Why does weight come back after weight loss?

How common is weight regain?

Weight regain is very common after any type of treatment, which shows how strong the biology behind obesity is. After lifestyle programmes, many people slowly regain part of the weight over the following years. After stopping weight-loss medicines, regain is often faster.

A recent review in The BMJ of 37 studies estimated that weight was back at the starting level about 1.5 years after stopping the newer medicines, and that regain after stopping lifestyle programmes was slower.

Long-term results are better than many people think. A review of 29 US studies found that, five years after a structured programme, the average person still weighed more than 3 kg less than at the start.

Another review estimated that about one in five people with overweight manage to lose at least 10% of their weight and keep it off for at least a year. Members of the US National Weight Control Registry had lost 33 kg on average and kept it off for more than five years.

Why does weight regain happen?

Weight regain happens because the brain and body respond to weight loss as a threat and try to restore the lost weight. Several changes work together.

Appetite hormones change

After weight loss, levels of hormones that signal fullness, such as leptin, go down, and levels of the hunger hormone ghrelin go up. In an Australian study, 50 adults lost about 13 kg on a very low energy diet. One year later, their hormones were still shifted in a way that increases appetite, and they had regained about 5 kg on average.

People feel hungrier and think more about food, even when they eat the same as before.

The body uses less energy

A smaller body needs less energy, but the drop is often larger than expected. This is called metabolic adaptation. In a study of 14 contestants from a TV weight-loss competition, their resting metabolism was still about 700 kcal a day lower than at the start six years later, and about 500 kcal a day lower than expected for their body size.

That study involved extreme weight loss, but smaller adaptations happen in most people.

Life and environment

Stress, poor sleep, illness, some medicines, life events and an environment full of cheap, energy-dense food all make it harder to maintain weight. Read more about the food environment and medicines that can cause weight gain.

Which reasons for regain are common, and what helps with each?

Most weight regain has a few common reasons, and each one has its own practical answer. Talk to your doctor first before you change your eating or exercise plan, especially if you have a health condition or take medicines.

The support effect comes from a review of 45 trials with 7,788 adults. Programmes that worked on both food and physical activity led to about 1.6 kg less regain after 12 months than in the comparison groups.

That may sound small, but it adds up over the years. It is also a reason to stay in touch with your care team when things are going well.

Is weight regain a failure?

No, weight regain is not a failure: it is the expected course of a chronic disease when treatment stops or is not strong enough. Think of high blood pressure. If blood pressure rises after stopping a medicine, nobody calls that a personal failure. The same applies to obesity.

Feeling guilty or ashamed often makes things harder, and stigma can lead people to avoid care. See weight stigma.

Remember that the health benefits of weight loss count, even if some weight returns. Every period of better blood sugar, blood pressure, fitness or mood has value.

Why is obesity treated as a chronic disease?

Obesity is treated as a chronic disease because the biology that drives it does not go away after weight loss. An international commission in The Lancet Diabetes and Endocrinology, endorsed by more than 75 medical organisations, has defined clinical obesity as a chronic illness that needs timely, evidence-based care. Read more about clinical obesity.

In practice, this means:

• plan for maintenance from the start, not only for the weight-loss phase;
• keep in regular contact with your care team, also when things go well;
• adjust treatment when weight starts to rise, instead of waiting.

What helps to maintain weight loss?

The strongest evidence for maintaining weight loss is for ongoing support combined with regular physical activity, such as daily walking, good food and regular self-monitoring. Strategies with good evidence include:

• Continued contact with a professional or programme, in person, by phone or online.
• Regular physical activity. People who keep weight off are often active for about an hour a day, mostly walking. Any amount helps: start with short daily walks and build up. Strength training, such as our free workouts, helps protect muscle.
• Self-monitoring. Weighing yourself regularly, for example once a week, helps you notice small changes early. If weighing makes you anxious, agree on another approach with your care team.
• A regular eating pattern with enough protein and fibre, which helps manage hunger.
• Good sleep and stress management.
• A plan for difficult times, such as holidays, illness or stressful periods.

In the US National Weight Control Registry, people who lost at least 13.6 kg (30 pounds) and kept it off for at least a year commonly report these habits. See lifestyle treatment for more.

What about medication and weight regain?

Weight usually returns when weight-loss medication is stopped. In the STEP 1 extension, people had regained about two-thirds of their weight loss one year after stopping semaglutide. Continuing a medicine for a long time means ongoing costs, the possibility of side effects and questions that long-term research has not yet answered.

Rules on access and reimbursement differ by country. Read the facts on our page about weight-loss medication.

Whether medication is right for you is something to discuss with your own doctor. Obesity Foundation does not recommend or promote weight-loss medication. We focus on good food, appropriate exercise and walking, habits that help you whether or not you ever use medication.

How can you restart treatment?

You can restart treatment at any time, and it is best to seek help early, when weight starts to rise. Steps that can help:

1. Make an appointment with your doctor or care team. Say clearly that you want help with weight regain.
2. Look at what changed. New medicines, stress, sleep problems, illness or life events can all play a role.
3. Review your options. This could be a new lifestyle programme, a dietitian, psychological support, a return to daily walks and regular exercise, or a review after bariatric surgery. Your doctor can also talk you through medical options.
4. Set realistic goals. Preventing further gain is already a success.