. You can use an online calculator such as the one available through ChooseMyPlate.gov's SuperTracker to come up with a number. Or if you are seeing a dietitian or know one, ask if he or she could give you a general idea of your calorie needs. Otherwise, here’s a relatively simple and easy way to get a rough estimate of the calories you need to gain weight.
First, multiply your current weight by 10. The number you get won’t take into account individual differences, such as gender, age, and body composition, but it will give you a rough idea of how many calories your body needs to meet its basic everyday energy needs. Second, add about 30% to that number to account for what you burn up in routine physical activity. Again, the number you get won’t take into account individual differences, but it will give you a rough idea of how many calories you need to sustain your current weight. Lastly, take that second number and increase it by 500. If this new number is realistic for you and you eat that many calories every day, you can expect to gain about a pound a week. Gaining one or two pounds a week is healthy and means that you are gaining weight at a good rate. If this doesn’t sound like much, think about it as gaining 4–8 pounds a month. If 500 calories more a day seems like too much, start small — even by adding only 100 calories a day — and increase as you are able. An extra 100 calories a day over and above what you are now burning up is powerful. It will result in a 10-pound weight gain over the course of a year.
To add the extra calories, you can eat more at standard meal times, eat more frequently throughout the day, or simply eat higher-calorie foods. Most people will take up parts of all these strategies. Whatever strategy you adopt, it is important that your plan for eating fits your lifestyle, needs, and preferences.
Last Reviewed on January 10, 2013
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