• Your Body Mass Index (BMI)

  • What is Body Mass Index (BMI)?

    Body Mass Index (BMI) is a measurement of body fat based on a person's height and weight, used to estimate if they are a healthy weight for their size. 

    A healthy adult BMI typically falls between 18.5 and 24.9, while a score of 25 to 29.9 indicates being overweight, and a BMI of 30 or higher signifies obesity. 

    Our BMI calculator adjusts the calculation for age, sex and ethnic background. However, BMI still has limitations – for example, it can be inaccurate for muscular individuals.

  • cm ft / in

  • kg st / lbs

  • Why are we asking?

  • Why are we asking?

  • According to the standard way of interpreting BMI, you are underweight.

  • According to the standard way of interpreting BMI, you are a healthy weight.

  • According to the standard way of interpreting BMI, your weight is currently unhealthy.

  • According to the standard way of interpreting BMI, you are living with obesity.

  • According to the standard way of interpreting BMI, you are living with severe obesity.

  • To maintain a healthy weight:
     
    NHS inform recommends a balanced diet with plenty of fruit, vegetables, and high-fibre starchy foods, combined with regular physical activity.
     
    Key strategies include:
    • setting realistic goals
    • having planned meals
    • drinking enough fluids
    • choosing lower-fat dairy and unsaturated oils
    • reducing foods high in fat, salt, and sugar.
     
    Keeping active
     
    It’s recommended that all adults should try to be active every day and should complete at least 150 minutes of moderate aerobic exercise per week. This could include many different activities such as cycling, walking or even heavy housework where your breathing is increased but you are still able to talk.
     
    Alternatively, you could complete 75 minutes of vigorous aerobic exercise, which could include activities such as running or a game of football where your breathing is fast and you are finding it difficult to talk during. You could split this up into manageable workouts such as 30 minutes over 5 days of the week.
     
    It’s is also recommended that adults include strength and balance exercises twice a week that keep muscle, bones and joints strong and reduce our risk of frailty and falls in later life. NHS inform recommends some useful strength and balance exercises.
     
     
    Healthy ways to gain weight:

    Gaining weight can be difficult for some people.

    Being underweight could mean you're missing out on vitamins and minerals. 
     
    This could lead to health problems such as a weak immune system and bone fractures.

    NHS UK recommends some tips and changes to help you to gain a healthy weight:
    • gain weight gradually by adding healthy calories – adults could try adding around 300 to 500 extra calories a day
    • eat smaller meals more often, adding healthy snacks between meals 
    • add extra calories to your meals with cheese, nuts, and seeds 
    • have high-calorie drinks in between meals, such as milkshakes 
    • have a balanced diet – choose from a variety of food groups, such as fruit and vegetables, starchy carbohydrates and dairy and alternatives 
    • add protein to your meals with beans, pulses, fish, eggs and lean meat 
    • have snacks that are easy to prepare, such as yogurt or rice pudding 
    • build muscle with strength training or yoga – exercise can also improve your appetite

    To add healthy calories, you could: 

    • try free recipes on Healthier Families 
    • follow the Eatwell Guide to learn more about what makes up a healthy diet 
      Get meals at home (meals on wheels)


    If you struggle to cook or shop for yourself, you may be entitled to have meals delivered to your home. This is provided by your local council's social services. 

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  • Please check with your healthcare professional whether you have any other weight-related conditions or risk factors. Your healthcare professional can use the checklist below to identify any risk factors.

    • Professionals – Co-morbidities (additional risk factors)  

    • Signs of raised intracranial pressure such as vision loss and/or recurrent headaches

    • Apnoeas / hypopnoeas during sleep due to increased upper airway resistance

    • Hyperventilation and / or breathlessness and / or wheezing due to reduced lung or diaphragmatic compliance

    • Reduced Left Ventricular systolic function - Heart Failure with Reduced Ejection Fracture - HFrEF

    • Chronic / recurrent atrial fibrillation

    • Pulmonary artery hypertension

    • Chronic fatigue, lower limb oedema due to impaired diastolic dysfunction - Heart Failure with Preserved Ejection Fracture - HFpEF

    • Recurrent DVT and/or pulmonary thromboembolic disease
      Cardiovascular (arterial),Raised arterial blood pressure

    • The cluster of hypoglycaemia (also prediabetes / type 2 diabetes), high triglyceride levels, and low HDL cholesterol levels

    • NAFLD with hepatic fibrosis

    • Microalbuminuria with reduced eGFR

    • Recurrent / chronic urinary incontinence

    • Anovulation, oligo-menorrhoea and polycystic ovary syndrome (PCOS)

    • Male hypogonadism

    • Chronic, severe knee or hip pain associated with joint stiffness and reduced range of joint motion

    • Lower limb lymphoedema causing chronic pain and/or reduced range of motion

    • Significant, age-adjusted limitation of mobility and/or other basic Activities of Daily Living (ADL= bathing, dressing, toileting, continence, eating)

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    • What is your waist to height ratio?

      Waist to height ratio is an additional measure of excess fat  in adults who have a BMI under 35.

      To calculate your waist to height ratio:

      • Find the middle point between your lowest rib and your hip bone. This should be roughly level with your belly button.
        Wrap the tape measure around this middle point, breathing naturally and not holding your tummy in.
      • Take your measurement and divide it by your height, measured in the same units (for example, centimetres or inches).
      • For example, if your waist is 80cm and you are 160cm tall, you would calculate your result like this: 80 divided by 160, which equals 0.5.
        A waist to height ratio of 0.5 or higher means you may have increased health risks.
  • info icon

    Your healthcare professional will discuss any risks to your health associated with your weight and which weight management options are best for you. See the weight management options below.

  • Options to help you to achieve a healthy weight

    Managing your weight involves some changes in your lifestyle and eating habits. Try the tools in the Getting ready for change section of this toolkit to assess how ready you are to make these changes.

    You may find the following resources and tools helpful:

    • Help with healthy eating and weight management - NHS inform
    • Lose weight - Better Health - NHS UK
    • Download the free NHS UK Weight Loss Plan app. You can find it by searching for "NHS Weight Loss Plan" in the Apple App Store for iOS devices or on Google Play for Android devices. This 12-week programme offers advice and tools to help you start healthier eating habits, become more active, and begin losing weight.
    Download app from Google Play StoreDownload app from Apple App Store

    You can also explore the weight management services available in your area. Choose your NHS Board from the list below. 

  • info icon

    Managing your weight involves some changes in your lifestyle and eating habits. Try these tools to assess how ready you are to make these changes.

  • Options to help you to achieve a healthy weight

    Managing your weight involves some changes in your lifestyle and eating habits. Try the tools in the Getting ready for change section of this toolkit to assess how ready you are to make these changes.

    You may find the following resources and tools helpful:

    • Help with healthy eating and weight management - NHS inform
    • Lose weight - Better Health - NHS UK
    • Download the free NHS UK Weight Loss Plan app. You can find it by searching for "NHS Weight Loss Plan" in the Apple App Store for iOS devices or on Google Play for Android devices. This 12-week programme offers advice and tools to help you start healthier eating habits, become more active, and begin losing weight.
    Download app from Google Play StoreDownload app from Apple App Store

    You can also explore the weight management services available in your area. Choose your NHS Board from the list below. 

  • info icon

    Managing your weight involves some changes in your lifestyle and eating habits. Try these tools to assess how ready you are to make these changes.

  • Weight management options in my NHS Board

  • NHS Ayrshire & Arran

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Borders

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Dumfries & Galloway

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Fife

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Forth Valley

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Weight loss surgery options in my NHS Board

  • NHS Grampian

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Greater Glasgow & Clyde

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Weight loss surgery options in my NHS Board

  • NHS Highland

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Lanarkshire

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Lothian

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Orkney

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Shetland

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Tayside

    Weight management services in my NHS Board

  • Medicines for weight management in my NHS Board

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • NHS Western Isles

    Weight management services in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • Medicines for weight management in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

    Weight loss surgery options in my NHS Board

    Your general practice can provide personalised advice and refer you to appropriate services and support within your health board for weight management.

  • Diet and exercise

    You may find the following resources and tools helpful:

    • Help with healthy eating and weight management - NHS inform
    • Lose weight - Better Health - NHS UK

    Download the free NHS UK Weight Loss Plan app. You can find it by searching for "NHS Weight Loss Plan" in the Apple App Store for iOS devices or on Google Play for Android devices. This 12-week programme offers advice and tools to help you start healthier eating habits, become more active, and begin losing weight.

    Download app from Google Play StoreDownload app from Apple App Store
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