Previewing his strategy, Prof Trenell said one key was to undertake short bursts of intense exercise most days.
"Central to this is the seven-minute high-intensity interval training programme - known as HIIT - which involves alternating bursts of high-intensity effort with periods of recovery.
"The long-term benefits from interval training are similar or, in some cases, even better than regular, longer-duration, moderate-intensity aerobic exercise."
Examples of "burst" activities - which are undertaken for around 30 seconds at a time - include push-ups, squats, star jumps, step-ups or even something simple such as running on the spot.
Seven bursts are interspersed with short rest periods, which start at 50 seconds but are then reduced to 30 seconds as the weeks pass.
The regime is preceded by 90 seconds of warm-ups and two minutes of stretching, to reduce muscle soreness and the risk of injury.
But Prof Trenell, who recently featured in the BBC series How To Stay Young, warned his regime was by no means all about exercise.
"If you want to lose weight it's about exercising more - and eating less," he said. "What people tend to do to lose weight is either just exercise more or diet. Neither approach works well."
Those who exercised a lot tended to increase their food intake too, he said, while "if you just diet, you are not improving your fitness at all".
He recommends ditching cakes, pastries, biscuits and processed meats - which are all high in unhealthy saturated fats - as well as high-sugar breakfast cereals and white bread because these cause blood sugar levels to spike.
Switching to "slow energy release" wholegrain foods, nuts and olive oil, as well as limiting carbohydrates, would help cut cravings and overall calorie intake, Prof Trenell said.
"Depending on your starting weight and how hard you work, you can lose up to a stone," he added.
"Remember to consult your GP before embarking on any new diet and exercise regime."