Exercise is a vital part of living a healthy life - helping to boost fitness, ward off disease and keep your waistline in check.

A study by scientists at the London School of Economics, this week, claimed a brisk 30-minute walk each day is a more effective way to lose weight than running or going to the gym. But, how much exercise do personal trainers, whose jobs depend on their getting results, say we need to do to shed pounds? 

Dr Grace Lordan, a specialist in health economics led the research at LSE.

Her team compared the measurements of people who performed half-an-hour of fast-paced walking compared to those who did the same amount of heavy housework, manual labour and sports, including rugby. The waistline and BMI measurements showed that men and women who regularly walked briskly for more than 30 minutes had lower BMIs and smaller waists than those who engaged in regular exercise. 

These findings were based on physical activity levels from the annual Health Survey for England between 1999 and 2012.

So what do personal trainers - who get paid to help people lose weight through exercise - think? We asked fove of Britain’s best just how much exercise do we actually need to do to lose weight.

‘To lose weight you need to think of it on a weekly scale rather than a daily scale,’ Justin told Healthista. ‘To truly optimise fat loss, it’s three hours work a week. ‘This does not just mean three hours in the gym it means three hours of actual work time.’ He said ‘people can spend an hour and a half in the gym but actually only be doing 40 minutes work’.’ He has seen numerous case studies lose weight and said: ‘You need to make your ratio of active to rest time in the gym 2:1.  ‘This would mean if you are spending forty seconds working you should only be spending 20 seconds resting.’