Bellies wobbling and chubby limbs swinging, dozens of sweaty traffic cops exercise to the rhythm of Thai pop songs as part of a scheme to reduce the number of overweight police in Bangkok.
Poor diets and long hours in a sedentary job on the city's gridlocked streets have left the Thai capital's traffic police prone to piling on the pounds.
But their health -- and the public image presented by potbellied officers -- has become such a worry that police bosses have laid on free fat-busting classes, enlisting nearly 60 volunteers for a two-month 'Fit and Firm' programme.
After barely a fortnight on the course, Senior Sergeant-Major Nitas Saisaard says he now weighs a still hefty 138 kilogrammes (304 pounds) but has shed six kilos and reduced his waistline by three inches.
"When I work, it is definitely difficult... when I am directing the traffic -- in the centre of roads, between cars -- I sometimes get hit, brushed by wing mirrors," the 48-year-old says, sweat rolling down his forehead after a class.
But twice-weekly sessions -- including yoga and aerobics -- are so far working for Nitas, along with a new diet of fruit and soups that banishes his favourite fried street food and bowls of white rice.
"I gained weight because I eat a lot at late night... we (traffic police) have uncertain schedules," says Nitas, who has joined similar schemes before but never quite managed to win his personal battle against the bulge.
Bangkok's Metropolitan Police Bureau wants cops with waistbands over 36 inches to consider doing the course, enticing them to lose over 10 kilos with prizes of nearly $160 for the best performers.
"Senior policemen saw that our officers are too chubby... too fat, so they decided they should lose weight", said Lieutenant Colonel Sujit Suksamai, who is also taking part in the course.
"When police are too fat, they can't work quickly. Reducing the fat makes them stronger, healthier and faster."
Police chiefs have frequently tried to encourage their colleagues to tackle their expanding paunches by running regular fitness classes including a 'Fat Fighters' course earlier this year.
Slimming down is also an issue of public confidence in the police, says health expert Kawita Kruenjit who leads some of the exercise and health sessions at a Bangkok private hospital.
"When the general public see fat police they wonder 'how are they going to run after the bad guys?'" she added.
In their defence, police say the stress of 15-hour shifts guiding traffic in one of the world's most congested cities, where they receive little love from motorists who routinely stew in hour-long traffic jams, makes the job incompatible with a healthy lifestyle.
But it is the traffic police's proclivity for the cheap, fatty treats dished out by Bangkok's ubiquitous street stalls that are doing the most damage, according to Doungrut Wattanakitkraileart, who researches the health of police officers at Bangkok's Mahidol University.
More than half of 265 traffic police she surveyed in 2011 in one Bangkok district suffered high cholesterol.
"Food on sale near police stations is unhealthy, it is oily and salty -- coconut milk curries and fattening dishes... officers can just walk to the front of their police stations and buy their food", she said, adding low wages deter many from a healthier diet.
Fit and Firm is changing habits and some attitudes, even among those who are only marginally on the wrong side of scales.
"The first time after 45 minutes of aerobic dance non-stop, my whole body was stiff. But now... I can do it non-stop," senior sergeant major Wichien Noppan, who is just over 90 kilos, said proudly.
"We have to appear in public, so looking smart comes first and our look and shape should be firm," he added.
But for others the prospect of slimming down remains distant as long as Bangkok's street food stalls continue to tempt with delicious, if calorie-heavy, meals.
Scoffing a lunch of white rice and a Thai curry in a traffic booth at a busy intersection in central Bangkok, Sub Lieutenant Banyong Wannawong admits it is hard to change the eating habits of a lifetime.
Weighing in at a scale-tipping 130 kilos that means his uniform sticks tightly to his paunch, Banyong pithily explains why he is unlikely to trim down anytime soon.
"My favourite foods are fattening... I could eat them less but I won't enjoy them as much."