We'd all like to magically lose weight simply by taking a pill. Here's something almost as good: Weight gain slows dramatically among children who took a prebiotic, a University of Calgary study found.

Prebiotics are carbohydrates that cannot be digested by the human body. They help to stimulate the growth of beneficial bacteria that are already present in the digestive tract. They may also alter the microbial population living in the gut and reduce body fat in overweight and obese children.

Non-invasive and inexpensive, prebiotics may turn out to be a plausible treatment for overweight and obesity in children.

Researchers studied the effect of a prebiotic fiber given to 42 overweight or obese children between the ages of seven and 12. Some of the children were given the prebiotic fiber mixed with water once a day for 16 weeks, while others were given a placebo.

After four months, the children who drank the water containing prebiotics had less body fat than the children given the placebo, and the University of Calgary researchers projected that their annual weight gain would be about 6.6 pounds — what would be expected in a growing child. Among the children who drank the placebo with no prebiotics, the projected increase in weight was 17.6 pounds. The prebiotic also prompted shifts in the bacterial population in the gut that did not occur in the children drinking the placebo.

“Powdered fiber, mixed in a water bottle, taken once a day is all we asked the children to change, and we got, what we consider, some pretty exciting results — it has been fantastic,” said lead author of the study, researcher Raylene A. Reimer, in a statement.

Obese children are at greater risk for developing chronic adult conditions such as type 2 diabetes, bone and joint problems, and risk factors for heart disease like high blood pressure and high cholesterol.

The social and emotional impacts of obesity on children are worrisome, as well. Obese children are often bullied and teased, and have a greater chance of suffering from low self-esteem, depression and negative body image.

Obese children are more likely to become obese adults and run a greater risk of developing heart disease, type 2 diabetes, metabolic syndrome and several forms of cancer.

The results lay a foundation for studying the effect of prebiotics on a larger population of children. Non-invasive and inexpensive, prebiotics may turn out to be a plausible treatment for overweight and obesity in children.

The study is published in Gastroenterology.