Gaining just five pounds in weight can raise a healthy adult's blood pressure, a new study has found.

While many people are aware of the dangers of gaining a lot of weight, US scientists wanted to investigate any potential dangers associated with gaining a small amount - between five and 11lbs.

Sixteen people of normal weight were assessed over an eight week period. All were aged between 18 and 48.

At the start of the study period, their blood pressure was measured using a 24-hour monitor. The participants were then fed 400-1,200 extra calories per day, with the aim of increasing their body weight by about 5%.

Their blood pressure was assessed again at the end of the eight-week period and they were then compared to 10 people of normal weight who had not gained any extra weight over the study period.

The study found that those who gained between five and 11lbs did not record a change in their insulin, blood sugar or cholesterol levels. However their blood pressure did increase. Furthermore, those who gained more weight in their abdomen area recorded a bigger increase in their blood pressure.

"To our knowledge, for the first time, we showed that the blood pressure increase was specifically related to increases in abdominal visceral fat, which is the fat inside the abdomen. Our research suggests that healthy people who are more likely to gain weight in the stomach area are also more likely to have their blood pressure increased," commented the study's lead author, Dr Naima Covassin, of the Mayo Clinic in Rochester, Minnesota.

She emphasised that while there is a lot of awareness of the health effects of obesity, ‘it seems most people are not aware of the risks of a few extra pounds'.

"This is an important finding because a five to seven-pound weight gain may be normal for many during the holiday season, the first year of college or even while on vacation," Dr Covassin added.

Details of these findings were presented at the recent American Heart Association's High Blood Pressure Research Scientific Sessions 2014 in California.