Weight Management: The Complete Guide to Losing Weight Safely and Keeping It Off

More than one billion people worldwide are now living with obesity, according to a 2024 analysis published in The Lancet. Most of them have tried to lose weight, often many times. If that is you, the problem is not a lack of willpower. Weight is shaped by biology, environment, sleep, stress, medicines and money as much as by personal choices. Understanding this is the first step to an approach that actually works.

This guide covers how to assess your weight, why weight loss is hard and weight regain is common, the eating and activity approaches with the best evidence, the new generation of weight-loss medicines, surgery, and practical strategies to keep weight off.

Why weight matters for health

Excess weight, particularly around the waist, raises the risk of type 2 diabetes, high blood pressure, heart disease, stroke, fatty liver disease, sleep apnoea, osteoarthritis, some cancers (including bowel, breast after menopause, womb and kidney), fertility problems, and complications in pregnancy. It can also affect mood, self-esteem and mobility.

The encouraging news is that modest weight loss brings real benefits. Losing 5 to 10 percent of body weight can lower blood pressure, improve blood sugar, reduce knee pain, improve sleep apnoea and reduce liver fat. In people with recently diagnosed type 2 diabetes, losing around 15 kilograms can put diabetes into remission for many.

How to assess your weight

Body mass index (BMI)

BMI is your weight in kilograms divided by your height in metres squared. For most adults:

• Under 18.5: underweight
• 18.5 to 24.9: healthy weight
• 25 to 29.9: overweight
• 30 to 39.9: obesity
• 40 or more: severe obesity

People of South Asian, Chinese, other Asian, Middle Eastern, Black African and African-Caribbean backgrounds have a higher risk of type 2 diabetes and heart disease at a lower BMI. Many guidelines use lower thresholds for these groups, for example treating a BMI of 23 as overweight and 27.5 as obesity.

Waist measurement

BMI does not show where fat is stored. Fat around the organs (visceral fat) is the most harmful. A simple check is the waist-to-height ratio: your waist should be less than half your height. Measure your waist halfway between your lowest rib and the top of your hip bone, after breathing out normally.

Beyond the numbers

In 2025, a Lancet Commission proposed defining “clinical obesity” based not only on BMI but on whether excess body fat is already affecting organs or daily function. This reflects a growing view that health, not weight alone, should guide treatment.

Why losing weight is hard

• Biology: when you lose weight, levels of hunger hormones such as ghrelin rise and fullness hormones fall. Your body also burns fewer calories than expected. These changes can persist for years.
• Genetics: genes influence appetite, how full you feel and where you store fat. Twin studies suggest genes explain a large share of differences in weight between people.
• Environment: cheap, heavily marketed, ultra-processed foods, large portions, sedentary jobs and car-dependent neighbourhoods make weight gain easy.
• Sleep and stress: short sleep and chronic stress increase appetite and cravings.
• Medicines: some antidepressants, antipsychotics, steroids, insulin, some diabetes medicines and some epilepsy medicines can cause weight gain.
• Medical conditions: an underactive thyroid, polycystic ovary syndrome (PCOS), Cushing’s syndrome and menopause can contribute.
• Life events: pregnancy, quitting smoking, injury, shift work and caring responsibilities.

Weight stigma, being blamed or shamed for your weight, is common, including in healthcare. It does not motivate people; it increases stress, comfort eating and avoidance of care. You deserve respectful support.

Setting realistic goals

A realistic initial goal for most people is to lose 5 to 10 percent of body weight over three to six months, at a pace of about 0.5 to 1 kilogram a week. Then focus on maintaining that loss. Goals that focus on behaviours, such as “walk for 20 minutes after dinner five days a week”, are often more helpful than weight targets alone.

Eating for weight loss: what works

To lose weight, you need to take in less energy than you use over time. But how you achieve that matters for hunger, health and sustainability. Many eating patterns can work; the best is one you can stick to.

Principles with good evidence

• Fill half your plate with vegetables and salad, a quarter with protein, and a quarter with whole grains or starchy foods.
• Prioritise protein at each meal (fish, eggs, beans, lentils, chicken, yoghurt, tofu). Protein helps you feel full and preserves muscle.
• Choose high-fibre foods such as whole grains, beans, vegetables, fruit, nuts and seeds.
• Limit ultra-processed foods such as crisps, sweets, biscuits, sugary cereals and fast food. A controlled trial at the US National Institutes of Health found that people ate around 500 more calories a day on an ultra-processed diet than on an unprocessed one.
• Cut sugary drinks, including fizzy drinks, energy drinks, sweetened tea and coffee, and large fruit juices. Water, unsweetened tea and coffee are best.
• Watch portions, using smaller plates and serving food in the kitchen rather than at the table.
• Limit alcohol, which is high in calories and increases appetite.
• Eat regularly and avoid skipping meals if it leads to overeating later.

Popular approaches

• Mediterranean-style eating: rich in vegetables, olive oil, fish and legumes; good for weight and heart health.
• Lower-carbohydrate diets: can work well for some people, especially those with type 2 diabetes. Check with your healthcare provider if you take diabetes medicines, as doses may need adjusting.
• Intermittent fasting or time-restricted eating: such as 5:2 or eating within an 8 to 10 hour window. Studies show similar results to daily calorie reduction; it suits some people but not others.
• Total diet replacement (low-energy diets): soup and shake programmes of around 800 to 1,200 calories a day for 8 to 12 weeks, with medical supervision. These can produce large weight losses and diabetes remission, as shown in the DiRECT trial.
• Commercial programmes: group-based programmes can be effective and provide support.

What to avoid

• Very restrictive “detox” or “cleanse” diets
• Weight-loss teas, pills and supplements sold online, which may contain dangerous hidden ingredients
• Diets that cut out entire food groups without a medical reason
• Very low calorie diets without supervision, especially if you take medicines

Physical activity

Exercise alone usually produces modest weight loss, but it is extremely important for health, mood, sleep, preserving muscle during weight loss and, crucially, keeping weight off. People who maintain weight loss long term are typically very active.

• Aim for at least 150 to 300 minutes of moderate activity a week, such as brisk walking
• Do strength exercises at least twice a week
• Reduce sitting time and break it up regularly
• Start where you are; even 10-minute walks count
• Find something you enjoy: dancing, cycling, swimming, football, gardening

Step counts are a useful target. Research suggests health benefits increase with steps up to around 7,000 to 10,000 a day, but any increase from your current level helps.

Sleep, stress and mood

Adults who regularly sleep less than seven hours tend to eat more and gain more weight. Aim for seven to nine hours with a regular routine. Managing stress through exercise, relaxation, social support or therapy can reduce emotional eating. If you binge eat, feel out of control around food, or use food to cope with difficult emotions, talk to a healthcare provider; binge eating disorder is common and treatable.

Behaviour change strategies that work

• Self-monitoring: keeping a food diary or using an app, and weighing yourself regularly (weekly or even daily), are strongly linked to success.
• Planning: plan meals and snacks, write a shopping list, and batch-cook healthy meals.
• Changing your environment: keep tempting foods out of sight or out of the house, and keep fruit and vegetables visible.
• Mindful eating: eat slowly, without screens, and notice hunger and fullness.
• Problem-solving: plan ahead for difficult situations such as parties, travel and night shifts.
• Support: involve family or friends, or join a group programme.
• Self-compassion: lapses are normal. One bad day does not undo progress.

Weight-loss medicines

For people with obesity, or overweight with weight-related health problems, medicines can be an effective addition to diet and activity. The newest medicines mimic gut hormones that reduce appetite and increase fullness.

• Semaglutide (Wegovy): a weekly injection; in trials, people lost around 15 percent of body weight on average over about 68 weeks. It has also been shown to reduce heart attacks and strokes in people with heart disease and overweight.
• Tirzepatide (Mounjaro, Zepbound): a weekly injection acting on two hormone pathways; average losses of around 20 percent in trials.
• Liraglutide (Saxenda): a daily injection with smaller average losses; generic versions are becoming available.
• Orlistat: a tablet that reduces fat absorption; modest effect, with gastrointestinal side effects.
• Naltrexone-bupropion and phentermine-topiramate: available in some countries.

Common side effects of GLP-1 medicines include nausea, vomiting, diarrhoea, constipation and reflux, usually during dose increases. Rare but serious risks include pancreatitis and gallbladder problems. They are not used in pregnancy. Weight is usually regained if the medicine is stopped without lasting lifestyle changes, so many people may need long-term treatment. Muscle loss can occur, so eating enough protein and doing strength exercise are important.

Only use these medicines when prescribed by a licensed healthcare provider and supplied by a regulated pharmacy. Fake and compounded versions sold online have caused serious harm. In 2025, WHO added GLP-1 medicines to its guidance on obesity treatment and its list of essential medicines for some indications, which may improve access worldwide.

Weight-loss (bariatric) surgery

Surgery is the most effective long-term treatment for severe obesity. It is usually considered for people with a BMI of 40 or more, or 35 or more with conditions such as type 2 diabetes (lower thresholds apply in some groups). Common operations include sleeve gastrectomy and gastric bypass.

People typically lose 20 to 30 percent of body weight, and many see type 2 diabetes go into remission, along with improvements in blood pressure, sleep apnoea and life expectancy. Surgery requires lifelong changes in eating, vitamin and mineral supplements, and follow-up. Risks include surgical complications, nutritional deficiencies, and in some people, problems with alcohol or mood. Surgery abroad without proper follow-up can be risky.

Keeping weight off

Weight maintenance is where most efforts fail, and it deserves as much attention as weight loss. People in the US National Weight Control Registry, who have kept off at least 13.6 kilograms for a year or more, commonly report:

• High levels of physical activity, often around an hour a day
• Eating breakfast most days
• Weighing themselves at least weekly
• Watching less television
• Eating a consistent diet across weekdays and weekends
• Catching small regains early and acting quickly

Set a “trigger weight”, such as 2 kilograms above your goal, at which you return to more structured habits.

Special situations

Shift workers

Night shifts disrupt hunger hormones and make healthy eating harder. Plan meals before your shift, eat your main meal before starting, choose light, protein-rich snacks during the night, avoid sugary vending machine food, and protect your sleep.

Menopause

Hormonal changes shift fat towards the waist. Strength training, protein, sleep and managing symptoms (including with HRT where appropriate) can help.

Older adults

Weight loss in older age should focus on preserving muscle and strength. Unintentional weight loss in older people should always be checked.

Children

For children, the focus is usually on healthy family habits rather than dieting. Involve the whole family, avoid labelling foods as “good” or “bad”, and seek support from a child health service.

Common myths

• Myth: It is all about willpower. Fact: Biology and environment play huge roles.
• Myth: Eating late at night causes weight gain. Fact: Total intake matters more than timing for most people.
• Myth: Carbs make you fat. Fact: Excess calories from any source cause weight gain; whole-grain carbohydrates are healthy.
• Myth: You can spot-reduce belly fat with sit-ups. Fact: You cannot choose where fat is lost.
• Myth: Weight-loss injections are “the easy way out”. Fact: Obesity is a medical condition, and using effective treatment is not a moral failing.

The nurse’s role

Nurses are often the first to raise weight with patients, run weight management clinics, support people on weight-loss medicines, prepare patients for bariatric surgery and provide long-term follow-up. Raising the topic sensitively, asking permission, using person-first language and focusing on health rather than appearance make conversations more helpful.

A sample day of eating

There is no single perfect menu, but this example shows how balanced, filling meals can fit together. Adjust portions to your needs and your culture’s foods.

• Breakfast: two eggs with tomatoes and spinach and a slice of wholegrain bread, or plain yoghurt with berries and a spoonful of nuts, or oats cooked with milk and topped with fruit.
• Lunch: a large salad or vegetable soup with beans, lentils, chicken or fish, and a small portion of brown rice, quinoa or wholegrain bread.
• Snack (if hungry): a piece of fruit, a small handful of unsalted nuts, carrot sticks with hummus, or a boiled egg.
• Dinner: grilled fish, chicken, beans or tofu with half a plate of vegetables and a modest portion of potatoes, rice, yam, plantain or pasta.
• Drinks: water, sparkling water, unsweetened tea or coffee throughout the day.

Traditional diets in many parts of the world, built around vegetables, legumes, whole grains and modest amounts of meat or fish, are naturally well suited to weight management. Problems tend to arise when they are replaced by sugary drinks, fried snacks and processed foods.

Eating out, celebrations and social pressure

Weight management has to fit into real life, including weddings, festivals, birthdays, business lunches and family meals where refusing food can feel rude.

• Plan ahead: have a light, protein-rich meal earlier in the day rather than arriving starving
• Fill your plate with vegetables and protein first, and take smaller portions of rich dishes
• Alternate alcoholic drinks with water, or choose low- and no-alcohol options
• Eat slowly and put your fork down between bites
• Have a polite phrase ready, such as “It was delicious, I am happily full”
• Enjoy special occasions without guilt; what matters is what you do most of the time

Tracking progress beyond the scale

The scale is only one measure, and it can be frustrating because weight naturally fluctuates by one to two kilograms from day to day with water, salt, hormones and digestion. Other measures can show progress even when the scale does not move:

• Waist measurement and how clothes fit
• Blood pressure, blood sugar (HbA1c) and cholesterol results
• Fitness, such as how far you can walk or how many stairs you can climb without getting breathless
• Strength, energy, sleep quality and mood
• Reduced joint pain
• Fewer medicines needed

If you weigh yourself, do it at the same time of day, under the same conditions, and look at the trend over weeks rather than any single reading.

When weight gain needs medical checks

See a healthcare provider if you gain weight rapidly without changes in eating or activity, or if weight gain comes with symptoms such as tiredness, feeling cold, constipation and dry skin (possible underactive thyroid), irregular periods and excess hair growth (possible PCOS), swelling of the legs or breathlessness (possible fluid retention from heart, kidney or liver problems), or easy bruising, purple stretch marks and muscle weakness (possible Cushing’s syndrome). Also ask for a review if you think a medicine is causing weight gain; there may be alternatives, but never stop a prescribed medicine without advice.

Supporting a family member

If someone you love is trying to manage their weight, the most helpful things are encouragement, practical help and joining in, rather than comments about their body or what they eat. Cook healthy meals together, go for walks as a family, keep fewer tempting foods in the house, and celebrate efforts rather than numbers on the scale. Criticism and “food policing” usually backfire.

Frequently asked questions

How fast should I lose weight?

About 0.5 to 1 kilogram a week is safe for most people. Faster loss may happen early or on supervised programmes.

Why have I stopped losing weight?

Plateaus are normal as your body adapts. Review portions, activity and sleep, and be patient. Sometimes maintaining for a while before continuing helps.

Should I count calories?

It helps some people, especially at first. Others do better focusing on portions and food quality.

Do I need supplements?

Most people do not, unless they have had bariatric surgery, follow a restrictive diet or have a deficiency.

Can I get weight-loss injections without seeing anyone?

You should only take them after an assessment by a licensed healthcare provider, with ongoing monitoring.

But I have failed so many times. Why would this time be different?

Because you are not starting from failure; you are starting from experience. You now know which approaches did not last for you. This time, aim for changes you could keep for life, focus on health gains rather than speed, protect your sleep, build activity you enjoy, get support, and consider medical treatment if you qualify. Weight management is a long-term condition, not a short project, and every step counts.

Related: Calorie deficit explained · Weight-loss injections explained · Walking for weight loss · Type 2 diabetes guide

Sources: World Health Organization (obesity fact sheet and 2025 guidance on GLP-1 therapies), NCD Risk Factor Collaboration (The Lancet, 2024), The Lancet Diabetes & Endocrinology Commission on clinical obesity (2025), National Institute for Health and Care Excellence (obesity guidance), DiRECT trial, STEP and SURMOUNT trials, US National Weight Control Registry.