Despite numerous claims that meal-replacement products provide sufficient nutrition and calories, using them over a long period, instead of eating three regular meals a day, could pose health risks, according to experts.

Zhu Yi, assistant professor at the China Agricultural University College of Food Science and Nutritional Engineering, said most meal replacements on the market use dietary fiber as their main ingredient, which satisfies the appetite but it is difficult to digest. However, they lack other types of nutrients.

"At present, there is a nutrition problem with many meal substitutes on the market, so there is a certain health risk in using them instead of three meals a day," he said.

Zhu said the healthiest way to lose weight or strengthen and build the muscles is a change of lifestyle, such as eating home-cooked meals with fresh ingredients as often as possible and taking regular exercise.

He added that sometimes meal-replacement products can be convenient in today's fast-paced working environment, but they cannot be long-term substitutes for regular food.

"There are many reasons for obesity," he added. "Meal-replacement products might be helpful for gluttons who want to lose weight, but may not necessarily be effective for others who have such issues."

Yang Yuxiang, a senior nutritionist and psychologist in Beijing, said choosing healthy meal-replacement products could be an acceptable substitute for people who want to control their weight, as long as they use them only occasionally.

"Meal replacements need to have enough healthy nutrients as well as vitamins and minerals," she said.

Yang said many brands tend to exaggerate by claiming that their products can completely replace regular meals or achieve weight loss.

Wu Juntong, a 22-year-old student from Renmin University of China, said she tried a type of oatmeal biscuit promoted as a meal replacement, but found that it did not live up to its billing.

"It claimed to satisfy the appetite, but this feeling did not last long, and it could barely replace a meal," she said.