Obese patients can greatly improve their health by shedding just 5 per cent of their body weight, a study has found.
The small change led to a marked reduction in diabetes and heart disease risk, and better functioning of liver, fat and muscle tissue, scientists found.
Losing more weight did not result in progressively greater overall health benefit.
US lead investigator Dr Samuel Klein, director of Washington University's Center for Human Nutrition, said: "Our findings demonstrate that you get the biggest bang for your buck with 5 per cent weight loss.
"The current guidelines for treating obesity recommend a five to 10 per cent weight loss, but losing 5 per cent of your body weight is much easier than losing 10 per cent. So it may make sense for patients to aim at the easier target."
For the study 40 obese individuals were randomly assigned different goals - either to stay the same or to lose five, 11 per cent or 16 per cent of their body weight.
Tests of whole body, organ and cellular responses were carried out to measure the effects of weight loss.
Participants typically lost 5 per cent of body weight after 3.5 months, 11 per cent at around seven months and 16 per cent at 10 months.
Among the 19 volunteers who lost 5 per cent of their weight, cells in the pancreas became better at secreting the vital hormone insulin.
At the same time, cells in the fat, liver, and skeletal muscle tissue grew more insulin-sensitive.
Losing 5 per cent of body weight was also associated with decreases in total body fat and much less fat in the liver, both of which are linked to heart disease.
Patients who lost more than 5 per cent of their weight experienced further improvements in pancreatic cell function and muscle tissue insulin sensitivity. But their liver and fat tissue showed no sign of becoming more sensitive to insulin.
"Continued weight loss is good, but not all organ systems respond the same way," said Dr Klein. "Muscle tissue responds much more to continued weight loss, but liver and adipose tissue have pretty much achieved their maximum benefit at 5 per cent weight loss."
The findings are published in the journal Cell Metabolism.
Tracy Parker, a dietician at the British Heart Foundation, said: "This study is a reminder of the benefits of gradually getting to a healthy weight. Setting realistic goals such as 5 per cent weight loss is a good way to maintain healthy weight loss."
