According to the study, 52 per cent of Britons over the age of 40 say they are obese, compared with 40 per cent of younger people, but most are reluctant to try to lose weight through exercise.
The survey for a Health Insurance company found, just one in ten over-50s meet the recommended target of moderate exercise, such as fast walking, for half an hour, five times a week and a third admit to doing none whatsoever, 'The Telegraph' reported.
As many as 37 per cent of over-50s who do not exercise said they were physically unable to get fitter, 31 per cent said they were not motivated to do so and 22 per cent described themselves as "too lazy".
Among the over-50s who do exercise regularly, more than half said walking was their main form of exercise while 13 per cent swim and 10 per cent choose to cycle.
The survey, which also included questions about participants' diet, found that a third of over-50s eat the recommended five proportions of fruit and vegetable a day, compared with just a fifth of under-50s.
Fourteen per cent of the older group said they regularly exceed the recommended 21 units of alcohol per week, compared with just eight per cent of younger people.
"Whilst the over 50s tend to get it right with healthy eating, what they appear to need is something to motivate them to exercise, " Roger Ramsden, chief executive of Saga Services, said.