Why So Thin?
There are many reasons why people may find it hard to gain weight. Genetics can obviously play a role, but individual personalities and the environment can be strong factors.
"Sometimes people think they just have a fast metabolism, but that's not always the case," says Cindy Moore, MS, RD, director of nutrition therapy at the Cleveland Clinic Foundation, and a spokeswoman for the American Dietetic Association (ADA). "They just might be more physically active."
For example, there are people who tend to move around more, burning more calories than they take in. They're either always the first ones to volunteer to pick up after a spill, to do the chores, to walk everywhere, or to play a lot of sports. This level of physical activity is not a bad thing, says Moore, but being aware of it is important in understanding the factors affecting one's weight.
Then there are others who lose their appetite, experience a change in metabolism, and/or lose poundage and muscle mass fast because of various reasons, including illness, chronic pain, depression , stress , and side effects from drugs.
In children, the inability to gain weight may signal a condition known as "failure to thrive," which means a kid is not growing appropriately for his/her age. This may be caused by an illness, or eating patterns dictated by a parental idiosyncrasy. According to Wahida Karmally, DrPH, RD, spokesperson for the ADA, there have been kids who have not developed properly because they did not receive enough nutrients from being on a raw food, macrobiotic, or vegan diet .