What is BMI?

BMI (Body Mass Index) is a calculation based on your height and weight. It helps assess whether your weight may be affecting your health.

For most adults:

• Healthy weight: BMI 18.5-24.9
• Overweight: BMI 25-29.9
• Obesity: BMI 30 or above

BMI is not perfect and may be less accurate for very muscular individuals or some ethnic groups. However, it remains a useful screening tool when assessing eligibility for weight loss treatment.

Why does BMI matter?

A higher BMI is associated with an increased risk of health conditions including:

• Type 2 diabetes
• High blood pressure
• Heart disease
• Stroke
• Sleep apnoea
• Osteoarthritis
• Some cancers

Losing weight can help reduce these risks and improve overall health.

What is the cause of weight gain and obesity?

Weight gain occurs when more calories are consumed than the body uses. However, obesity is a complex condition influenced by many factors, including:

• Genetics
• Appetite regulation
• Lifestyle and physical activity
• Mental wellbeing
• Certain medical conditions
• Some medicines

For many people, obesity is not simply a matter of willpower, which is why medical treatments may sometimes be appropriate.

Can medicines cause weight gain?

Yes. Some medicines can contribute to weight gain, including certain:

• Antidepressants
• Antipsychotics
• Diabetes treatments
• Steroid tablets
• Epilepsy medicines
• Beta blockers

If you think your medication may be affecting your weight, discuss this with your doctor before making any changes.

What is the best diet for weight loss?

There is no single ‘best’ diet. The most effective eating plan is one that you can maintain long term, but eating a healthy, balanced diet is recommended to aid weight loss.

This should include:

• Plenty of fruit and vegetables
• High-fibre foods
• Lean protein
• Wholegrains
• Reduced intake of highly processed foods
• Limiting sugary drinks and excess alcohol

How much weight can I lose with GLP-1 medication?

Results vary between individuals. Weight loss depends on factors such as your starting weight, diet, exercise levels and adherence to treatment.

Clinical studies have shown that people using GLP-1 medications alongside lifestyle changes can achieve significant weight loss over time. The best results are seen when treatment is combined with long-term healthy eating and increased physical activity.

How long will I need to take GLP-1 treatment?

GLP-1 medications are intended for long-term weight management, but the length of treatment varies between individuals.

Some people continue treatment long term because it remains effective and helps them maintain a healthy weight. Others may choose to stop treatment once they have achieved and maintained their target weight. In some cases, a lower maintenance dose may be used to support ongoing weight management.

If treatment is stopped, appetite may increase and some people regain weight. For this reason, maintaining healthy eating habits and regular physical activity remains important whether treatment is continued or discontinued.

Your treatment should be reviewed regularly to ensure it remains safe, effective and appropriate for your individual circumstances.

Is there anything else I can do to help lose weight?

GLP-1 medications work best when combined with healthy lifestyle changes.

Helpful strategies include:

• Increasing physical activity
• Monitoring food intake
• Setting realistic goals
• Improving sleep quality
• Managing stress
• Seeking support from healthcare professionals, family, friends or structured weight management programmes

Small, sustainable changes are more likely to lead to long-term success than rapid weight loss approaches.

Can I drink alcohol while taking Mounjaro or Wegovy?

There is no specific restriction on drinking alcohol while taking GLP-1 medications. However, alcohol contains calories and may make weight loss more difficult.

Alcohol can also worsen some side effects, including nausea, indigestion and stomach upset. If you choose to drink alcohol, consider drinking less often and in smaller amounts, as this may reduce side effects and make it easier to achieve your weight loss goals.

What happens if I miss a dose of my GLP-1 injection?

If you miss a dose, follow the instructions provided in the Patient Information Leaflet supplied with your medication.

The advice differs depending on which GLP-1 medicine you are using and how long it has been since the missed dose. Do not take an extra dose to make up for a missed injection.

If you are unsure what to do, contact your medication prescriber for advice.

Will I regain weight if I stop taking GLP-1 medication?

Weight regain can occur after stopping GLP-1 treatment, particularly if healthy eating habits and physical activity are not maintained.

GLP-1 medications help reduce appetite and food intake. When treatment stops, hunger levels may gradually return to previous levels, making it easier to regain weight.

For this reason, GLP-1 medicines should be viewed as part of a long-term weight management plan that includes sustainable lifestyle changes.

How quickly do GLP-1 medications work?

Most people notice a reduction in appetite within the first few weeks of treatment. Weight loss is usually gradual and becomes more noticeable as the dose is increased and treatment continues.

The amount of weight lost varies between individuals and depends on factors such as starting weight, diet, physical activity and adherence to treatment.

Can I exercise while taking GLP-1 medication?

Yes. Regular physical activity is encouraged while using GLP-1 medications.

Combining treatment with exercise and a healthy diet can improve weight loss results and provide additional health benefits, including improved fitness, blood pressure and blood sugar control.

Choose activities that are appropriate for your fitness level and increase activity gradually if needed.

Why am I not losing weight on Mounjaro or Wegovy?

Weight loss results vary from person to person and may not happen at the same rate for everyone.

Possible reasons for slower-than-expected weight loss include:

• Not yet reaching a maintenance dose
• Changes in appetite being less pronounced than expected
• Consuming high-calorie foods or drinks despite eating smaller portions
• Limited physical activity
• Medical conditions that can affect weight, such as an underactive thyroid
• Certain medications that may contribute to weight gain

Weight loss is usually gradual and may become more noticeable as treatment continues. If you are concerned about your progress, speak to your healthcare provider for advice.

Can I switch from Wegovy to Mounjaro?

Some people may switch from Wegovy (semaglutide) to Mounjaro (tirzepatide) if advised by their prescriber.

The two medicines work in slightly different ways and use different dosing schedules. If a switch is appropriate, your prescriber will advise when to stop one treatment and start the other.

Do not switch medications without medical advice, as the timing and starting dose will need to be tailored to your individual circumstances.

What should I do if side effects are affecting my appetite or eating?

A reduced appetite is an expected effect of GLP-1 treatment and helps support weight loss. However, some people may experience nausea, stomach discomfort or other side effects that make eating difficult.

If side effects are affecting your appetite or food intake, it may help to:

• Eat smaller meals more frequently
• Eat slowly and stop when comfortably full
• Choose simple, bland foods if feeling nauseous
• Stay well hydrated
• Avoid large, fatty or very rich meals

Side effects are often most noticeable when starting treatment or after a dose increase and usually improve over time.

If you are struggling to eat or drink adequately, experiencing persistent vomiting, or have concerns about side effects, seek medical advice.

Can I get weight loss treatment on the NHS?

Some weight loss treatments, including GLP-1 medicines such as Mounjaro (tirzepatide) and Wegovy (semaglutide), are available on the NHS. However, access is limited and depends on national and local NHS eligibility criteria.

In general, treatment is offered to people who meet specific requirements based on their BMI, weight-related health conditions and, in some cases, participation in a specialist weight management service. Availability can also vary between different areas of the UK as local NHS services introduce these treatments.

If you think you may be eligible, speak to your GP surgery. They can advise whether you meet the current criteria and what treatment options are available in your area.

If you do not qualify for NHS treatment, or prefer not to wait, private treatment may be an alternative. Our clinicians will assess whether treatment is safe and appropriate for you before prescribing.

Weight loss treatment