Weight Loss: The odds of success
The odds of long-term weight loss success can be confronting. For many people living with obesity, losing weight is not the hardest part — maintaining that weight loss over time is.
Approximately 1% of people with a body mass index over 30 maintain significant weight loss long term. This is a shocking statistic at first, but it is important to understand what it really means.
It does not mean change is impossible. It means that for many people, obesity is not simply a short-term lifestyle problem. It is a long-term medical condition affected by biology, hunger, hormones, environment, sleep, stress, time, and access to care.
The issue is not just losing weight. The issue is keeping it off in a body that may be trying to regain it.
Why the statistic feels so shocking
Medical Class 1 obesity can sometimes look, in everyday terms, like “just a few kilograms to lose”. For example, a person who is 150 cm and around 68 kg has a BMI of approximately 30. A person who is 160 cm and around 77 kg also has a BMI of approximately 30.
This can surprise people because many do not realise how early the medical category of obesity begins. A BMI over 30 is classified as obesity in adults, although BMI is a screening tool and should be considered alongside other health factors.
Why this matters:
- Obesity can begin earlier than people expect. It may not always look like what society imagines obesity to be.
- Weight regain is common. Many people can lose weight temporarily, but maintaining it is much harder.
- The body adapts. Hunger, metabolism, fullness signals, and energy expenditure can all change after weight loss.
- Long-term support matters. The more weight has been gained and regained, the more important structured support may become.
What the long-term study found
A major United Kingdom study used nearly a decade of electronic health records to examine the probability of people with obesity attaining normal body weight.
The study included health records from 278,982 people, including 129,194 men and 149,788 women. People who had bariatric surgery were excluded from the analysis, which means the study looked at outcomes without surgical intervention.
“During a maximum of 9 years’ follow-up, 1283 men and 2245 women attained normal body weight. In simple obesity, with a body mass index of 30.0–34.9 kg/m², the annual probability of attaining normal weight was 1 in 210 for men and 1 in 124 for women.”
“The annual probability decreased to 1 in 1290 for men and 1 in 677 for women with morbid obesity, with a body mass index of 40.0–44.9 kg/m².”
American Journal of Public Health, 2015 — Probability of an Obese Person Attaining Normal Body Weight: Cohort Study Using Electronic Health Records
This does not mean that no one can improve their health. Many people can reduce weight, improve blood pressure, improve blood sugar, sleep better, move better, and feel better. But the study shows that returning to a normal BMI and maintaining that result is uncommon without stronger intervention.
Why maintaining weight loss is so difficult
Weight regain is not simply a failure of discipline. After weight loss, the body can respond in ways that make maintenance harder. Hunger may increase, fullness may decrease, cravings may become stronger, and the body may burn fewer calories at rest.
This is sometimes called the body’s defence of weight. Your body may interpret weight loss as a threat and try to restore the weight that was lost.
After weight loss, some people experience:
- Increased hunger even when they are eating enough.
- Reduced fullness after meals.
- Lower resting energy expenditure, meaning the body may burn fewer calories.
- Stronger cravings and food reward signals.
- Faster regain when structure or restriction reduces.
- Emotional fatigue from feeling like weight control requires constant effort.
This is why many people can lose weight for a wedding, a holiday, a health scare, or a short-term goal — but struggle to maintain that loss for years.
What BMI category are you in?
BMI is calculated using weight and height. It does not measure body fat directly and does not account for muscle mass, body composition, ethnicity, age, or individual health history. However, it remains a commonly used screening tool.
Adult BMI categories:
- BMI 25–29.9: overweight
- BMI 30–34.9: Class 1 obesity
- BMI 35–39.9: Class 2 obesity
- BMI 40 and above: Class 3 obesity
The table below shows how BMI categories can look at different heights.
| Height | Weight | BMI | Obesity Class |
|---|---|---|---|
| 150 cm | 67.5 kg | 30.0 | Class 1 |
| 150 cm | 72 kg | 32.0 | Class 1 |
| 150 cm | 76.5 kg | 34.0 | Class 1 |
| 150 cm | 81 kg | 36.0 | Class 2 |
| 150 cm | 85.5 kg | 38.0 | Class 2 |
| 150 cm | 90 kg | 40.0 | Class 3 |
| 160 cm | 76.8 kg | 30.0 | Class 1 |
| 160 cm | 81.6 kg | 32.0 | Class 1 |
| 160 cm | 86.4 kg | 34.0 | Class 1 |
| 160 cm | 91.2 kg | 36.0 | Class 2 |
| 160 cm | 96 kg | 38.0 | Class 2 |
| 160 cm | 100.8 kg | 40.0 | Class 3 |
| 170 cm | 86.7 kg | 30.0 | Class 1 |
| 170 cm | 91.8 kg | 32.0 | Class 1 |
| 170 cm | 96.9 kg | 34.0 | Class 1 |
| 170 cm | 102 kg | 36.0 | Class 2 |
| 170 cm | 107.1 kg | 38.0 | Class 2 |
| 170 cm | 112.2 kg | 40.0 | Class 3 |
| 180 cm | 97.2 kg | 30.0 | Class 1 |
| 180 cm | 102.6 kg | 32.0 | Class 1 |
| 180 cm | 108 kg | 34.0 | Class 1 |
| 180 cm | 113.4 kg | 36.0 | Class 2 |
| 180 cm | 118.8 kg | 38.0 | Class 2 |
| 180 cm | 124.2 kg | 40.0 | Class 3 |
Class 1 obesity is still medically significant
Class 1 obesity may not always feel severe. A person may still work, exercise, parent, socialise, and live a full life. But medically, this is often the stage where action matters most.
At this point, some people still have the ability to lose weight and maintain it through lifestyle change, structure, education, medication, or early medical support. Waiting until weight, pain, sleep, or blood pressure worsen may reduce the number of simple options available.
Class 1 obesity is a warning sign, not a failure:
- It may be the first stage where long-term health risks begin to rise.
- It may still be early enough to change direction with the right support.
- It is the time to understand hunger, fullness, habits, and weight regain patterns.
- It is a chance to prevent progression into Class 2 or Class 3 obesity.
Why “just try harder” is not enough
Many people have already tried hard. They have dieted, exercised, tracked calories, skipped meals, joined gyms, taken medication, lost weight, and regained it.
The problem is that the body may respond to weight loss by increasing the drive to eat and reducing the energy it burns. Over time, this can make maintenance feel like a constant fight.
This is why weight regain should not be treated as a moral failure. It is often the predictable result of biology, environment, and insufficient long-term support.
Weight regain does not mean you failed. It may mean your treatment plan was not strong enough for the biology of the problem.
What should you take from this?
The statistic is not here to scare you. It is here to give context. If you have struggled to maintain weight loss, you are not unusual. You are part of a very common pattern.
The important question is not, “Why can’t I do this?” The better question may be, “What level of support do I actually need?”
You may need more support if:
- You have lost weight several times and regained it.
- Your hunger feels difficult to control.
- You do not feel full after eating.
- Your BMI is over 30 and increasing over time.
- You have weight-related health issues such as high blood pressure, sleep apnea, joint pain, or type 2 diabetes.
- You have used medication successfully but regained weight after stopping.
- Your quality of life is being affected by weight, pain, fatigue, or shame.
There is still hope
The odds may be difficult, but they are not a reason to give up. They are a reason to stop blaming yourself and start considering the right level of support.
Some people need better education. Some need structured lifestyle support. Some need medication. Some need surgery. Some need a combination of approaches.
What matters is choosing a pathway that matches your health, your history, your hunger, your weight trend, and your long-term goals.
You are not weak for needing help. You may simply need a stronger, more realistic plan.