Is it true that "you don't have to exercise every day"? Concentrated 75-minute walks can reduce body fat.

"Exercising less than three times a week is pointless."

Anyone interested in health or dieting has probably heard this phrase at least once.

When leading a busy life with work, house chores, and childcare, the "three times a week" figure can become a surprisingly high hurdle. Monday involves overtime, Wednesday has plans, and by Friday, you're exhausted. Before you know it, another week has passed without exercising—many people have had this experience.

However, a study that challenges this conventional wisdom from a different angle is gaining attention.

In a randomized controlled trial conducted by a research team from the School of Public Health at the University of Hong Kong, participants who performed a total of 75 minutes of high-intensity interval training (HIIT) in one day were compared to those who spread it over three days. After 16 weeks, there was no significant difference in body fat reduction, waist circumference, or improvement in cardiorespiratory fitness.

This study suggests that what might be more important than "how many days you exercise" is "how much exercise you accumulate over a week."

However, this doesn't mean "walking for 75 minutes once a week will easily make you lose weight."

The actual exercise was quite different from a leisurely stroll. It involved structured high-intensity interval training, alternating between brisk walking that raises your heart rate significantly and recovery periods with reduced intensity.

A closer look at the study reveals great potential for busy modern individuals, while also highlighting nuances that might not be apparent from headlines alone.

315 participants divided into three groups for a 16-week comparison

The study involved 315 adults in Hong Kong, with an average age of about 48, and approximately 65% were women.

All participants were overweight and met the criteria for "central obesity," where fat accumulates in the abdominal area. The average BMI was 28.7, and the average waist circumference was 94.8 cm.

The research team randomly assigned 105 participants to each of the following three groups.

The first group performed the weekly high-intensity interval training in one session.

The second group spread the same amount of exercise over three sessions a week.

The third group did not follow an exercise program but received regular health education as a control group.

The training period for the exercise groups was 16 weeks. Importantly, both the once-a-week and three-times-a-week groups had the same total of 75 minutes of high-intensity exercise per week.

The main objective of the study was to investigate whether the effect on body fat changes depending on whether the 75 minutes are done in one session or spread over three.

"Not 75 minutes of continuous all-out walking"

This point is particularly prone to misunderstanding.

The "75 minutes" in this study does not mean walking continuously to the point of breathlessness for 75 minutes.

The basic format was a 25-minute interval training session, combining 4 minutes of high-intensity walking with 3 minutes of low-intensity recovery walking.

During the high-intensity intervals, participants aimed to reach 85-95% of their peak heart rate, based on their individually measured maximum exercise capacity. During the recovery intervals, the intensity was reduced to 50-70%.

The three-times-a-week group divided this 25-minute interval training over three days.

Meanwhile, the once-a-week group performed three sets of the 25-minute interval training on the same day, with 15-30 minute breaks between sets.

The experiment used treadmills under the supervision of certified trainers, with participants wearing heart rate sensors, and speed and incline adjusted individually.

Thus, the conditions were different from taking a 75-minute walk in the park on a day off.

News headlines may highlight "brisk walking" or "walking," making it seem easy, but in terms of exercise intensity, it is classified as HIIT, or high-intensity interval training.

Fat reduction even with once-a-week exercise

The results after 16 weeks were intriguing.

Compared to the control group, the once-a-week group had an average of 0.8 kg less body fat, and the three-times-a-week group had an average of 1.0 kg less.

In terms of relative change from the original body fat amount, the once-a-week group saw a 2.6% reduction, and the three-times-a-week group saw a 3.5% reduction. Meanwhile, the control group saw almost no change, with a 0.2% increase.

At first glance, the three-times-a-week group appears to have slightly larger numbers.

However, statistically, there was no clear difference between the once-a-week and three-times-a-week groups.

Both exercise groups showed improvements over the control group in body fat percentage and waist circumference, and cardiorespiratory fitness also improved, with no significant difference between the once-a-week and three-times-a-week groups in the basic analysis.

From these results, the research team suggests that if the total exercise time per week is the same, consolidating high-intensity interval training into one day could be a realistic option.

"Once-a-week is not superior"

It's important to note that the study does not conclude that "once-a-week exercise is superior to three-times-a-week."

The results merely confirm that "when 75 minutes are consolidated into one session, the effects are similar to when divided into three sessions."

The situation is slightly different for weight and BMI.

After 16 weeks, while both exercise groups showed improvement trends, statistically significant differences compared to the control group were only confirmed in the three-times-a-week group.

Additionally, sensitivity analyses with more detailed condition adjustments suggested that the three-times-a-week group might be superior in improving cardiorespiratory fitness.

Therefore, understanding "exercising once a week is exactly the same as three times a week" is not accurate.

What was strongly indicated, especially regarding body fat and waist circumference, is that consolidating exercise into one day could still yield significant effects.

Why "once-a-week" holds significant value

The value of the study's results lies not just in the numbers of how much fat was lost.

More importantly, it presents a new option for those who say, "I can't exercise three times a week because I don't have time."

When starting to exercise, many people try to create an ideal schedule.

"Gym on Monday, Wednesday, Friday"

"Jog for 30 minutes every morning"

"Strength train four times a week after work"

However, once that schedule is disrupted, many people give up, thinking, "It's impossible this week."

What this study shows is that, at least under certain conditions, even if you can't secure exercise time multiple times a week, exercising on a day when you can find time is a viable method.

If only Saturday is available, exercise on Saturday.

If weekdays are busy with work, consolidate exercise on Sunday.

For those who have thought, "There's no point if I can't keep the ideal frequency," this result significantly lowers the psychological barrier.

The study paper also refers to this exercise pattern as "Weekend Warrior."

"Good news for busy people" on social media

This study has also been shared on social media.

The official account of the School of Public Health at the University of Hong Kong introduced the study results, stating that consolidating interval walking into one session per week led to reductions in body fat and improvements in cardiorespiratory fitness in adults with central obesity.

On X, accounts run by doctors and those sharing health information have shared the study in the context of it being a "realistic option for busy people." On Facebook, the content that "75 minutes of exercise once a week showed similar body fat reduction as exercise divided into three sessions" has been spread across multiple health-related pages.

On Instagram, accounts related to the University of Hong Kong have used the term "Weekend Warrior," introducing it as an exercise strategy for those with limited time.

Judging by publicly available posts found through searches, the part that particularly garners attention is the "once-a-week" aspect.

The gap with the conventional image of "needing to exercise every day" is significant, making it naturally a strong news topic.

However, on social media, the study results are often simplified to expressions like "just walk once a week to lose belly fat."

Considering the actual study conditions, caution is needed with this understanding.

Many of the SNS posts confirmed were content introducing the study results themselves and should not be taken as representative of the overall evaluation or opinions of SNS users. It should be viewed as a trend of publicly available and searchable posts, rather than as the "overall public reaction" to the study.

The key point is "intensity" rather than "walking"

Some might interpret the news as "just do 75 minutes of walking once a week."

However, a detailed reading of the study reveals that the keyword is "high-intensity" rather than "walking."

The goal for the high-intensity intervals was 85-95% of peak heart rate.

Although there are individual differences, this intensity is quite breath-taking.

It is entirely different from typical walking during shopping or commuting.

Furthermore, participants underwent a maximum cardiopulmonary exercise test at the start of the study, and their exercise intensity was set based on the results. Heart rates were continuously monitored during training, and exercise was conducted under the guidance of certified trainers.

The first four weeks included a period for acclimatization, incorporating lower body strength training and stretching exercises like squats, lunges, and exercises using resistance bands.

Suddenly starting high-intensity exercise with the mindset of "I'll walk all-out for 75 minutes starting today" does not replicate the study method.

For those without exercise habits, those with chronic illnesses, or the elderly, it is crucial not to increase intensity abruptly.

The study is not about dramatic weight loss

If viewing this study as the "latest diet method," there is another number to consider calmly.

In 16 weeks, the once-a-week group's body fat decreased by an average of 0.8 kg compared to the control group.

It was not zero, and it was a statistically significant change.

However, it was not a dramatic result like "lose 10 kg in four months."

Rather, the study evaluated factors like fat mass, body fat percentage, waist circumference, and cardiorespiratory fitness more than weight itself.

This is an important perspective when considering health.

It's not uncommon for the numbers on the scale to not change significantly even after starting to exercise.

Nevertheless, if waist circumference decreases, fat mass decreases, and cardiorespiratory function improves, meaningful changes might be occurring inside the body.

The study also highlights the importance of not evaluating the value of exercise solely by "how many kilograms were lost."

Some differences diminished after 32 weeks

Another intriguing aspect is the results at the 32-week mark, four months after the study ended.

Researchers continued to track participants after the 16-week exercise program ended.

As a result, at the 32-week mark, both exercise groups had significantly lower waist circumferences compared to the control group.

However, there were no significant differences between groups in total body fat, body fat percentage, weight, or BMI.

In other words, the effects of exercising for 16 weeks were not automatically maintained thereafter.

After the exercise program ended, no training facilities or interventions were provided by the research side.

The reality that emerges is that in health-building, it is important not only to achieve results in the short term but also to consider how to maintain those habits.

If the once-a-week method holds value, it is not because it is a "magical exercise that requires fewer sessions," but because it might be easier to continue in the long term.

Is the "Weekend Warrior" concept suited to modern society?

Being busy with work on weekdays and exercising on weekends.

Previously, the style of "it's better to split exercise into smaller sessions" was often recommended, but in recent years, it has become a subject of research interest.

This study can be seen as taking that trend a step further.

Especially for those who cite "lack of time" as one of the main reasons for not exercising, the value of the once-a-week option is significant.

When you think about it, continuing a habit of exercising every Saturday for a year might have more real significance than creating a perfect exercise schedule and quitting after three weeks.

In health behavior, the "theoretically best method" and the "method that the individual can actually continue" are not always the same.

Once-a-week concentrated training could be a way to bridge that gap.