Government guidelines on how much weekly exercise people should do are flawed, according to a senior Canterbury Christ Church University scientist.
Professor Mike Weed argues that recommended levels for physical activity designed to combat soaring obesity rates in the UK are off-putting to people who cannot achieve them.
The government says that adults should do two-and-a-half hours of moderate activity or 75 minutes of vigorous activity each week.
But Professor Weed, director of Christ Church’s Centre for Sport, Physical Education and Activity, said: "These guidelines could be doing more harm than good.
"Only 10 to 15% of adults achieve the recommended 150 minutes.
"This suggests that a guideline of 150 minutes is unachievable and there is the possibility that it may be off-putting to the least active.
"The government does not currently measure the effectiveness of these guidelines, so there is no indication as to whether they are working or not.
"It may be the case that if the guidelines were set at, for example, 60 minutes, then perhaps this would be seen as a more achievable target by the least active and we might actually succeed in shifting the curve of physical inactivity."
It is calculated that 64% of adults in the UK are overweight or obese, putting a strain on NHS services.