Gaining weight healthily is as hard as losing it and there’s no simple remedy for those who are underweight. Provided to China Daily

Underweight people have just as much trouble putting on the pounds as obese people have losing them, and they have also related health risks. Sandra Trauner reports.

"I'd like to have your problem!"is a common remark made to underweight people, who tend to arouse more envy than sympathy. As doctors and nutrition experts well know, however, gaining weight healthily is just as hard as losing it, and may be even harder because the causes of being underweight are more complex and a remedy is not as simple.

"It wouldn't help to tell them to do the reverse of what people trying to lose weight are told to do," notes Kerstin Bernhardt, a dietary adviser who specializes in malnutrition.

Eating lots of fatty foods and sweets, and double portions of everything, "would not only be very unhealthy but also pointless or even harmful," she says.

The problem of the underweight, after all, is that they are unwilling or unable to eat enough, or they eat like a horse but still do not gain weight.

They have a fast metabolism and can eat whatever they want without putting on kilograms. "It's mainly a genetic predisposition that can't be controlled," remarks Susanne Nowitzki-Grimm, a German dietary adviser who co-wrote the book on the subject.

People with a slow metabolism deposit most of the energy they take in with food as body fat. People with a fast metabolism burn this energy off, producing heat.

To someone who is overweight, a fast metabolism may seem desirable. But from a medical standpoint it is a problem.

"Being underweight is usually accompanied by a deficiency of essential nutrients and/or trace elements," note the authors of the website German Dietary Advice and Information Network. This increases the risk of developing disorders such as osteoporosis, impairs muscle function, increases susceptibility to illness and slows the healing of wounds.

The World Health Organization defines being underweight as having a body mass index (BMI) under 18.5. Someone who is 1.6 meters tall and weighs about 60 kg has a BMI of 23.4. An ideal BMI is between 20 and 25.

Underweight people are often elderly, have little appetite or perhaps are no longer able to chew properly. People can also lose a lot of weight due to a serious illness or chemotherapy.

An underlying health problem is sometimes to blame, for example a metabolic disorder. But young, healthy people can be affected, too, such as when emotional stress leads to serious weight loss.

"There are people who eat more when they're depressed, and people who don't eat any more," Bernhardt says.

A classic case is lovesickness. Your stomach feels as though tied up in knots, your nerves are shaky, and after two bites of food you are full. Before long, your body is running low on important nutrients, deficiency symptoms appear and you either become lethargic or more nervous - in any case you eat even less "and then enter a downward spiral," Bernhardt says.

What to do when your trousers get baggy, your bones start to stick out, your energy level drops and your irritability rises? Eat regularly and often, advises Germany's Federal Center for Health Education. It recommends lots of milk, cheese, yogurt and cream, oil-fortified foods, nuts and fruit juices.

You have to look around for a long time before you find a "weight-gain workshop" lasting several months, such as the one that Nowitzki-Grimm offers in her Swabian town. Applicants far outnumber the places available.

Nowitzki-Grimm basically tells participants the same thing you can hear at a weight-loss workshop: Eating habits must be changed. When things go well, the participants gain a kilogram a month, she says.