London, Aug 7 (IANS): Weight loss occurs in older adults as a result of the increased production of an hormone that gives a feeling of fullness, revealed researchers in the preliminary evidence.

"With ageing there is frequently a loss of appetite, termed anorexia of ageing, which can result in under-nutrition," said Mary Hickson, Professor at Plymouth University in Britain.

The findings showed that after eating, elderly people produce a greater amount of peptide YY (PYY) -- the hormone that tells humans when they're full.

This hormone results in the person feeling less hungry.

Previous studies had suggested that weight loss in the over-80s, termed 'anorexia of ageing', could be due to the lower production of ghrelin -- "hunger hormone" -- resulting in older adults feeling less hungry.

However, in the new study, each of the participants, produced a greater amount of PYY than their younger counterparts, while their ghrelin levels showed no change, the researchers said in the journal Appetite.

For the study, the team included six healthy women over the age of 80. They ate a breakfast after several hours of fasting.

Their hormone levels were then compared to those of a number of healthy younger participants in age brackets 20-39; 40-59; and 60-79.

The team measured levels of PYY at regular time intervals for three hours in each participant alongside levels of ghrelin.