But now a leading diet and exercise expert has come up with a plan to help people lose 6kg in two months - by getting active for just 30 minutes a week.
Mike Trenell, professor of movement and metabolism at Newcastle University, said his thoroughly tested approach could produce similar — and, in some cases, superior - fitness results to more traditional exercise regimes, which emphasise the time spent being active.
"Using my two decades in the field, I have devised a plan to help people lose 6kg, sleep better, balance their blood sugar, boost heart health and even fight dementia," he said.
"And it's all achievable with a simple diet and fitness plan that focuses on a set of exercises that you can do at home in less than 30 minutes a week."
Trenell will spell out his plan in full in an English newspaper on Sunday. But, previewing his strategy, Trenell said one key was to undertake short bursts of intense exercise most days.
"Central to this is a seven-minute high-intensity interval training programme 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 Trenell, who recently featured in the BBC series 'How To Stay Young,' warned that 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, Trenell said.
"Depending on your starting weight and how hard you work, you can lose up to 6kg," he added.
"Remember to consult your doctor before embarking on any new diet and exercise regime." - Mail On Sunday