Why Can't I Lose Weight?

The reasons you can’t lose weight fall into a short list, and the everyday ones are the easiest to check and fix. These are the reasons to work through:

• eating more than you record, through untracked snacks, oils, sauces and tastes while cooking
• portions that drift upwards over weeks
• strict weekdays followed by relaxed weekends
• calories from drinks, including alcohol, milky coffees, juice and sugary drinks
• too little protein
• too little muscle, and no strength training
• short or disrupted sleep
• stress
• some prescription medicines
• a medical condition such as an underactive thyroid

Mayo Clinic notes that off-and-on loosening of the rules contributes to stalled weight loss, and NHS Better Health warns that alcohol can be high in calories and easy to lose track of. A week of honest food and drink records, weighed where you can, is the quickest way to find the gap.

A calorie deficit means eating and drinking fewer calories than your body uses, and weight loss depends on keeping one. The NHS puts average use at around 2,000 calories a day for women and 2,500 for men, but your own figure depends on your size, age, muscle and activity. The free NHS Weight Loss Plan app lets you set a daily calorie target.

The deficit also shrinks as you lose weight. A smaller body burns fewer calories, so the amount that worked at the start may only hold your weight later (see weight loss plateau). Over several weeks, the scales and your waist are the honest test: if neither has moved, the deficit has closed.

Exercise helps, but what you eat and drink decides whether weight comes off. NHS Better Health puts it plainly: changing what you eat can help you lose weight, and moving more can help you keep the weight off. It is also easy to eat back what a session used, through a larger meal or a treat afterwards.

If you are exercising and dieting and nothing has moved for several weeks, check three things in turn: an honest week of food records, what you drink, and whether weekends match weekdays. If all three hold up, look at sleep, stress, medicines and the medical causes further down this page. An inability to lose weight despite diet and exercise, once those are checked, is a fair reason for a clinical assessment.

The scales weigh everything you carry, so fat loss can hide behind changes in fluid and muscle. Mayo Clinic explains that early weight loss is partly water released from glycogen, the carbohydrate stored in muscle and liver. Salty food makes the body hold fluid, and if you have started strength training you may be keeping or building muscle while you lose fat, so your weight falls more slowly than your shape changes.

Measure more than weight. Weigh at the same time each morning, after the toilet and in similar clothes, and watch the weekly trend. Measure your waist every couple of weeks: NICE advises keeping it to less than half your height. If your waist is falling, the fat that matters most is going, whatever the scales say that week.

Strength training and enough protein protect your muscle while you eat less, and muscle helps set how many calories you burn. Mayo Clinic notes that you lose some muscle along with fat as weight falls, and that less muscle means a slower metabolism. The NHS advises strengthening activities that work all the major muscle groups on at least 2 days a week, alongside 150 minutes of moderate activity a week.

Weights, resistance bands, body-weight exercises and carrying heavy shopping all count. For protein, include a proper portion at each meal, such as meat, fish, eggs, dairy, tofu, beans or lentils. The right amount for you depends on your size, age and training, and a registered dietitian can set it.

Poor sleep and stress can both make weight harder to lose. NHS Better Health says not getting enough sleep can make it harder to lose weight, because poor sleep may make you more likely to choose high calorie foods and too tired to exercise or cook. NHS Tayside adds that lack of sleep increases appetite, especially for foods high in fat and sugar.

Stress works through the same habits: the NHS lists eating too much or too little, sleeping badly and drinking more among its effects. If you snore loudly, wake a lot or feel very tired in the day, ask your GP about sleep apnoea, which the NHS links to obesity. Treatment can improve sleep and daytime tiredness, which makes the rest of a plan easier to keep.

If the everyday reasons have honestly been ruled out, a medical cause is worth looking for. The NHS lists these among the things that make a healthy weight harder to keep:

• an underactive thyroid, which also causes tiredness, feeling cold and constipation
• some prescription medicines
• perimenopause and menopause
• Cushing’s syndrome, which is rare
• depression or an eating disorder
• being over 55

Never stop a medicine without speaking to your prescriber. The blood tests for an inability to lose weight are ordinary ones: thyroid function, HbA1c, a lipid profile, liver and kidney function and a full blood count, at about £43 to £99 each in London. A normal set is still a useful result, because it moves the plan back to intake, muscle and sleep. The terms are explained in the weight management glossary, and if your weight is rising, see unexplained weight gain.

Speak to your GP before trying harder if any of these apply:

• weight rising even though you are eating very little
• tiredness, feeling cold or constipation alongside weight that will not shift
• swelling of the ankles, legs or tummy
• loud snoring and feeling very tired during the day
• weight gain that began after starting a new medicine

If you find yourself cutting food further and further, feel out of control around food, or your weight is causing you distress, speak to your GP or contact Beat, the eating disorder charity, on 0808 801 0677. Each of these needs support before any change to your diet.

A first assessment arranged by Medical Weight Loss London at UNTIL Soho looks at why weight will not shift for you in particular. It goes through what you eat, drink and do in a typical week, your sleep and every medicine you take. It measures weight, waist and blood pressure and arranges thyroid function, HbA1c, a lipid profile, liver and kidney function and a full blood count. First assessments at London clinics cost about £150 to £310, with tests on top (what a programme costs).

The results shape a medical weight loss programme with regular reviews. Ask what to get checked and UNTIL Health Concierge arranges the appointment with a registered clinician.