Dr. Yi-Cheng Wu
中文

Obesity: An Overview and Exercise Prescription

By Dr. Yi-Cheng Wu · Reviewed June 21, 2026

Obesity is a disease associated with many chronic conditions; a calorie-deficit diet combined with aerobic and resistance exercise, done progressively, is the research-supported approach.

Obesity is regarded as a disease, and many countries have developed treatment guidelines. In Taiwan, a BMI of 24 or above is used as the cutoff for overweight and 27 or above for obesity, alongside body-fat percentage and waist circumference. Research shows obesity is associated with type 2 diabetes, cardiovascular disease, osteoarthritis, and other conditions. Treatment proceeds step by step according to the individual: first lifestyle changes, dietary control, and exercise, and only when necessary are medication or surgery considered. Diet centers on a calorie deficit, while exercise combines aerobic and resistance training.

Stepwise treatment process for obesity (6 steps)

  1. Physical assessment and basic measurements

    Start with a physical assessment and basic measurements. Common methods include BMI, estimating body-fat percentage with DXA or bioelectrical impedance, and waist circumference. In Taiwan, a BMI of 24 or above is the cutoff for overweight and 27 or above for obesity, interpreted together with body-fat percentage.

  2. Correct lifestyle and risk factors

    Before medication or surgery, begin with lifestyle: adjust daily routine and activity level, and address obesity-related risk factors such as high blood sugar, high blood lipids, and high blood pressure.

  3. Center dietary control on a calorie deficit

    Diet is the most powerful way to counter obesity. First understand your basal metabolic rate (BMR) and total daily energy expenditure (TDEE); the principle is to burn more calories each day than you take in (a calorie deficit), choosing more healthy whole foods and avoiding extreme diets that work quickly but tend to lead to weight regain.

  4. Add aerobic and resistance exercise, progressing gradually

    The exercise prescription includes both aerobic and resistance training. People with obesity often have low exercise capacity, so it is suggested to start at a low load (about 2-3 METs) and increase by small increments (about 0.5-1 MET) at each stage; over the long term, time spent at moderate-to-high intensity can be gradually increased.

  5. Set trackable staged goals

    Exercise and weight-loss goals can be designed with the SMART principles (specific, measurable, attainable, realistic, trackable), and weight-loss targets set at roughly 3-10% of body weight over 3-6 months, with the first 3-6 months being especially important.

  6. Consider medication or surgery only when necessary

    After completing the above assessment and diet and exercise interventions, medication or bariatric surgery is considered only if the situation calls for it, and exercise must continue after surgery to maintain the weight-loss effect. Medication and surgery are individualized medical decisions that must be assessed by a physician based on your personal situation.

Is obesity a disease?

Yes. Every disease can lead to different consequences, so experts around the world write different treatment guidelines for each one, and obesity is no exception. From the United States, Canada, the UK and Europe, to Japan and South Korea, each has its own guidelines tailored to national needs. The old idea that being able to eat well is a blessing no longer always applies today. Research has confirmed that being overweight and obese brings many problems, and surveys in recent years show a rising proportion of obese people in Taiwan, a hidden crisis that will affect the whole nation’s health level in the future.

Originally published in Commonhealth Magazine

How obesity is diagnosed

Common methods include body mass index (BMI), estimating body-fat percentage through dual-energy X-ray absorptiometry (DXA) or bioelectrical impedance analysis (BIA), and waist circumference measurement. Because each country has to consider its overall mortality, epidemiology, cross-sectional surveys, and cohort follow-up studies, the standards for diagnosing overweight and obesity differ from country to country. Taiwan, for example, uses a BMI of 24 kg/m² or above and 27 kg/m² or above as the diagnostic cutoffs for overweight and obesity, respectively, in Taiwanese adults.

Interpreting BMI

There are research-supported cutoff values for diagnosing obesity by body-fat percentage, but the body fat measured by different devices varies too much and changes with age and measurement conditions, making it hard to provide a clear consensus cutoff for diagnosing overweight and obesity. Waist circumference represents abdominal fat to some degree; although there are defined measurement procedures, there is currently no firm conclusion on using waist circumference, waist-to-hip ratio, or waist-to-height ratio as an assessment method.

HPA BMI calculator

Toolbxs BMI calculator

BMI tells us a lot, but some things cannot be judged by BMI alone, so looking at body-fat percentage together with it is helpful. For example, fitness enthusiasts who care about their physique often exceed the BMI threshold, usually because high muscle mass raises BMI, and their body fat is typically low. On the other hand, some people have a normal BMI but high body fat, the skinny-fat type (body fat of 25% or above in men, 30% or above in women), who watch their diet but lack exercise, especially strength training. Obese body shapes differ by sex. In men, fat cells enlarge mainly around the waist, so middle-aged men with obesity gain a belly, while in women the fat cells are usually below the waist, closer to the buttocks and thighs, resembling a pear shape.

Obesity and disease

Obesity is associated with diabetes and increases the chance of developing type 2 diabetes. According to research abroad, changing eating and exercise habits can delay the possible progression of diabetes, lowering the risk ratio by 40-60%. A 5% drop in body weight can bring down blood sugar and glycated hemoglobin; people with obesity and diabetes should aim to lose 7-10% of body weight, reduce daily calorie intake by 500-1000 kcal, and lose weight at a rate of 0.5-1 kg per week to achieve weight loss and improve blood sugar.

Obesity increases cardiovascular disease risk, such as high blood sugar, high blood lipids, high blood pressure, and metabolic syndrome. Research shows that men with obesity have a 40% higher risk of death from cardiovascular disease compared with those of normal weight, and women 53% higher. Other conditions such as osteoarthritis, sleep apnea, depression, fatty liver, infertility, and gastroesophageal reflux are also associated with obesity.

For example, being overweight and obese is associated with roughly 2.5 and 4.5 times the risk of knee osteoarthritis respectively, in a dose-response relationship, meaning the heavier the body weight, the higher the risk. Obesity also affects sperm motility; research abroad found that men with a normal BMI had 18.6 million motile sperm per milliliter, overweight men 3.6 million, and men with obesity 0.7 million, a very rapid decline. It is not only men; obesity also causes many reproductive-system conditions in women, including infertility, irregular periods, and miscarriage, and polycystic ovary syndrome is strongly related to obesity.

Medications for treating obesity work through mechanisms that make people feel full and reduce the body’s absorption of fat. For patients with a BMI between 27-30 or above accompanied by the three highs (high blood sugar, lipids, and pressure), medication may help with weight loss, and more severe cases may undergo surgery such as gastric banding, gastric bypass, or sleeve gastrectomy.

A complete obesity treatment process includes physical assessment, basic measurements, lifestyle correction, correcting risk factors, dietary control, and exercise guidance, with medication or surgery coming only last. The effort in the first 3-6 months is very important; many people who commit to it reach their ideal goal through diet and exercise within 3-6 months.

Dietary intervention

Diet is still the most powerful weapon against obesity. To improve obesity, you first need to understand two numbers.

Basal metabolic rate (BMR) is the minimum energy the body needs to expend at rest, estimated from the sex, age, weight, and height you enter; it is a predicted value based on statistics from past data.

Total daily energy expenditure (TDEE) estimates the calories needed for daily life, calculated mainly from BMR and your usual activity level. For people who sit for long periods at work and don’t exercise, TDEE equals BMR times 1.2; for people who do light exercise 1-3 days a week, TDEE equals BMR times 1.375, increasing step by step up to a maximum for professional athletes who train twice a day, whose TDEE equals BMR times 2.

Both formulas can be broken down in great detail, but understanding the general idea and recording consistently is actually more important. Here is a conversion website for reference.

Toolbxs BMR and TDEE calculator

There are many methods of dietary intervention, and the market offers a wide range, including ketogenic diets, low-carb diets, intermittent fasting, gluten-free diets, low-GI diets, changing gut flora, meal-replacement weight loss, and even taking various diet drugs. In fact, the healthiest and most research-supported approach is still a calorie deficit, meaning that daily calorie expenditure is higher than calorie intake. Some extreme methods produce fast weight loss but lack sustainability and are prone to weight regain. Based on personal food preferences, degree of obesity, and health status, there are different combinations; as long as you follow the calorie-deficit principle (negative energy balance) and choose more healthy whole foods, you can lose weight steadily.

Exercise prescription

Exercise offers more than weight-loss benefits; it also reduces weight regain, lowers body fat and visceral fat, and reduces the occurrence of cardiovascular disease and mortality. Relying on exercise alone for weight loss is less effective — an hour of moderate-intensity exercise burns only 300-400 kcal, and one kilogram of body fat (about 7700 kcal) takes more than 20 hours to burn off — so combining it with dietary intervention makes the results more noticeable.

Current research suggests that both aerobic and resistance exercise are helpful. If you can’t exercise for long stretches, using scattered pockets of time can still capture some of the benefits of exercise. High-intensity interval training has been a hot topic of discussion in recent years.

High-intensity interval training (HIIT) has risen in popularity in recent years and was previously used in professional sports training. Its main definitions include high exercise intensity at 80-100% of maximum heart rate, short bursts of maximal-intensity aerobic effort lasting 1-4 minutes, and separating these with active recovery or static rest. HIIT can combine muscle and cardiopulmonary training, has some effects on promoting post-exercise afterburn and hormone secretion, and a small number of studies have suggested it may reduce appetite after exercise.

Looking only at fat-loss outcomes, short-term high-intensity interval training is not superior to moderate-intensity aerobic exercise for fat loss. However, from a time perspective, high-intensity interval training may take nearly 40% less time than moderate-intensity aerobic exercise, making it a more efficient way to lose weight. Strength training also offers benefits of saving time, an afterburn effect, and building muscle while losing fat.

Beyond the FITT content of an exercise prescription, the design can use the five SMART principles.

  • Specific — tailored to the individual
  • Measurable — can be measured
  • Attainable — possible to achieve
  • Realistic — matches reality
  • Trackable — can be followed up

The American College of Sports Medicine offers several recommendations for exercise considerations in patients with obesity.

  • For people with obesity, exercise testing is usually not required before starting a low-to-moderate-intensity exercise program
  • For patients using beta-blockers or diabetes medications, pay attention to the timing of exercise relative to medication
  • People with obesity mostly have low exercise capacity, so it is suggested to start with a low load (2-3 METs) and increase by small increments (0.5-1 MET) at each stage
  • Set short-term and long-term weight-loss goals, suggested at 3-10% of body weight over 3-6 months
  • A low-calorie diet with daily intake under 1,500 kcal can produce greater weight loss in the initial phase, but this dietary approach only suits selected people and is recommended for short-term use
  • After the initial weight-loss phase, strengthen communication among medical experts, dietitians, exercise trainers, and the patient with obesity
  • Total activity can be accumulated using bouts of moderate-intensity physical activity greater than 10 minutes each or other varied types
  • To maintain long-term weight-loss results, gradually increase moderate-to-high-intensity exercise time to more than 250 minutes per week

A small number of people with a BMI of 40 kg/m² or above, or a BMI of 35 kg/m² or above with risk factors, may consider bariatric surgery, but post-operative care still includes exercise. Research confirms that exercising after surgery can strengthen and maintain the weight-loss effect. Finishing the operation is not the end of everything, but another beginning.

Summary

Solving overweight and obesity is not hard — there are no secret remedies and no instant results. If something claims otherwise, it is very likely a scam or harmful to the body. Through a healthy diet and persistent exercise, you can return to a healthy body without spending a large amount of money.

Further reading

Exercise prescription for hypertension

Exercise prescription for dyslipidemia

Exercise prescription for diabetes

Further reading

Frequently asked questions

Is obesity a disease?

Yes, obesity is regarded as a disease, and many countries — including the United States, Canada, the UK and Europe, Japan, and South Korea — have developed treatment guidelines tailored to their own populations. Research confirms that being overweight and obese brings many health problems.

How is obesity diagnosed?

Common methods include body mass index (BMI), estimating body-fat percentage with DXA or bioelectrical impedance analysis, and waist circumference measurement. In Taiwan, a BMI of 24 kg/m² or above is the diagnostic cutoff for overweight in adults, and 27 kg/m² or above for obesity.

How should I interpret BMI?

BMI provides a lot of information, but some situations cannot be judged by BMI alone, so looking at body-fat percentage together with it is helpful. For example, fitness enthusiasts with high muscle mass often have a high BMI but low body fat, while people with a normal BMI but high body fat (25% or above in men, 30% or above in women) fall into the skinny-fat category.

What disease risks does obesity increase?

Obesity is associated with type 2 diabetes, cardiovascular disease, osteoarthritis, sleep apnea, fatty liver, and reproductive problems. Research shows that being overweight and obese is associated with roughly 2.5 and 4.5 times the risk of knee osteoarthritis respectively, in a dose-response relationship.

How should diet be used to address obesity?

The most research-supported approach is a calorie deficit — that is, burning more calories each day than you take in. It helps to first understand your basal metabolic rate (BMR) and total daily energy expenditure (TDEE), and to choose more healthy whole foods. Extreme diets can produce fast weight loss but are harder to sustain and more prone to weight regain.

This article is also available in the original Chinese, with the full reference list.

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