Keeping a healthy weight

Body Mass Index (BMI)

Doctors use a measure called BMI as a guide to whether someone is a healthy weight for their height. It isn’t perfect, but it is a good guide for most people.

It’s calculated by dividing your weight in kilograms by the square of your height in metres. 

Click here to visit the NHS’s online BMI calculator.

The risk of developing a condition such as non-alcohol related fatty liver disease, type 2 diabetes, or heart and circulatory disease is higher for people with a weight in the overweight or obese ranges.

For people who are Black, Asian or belong to another ethnic minority group the risk of type 2 diabetes and other long-term conditions starts to increase at a BMI of 23. Even though this is in the healthy range it is a good idea to keep an eye on your weight if your BMI is 23 or more.

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Waist size

Where you carry weight can make a difference too. People with an apple body shape who carry their weight around their tummy have a higher risk of health problems than people with a pear shape.

Having too much tummy fat can increase the risk of conditions such as type 2 diabetes, heart disease and stroke even if you have a healthy BMI.

You can check if you’re carrying too much fat around your tummy by measuring your waist. Your waist measurement isn’t the same as your clothes size – but it’s easy to measure.

• Get a tape measure and adjust your clothes so you are not measuring over them.
• Find the bottom of your rib bones and the top of your hip bone. Your waist is midway between these points.
• Wrap the measuring tape all the way around your waist.
• Breathe out naturally and then take the measurement.

Try to lose weight if your waist is:

• 94cm (37ins) or more for men
• 80cm (31.5ins) or more for women

You’re risk of developing a health condition is very high and you should speak to your GP if your waist is:

• 102cm (40ins) or more for men
• 88cm (34ins) or more for women

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Energy balance, calories and weight

To reach and stay at a healthy weight you need to balance the energy you get from your food and drinks with the energy you use.

Energy is measured in calories. If you take in fewer calories than your body uses you will lose weight. And if you take in more calories than you use you will put on weight.

The amount of energy your body needs is affected by:

• whether you are a man or a woman
• how old you are
• how much you weigh and how muscular you are
• how physically active you are

As a rule of thumb a healthy man uses about 2,500 calories a day. And a healthy woman uses about 2,000 calories a day.

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Lose weight sensibly – making small changes

For most people it is healthier to lose weight steadily over time. To lose weight you need to use more calories than you take in.

There are 2 ways to do this. Eat a healthy, balanced diet and be more physically active. Losing weight this way is best done steadily. Aim to lose 2 pounds (1 kg) a week at the most.

They are big changes and it can feel overwhelming. But you don’t have to make them all in one go. You can break them both down into small changes that build up over time. Don’t put pressure on yourself to be perfect. Think about how far you’ve come, take it one step at a time and keep going.

There are lots of small ways to start losing weight. The best tips are the ones that work for you and you can stick with. Be realistic and make one or two changes at a time. Once they have become part of your normal life, add another small change.

Read our pages about eating a well-balanced diet and about physical activity and exercise for more information and ideas of small changes you can try.

For information and tips to help you keep your weight healthy download our Treating MASLD with a healthy diet and physical activity booklet.

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What is a very low calorie diet?

A very low calorie diet has no more than 800 calories a day. It should be clinically supervised to make sure you are still getting all the vitamins, minerals and other nutrients your body needs (a nutritionally complete diet). You might also need regular checks to see if you need to change the dose of any medicines you take.

There is some evidence these diets can be used to treat metabolic disease (including MASLD). Talk to your doctor before starting a diet with a very low calorie intake or that cuts out certain types of food altogether to check that it would be a suitable and safe option for you.

If you are struggling to lose weight ask about referral to a dedicated weight management service. They have access to more specialist treatments that may include very low calorie diets or weight-loss medicines or surgery (bariatric surgery).

The treatment they recommend will take into account your BMI and whether you have any other conditions, such as type 2 diabetes, high blood pressure or high cholesterol.

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Further support

If you are struggling to lose weight, or would need to lose a lot of weight to get to a healthy BMI, speak to your doctor. They could refer you to a local weight loss programme, or to a dedicated weight management service if needed.

People with liver disease can also be at risk of being underweight. This is more common among people who have been diagnosed with cirrhosis or who are experiencing eating difficulties such as loss of appetite or feeling sick (nausea). You might need to change what and how you eat to make sure you get the nourishment your body needs. Speak to your doctor or dietitian for advice on how to increase your calories and protein intake. You can also read our advice on diet for people with cirrhosis and coping with eating difficulties.

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