SINGAPORE – Madam Woon Mee Yin, 64, makes herself go to the gym at least three times a week because she is afraid of regaining the 15kg she put on in her late 50s.

The 1.55m-tall pre-school teacher had been 49kg to 51kg for most of her adult life. But at age 57, she weighed 67.5kg. This was the result of her indulging in sugary foods and desserts along with her then pregnant daughter.

Madam Woon realised she had to address her weight gain when she could no longer squat to pick up things that she had dropped.

In 2017, she signed up for personal training at a gym. She now trains three to four times a week, and will take a long walk of 13,000 steps before at least one gym session. She currently weighs a healthier 52.7kg.

“Sometimes, my laziness will come back and I don’t want to go to the gym,” she says. “But when I think that I might gain weight, I force myself to go.”

She associates her habit of increased exercise with her weight loss. But does exercise really help to shed the kilos?

Mongolia-born bodybuilder Tuvshintugs Javkhlantuul, 36, gained 30kg during each of her two pregnancies, but the Singapore permanent resident lost this weight within two years of the birth of each son just through taking gentle walks with her family.

“I figure it’s genetic,” says Ms Jaka, as she is known to her clients. Her mother also gained more than 20kg when pregnant, and lost the weight relatively easily. Ms Jaka, a senior personal trainer at fitness brand TFX, is 1.59m tall and weighs 52kg.

Competitive bodybuilder Tuvshintugs Javkhlantuul gained 30kg during each of her 
two pregnancies, but lost the weight within two years of the birth of each son just 
through taking gentle walks. ST PHOTO: LUTHER LAU

Some research shows that exercising to lose weight might sometimes backfire. A paper published in the journal Obesity in 2016 tracked 14 of the 16 contestants on the 2009 season of American reality TV show The Biggest Loser (2004 to 2020). Participants in that show lost large amounts of weight through dietary changes and gruelling exercise, but regained much of that weight six years later.

Five were almost back at their original weight and nearly all had much slower metabolic rates than expected, which means they burnt fewer calories at rest.

What does that mean for those looking to lose weight?

Exercise and calorie burn for weight loss

Weight loss is a matter of increasing calorie burn, or energy expenditure, so that the body burns off excess weight stored as fat or other tissue.

Dr Victor Tan Aik Khien, a consultant at Changi General Hospital’s Department of Sport and Exercise Medicine, says net energy expenditure can be increased by limiting caloric intake through healthy dieting, or increasing energy expenditure through exercise, or both.

However, increasing exercise does not always lead to increased caloric burn in the long term.

Dr Grace Huang, general physician at DTAP Clinic @ Robertson, says there is a theory of “constrained energy expenditure”. It suggests that the body adapts to high levels of physical activity by reducing energy spent on other physiological processes.

“This means that beyond a certain point, increasing physical activity does not lead to a proportional increase in calories burned. The body aims to stay within a fixed energy budget, leading to a plateau in total daily energy expenditure,” she says.

Ms Irene Chu Jia Huey, principal physiotherapist at Singapore General Hospital’s (SGH) Department of Physiotherapy, says weight regulation involves the complex interplay of many factors – genetic, developmental, hormonal, behavioural and environmental.

Many of these factors are not yet fully understood. “What we do know is that these factors are highly interactive. When we manipulate one component, other components may change or compensate,” she says.

She adds: “Our bodies will always have a strong and persistent biological drive to regain lost weight, through ways such as increasing appetite, reducing our desire to be physically active, and changing the energy demands of other physiological processes.”

How much exercise will help with weight loss?

Dr Huang says when aiming to lose weight, exercise is less about burning calories than about building muscle. “Having more muscle mass increases the amount of calories your body consumes on a daily basis,” she says.

In addition, exercise can improve insulin sensitivity, which helps with blood sugar control.

Dr Huang adds: “One should not get obsessed with using exercise as a means to burn calories, but rather, to view it as a tool to build a better body composition in the long run.”

Dr Tan says to lose weight, overweight and obese patients are recommended to do at least 250 minutes of moderate to vigorous intensity exercise a week.

These are guidelines set by the American College of Sports Medicine. In comparison, the Singapore Physical Activity Guidelines released in 2022 recommend that, in general, adults aged 18 to 64 engage in 150 minutes of such exercise a week.

Dr Tan says when performed correctly, those 250 minutes of exercise are the equivalent of reducing 2,000 calories a week. Exercises might be aerobic, such as brisk walking, cycling and swimming; or resistance training, often involving lifting weights; or moves to improve flexibility.

He says overweight or obese individuals are usually encouraged to do large volumes of moderate intensity aerobic exercise to start with. “Aerobic exercise refers to any exercise that uses the large muscle groups, can be maintained continuously and is rhythmic in nature. Aerobic exercise can help one to lose calories through increased caloric expenditure and to lose fat mass over time.”

Resistance exercise helps increase muscle mass, strength, endurance and power, as well as improve muscular control and coordination. “Having stronger and larger muscle groups over time improves an individual’s aerobic fitness as the individual is able to tolerate more vigorous aerobic exercise for a longer duration, thereby increasing the likelihood of caloric loss,” says Dr Tan.

Lifestyle modifications with dieting and exercise can lead to a person losing 5 to 10 per cent of his or her weight over six months, he adds.

As people begin to lose weight, their bodies will adjust and slow down metabolism in order to not expend too much energy. This is why a person might see his or her weight plateau after a period of weight loss or even experience weight gain, says Dr Tan.

“When individuals successfully adapt to exercise and adopt exercise regularly as part of their lifestyles, they can opt to increase the intensity of exercise to expend even more energy to lose more weight,” he adds.

In Madam Woon’s case, she has gone from moderate cardio training to doing high-intensity exercise with battle ropes and weighted balls.

Her trainer, Mr Leonard Rosco, 40, says: “We have to change workouts regularly because the body adjusts.”

The fitness team leader at exercise chain True Fitness adds that alongside exercise, sleep and diet play important roles in weight loss.

Madam Woon Mee Yin has gone from moderate cardio training to doing high-intensity 
exercise with battle ropes and weighted balls. ST PHOTO: SHINTARO TAY

Exercise versus weight-loss drugs and surgery

Dr Tan says exercise allows for more restful sleep, which can also help with weight loss.

There is also the feel-good factor of increasing endorphins. This makes people feel more relaxed and confident about their weight-loss journey, he adds.

Dr Melvin Look, director of private practice PanAsia Surgery, says: “As we age, exercise takes on a far more important role than burning calories alone. Using our muscles helps to preserve functionality of our musculoskeletal system, strengthens our bones, keeps our joints agile and improves our core strength and balance. This helps prevent injuries and falls as we age, and is a key objective in any healthy longevity programme.”

The consultant surgeon in gastrointestinal, laparoscopic and obesity surgery emphasises that diet, exercise and lifestyle changes are essential to any weight-loss programme. However, he adds, significant weight loss might require the use of weight-loss drugs, or procedures to reshape the stomach or reduce its capacity.

According to Dr Tan, weight-loss medications such as semaglutides can result in up to 15 per cent weight loss, while bariatric surgery can help morbidly obese patients lose up to 35 per cent of their weight.

However, he and other professionals caution that weight-loss medications are not meant to be taken in the long term. People taking such drugs might regain weight after stopping if they do not make lifestyle changes.

Up to 76 per cent of those opting for surgery might also see weight regain because of a sedentary lifestyle or maladaptive dietary behaviours, such as binge eating.

Lifestyle changes thus remain important to sustained weight loss and weight maintenance, he adds.

Ms Chu of SGH says: “In the long run, exercise is a highly economical and cost-effective way for weight and health management, especially for those who have difficulties affording long-term medications and care.”

She adds: “Exercise can be empowering to individuals as it gives them a sense of control over what they can do to maintain a healthy weight.”

For personal trainer Jaka, exercise and bodybuilding are ways to find an identity outside of being a mum and wife.

Ms Jaka performing a Step Climber exercise. ST PHOTO: LUTHER LAU

Apart from training clients, she does between 120 and 150 minutes of exercise daily, including 60 minutes of cardio.

She eats four times a day and her meals are homemade and packed by her Singaporean husband, who works from home and is in the finance sector.

“Exercise gives me a sense of purpose,” she says, adding that days without activity are difficult to get through. “Fitness is saving my life.”

The Bottom Line: Exercise is important to long-term health as well as weight management. Overweight or obese individuals can aim for 250 minutes of exercise a week, done at least at a moderate intensity.