Italian scientists have conducted research which shows taking vitamin D can help obese and overweight people lose weight.

Taking vitamin D supplements has been found to aid weight loss in obese and overweight people, Italian researchers have found.

Scientists at the University of Milan estimate that in northern Italy, severe vitamin D deficiency ranges from six per cent in overweight people to 30 to 40 per cent in the morbidly obese.

Almost all obese subjects did not have a vitamin D level in the optimal range.

For the study they recruited 400 obese or overweight adults who were split into three groups - those who took no supplements, those who took 25,000 vitamin D units a month, and those who took 100,000.

All participants were put on the same balanced, low-calorie diet.

After six months, only those who took 100,000 units a month achieved optimal vitamin D status.

However, a significantly greater weight decrease and reduction in waist circumference was observed in both groups that took the supplements.

Those who took 25,000 units lost an average of 3.8 kilograms, while the figure was 5.4kg for the 100,000 unit group and 1.2kg amongst those who took no supplements.

"The present data indicate that in obese and overweight people with vitamin D deficiency, vitamin D supplementation aids weight loss and enhances the beneficial effects of a reduced-calorie diet," the study's authors said.

"All people affected by obesity should have their levels of vitamin D tested to see if they are deficient, and if so, begin taking supplements."

Another study being presented at this week's European Congress on Obesity in Prague, Czech Republic, found that living at higher altitude was associated with a lower risk of becoming overweight or obese.

The research, led by the University of Navarra in Pamplona, Spain, analysed more than 9,000 Spanish graduates and discovered that participants living at 456 metres or higher had 13 per cent less risk of becoming overweight or obese than those living at 124 metres or below.

They said this was likely to be due to hypoxia conditions, meaning lower concentrations of oxygen in the air, which suppresses hunger due to increasing secretion of leptin.