Expert Guide on Identifying Eating Disorders & Time to Take Action

By Harriet Frew

Harriet Frew, an Eating Disorder Therapist and trainer in eating disorders and body image, promotes a healthy relationship with food and your body.

Women Fitness Team got in touch with her to gain answers to questions frequently asked on eating disorders- link to BMI, identifying signs and seeking guidance. We hope they serve you well.


 Anorexia nervosa, bulimia nervosa and binge-eating disorder are the three main eating disorders. Can you highlight a generic difference between the three and its relation with BMI?

An eating disorder is a serious mental health condition which describes behaviour that focuses on an individual’s abnormal relationship with food and is usually accompanied by a strong desire to change weight and body shape. Self worth has become disproportionately valued around ability to control weight and shape and restrict food intake.

  • Anorexia nervosa is an eating disorder, characterised by a strong desire to lose weight. This is achieved by strictly limiting food intake or through excessive exercise. People with anorexia may also use purging after eating using vomiting or laxatives (purging sub-type). 
  • Bulimia nervosa is an eating disorder, in which people often strive to control or restrict their food intake to manage weight. However, the strict control is often unsustainable, and this is commonly followed by bingeing (eating quickly, large quantities of food in a discrete period of time, usually in secret). People with bulimia feel much shame and guilt for these eating episodes and then compensate for the bingeing through “purging” with vomiting or using laxatives, over-exercise or further food restriction. People with bulimia are often close to normal weight, though they typically have a distorted body image, and their weight may fluctuate regularly. 
  • Binge eating disorder is more common than the other eating disorders and more evenly distributed between men and women, most of whom are mature adults.

Again, binge eaters aim to eat a restrictive diet which is often unsustainable, and this is commonly followed by bingeing (eating quickly, large quantities of food in a discrete period of time, usually in secret). This behaviour usually involves a great deal of shame and anguish. Someone with binge eating disorder does not purge and can experience intense weight fluctuations.

BMI Range With Eating Disorders

  • Below BMI 17.5 = anorexia nervosa 
  • BMI 15 – 17.5 – moderate anorexia nervosa
  • BMI 13.5- 15 – severe anorexia nervosa
  • BMI 13.5 and below – critical anorexia nervosa – hospital admission likely needed
  • Someone with a BMI of 17.5 and below and purging through vomiting meets diagnosis of anorexia nervosa (purging sub-type).
  • Someone with BMI of over 17.5 and purging through vomiting meets diagnosis of bulimia nervosa.
  • With bulimia and binge eating, BMI can be anything from over 17.5 to any limit. These eating disorders are hidden and can impact people of any weight and shape.

How can a teenager or woman identify the early signals that they have an eating disorder?

Signs and symptoms of anorexia: –

  • loss of periods (for women)
  • loss of sex drive
  • tiredness; poor concentration
  • feeling cold
  • lanugo (fine hair covering the body)
  • dizziness
  • poor quality hair and nails
  • risk of osteoporosis
  • damage to the liver, kidneys, heart and digestive system

Someone with anorexia may also develop certain behaviours and show particular attitudes to keep their eating disorder secret. Typical examples include:

  • avoiding eating in public
  • eating tiny amounts of very specific foods, rather than a normal range of food types
  • complaining of being full when they have hardly eaten at all
  • becoming very focused on body shape and size
  • denying that they are less than a reasonable weight and need any help
  • finding the idea of gaining weight extremely disturbing.

People with bulimia will often try to hide their illness, but will identify with some of the following signs and symptoms: –

  • eating swinging between controlled and uncontrolled over-eating
  • over-exercising
  • taking laxatives
  • vomiting; visiting the toilet very soon after eating
  • complaining of tiredness
  • marks on hands from being pushed into throat to start gagging reflex
  • weight fluctuations
  • mood swings.

People with binge eating disorder will often try to hide their illness, but you may identify some of the following signs and symptoms: –

  • eating swinging between controlled and uncontrolled over-eating
  • over-exercising
  • complaining of tiredness and showing mood swings
  • weight fluctuations
  • mood swings

When is the right time to accept and reach out for help from a health expert to take control over disordered eating.

If symptoms are impacting daily life and wellbeing. For example: physical effects such as lack of energy or poor concentration; physical impacts of weight loss, purging or binge eating; social impacts such as isolation or avoiding social events with friends due to rigid routines and anxiety around food; emotional impacts such as low mood, high anxiety and preoccupation with food.


How far is lifestyle & stress responsible for one’s body weight?

Stress can definitely impact weight in either direction through restrictive eating or overeating. Acute stress often causes the fight/flight response with adrenaline release and may result in loss of appetite. Chronic stress tends to be more often linked to overeating/emotional eating through increased cortisol production.

Good self-care through lifestyle is likely to help people sustain a healthier weight. This can include: eating regularly and a balanced diet; getting good sleep; managing alcohol; taking exercise; having good relationships and a purpose.

As an eating disorder therapist please share your piece of advice for people suffering with eating disorders & family to help an individual overcome it. 

  • If you think you might have an eating disorder, contact your GP to get referred for specialist help. Seeking help early is preferable before and eating disorder becomes an entrenched habit.
  • Contact BEAT (Eating Disorders Charity) for more information.
  • Most NHS services will offer family support too.
  • Recommended book: Skills-based Caring for a Loved One with an Eating Disorder by Janet Treasure (South London and Maudsley Hospital and Professor at Kings College London, UK)

How significant is the role of BMI in health evaluation.

BMI definitely has its limitations when looking at individuals. For example: someone with a high muscle body composition or very tall, or larger boned may appear to have an overweight BMI, which does not reflect their overall health.

BMI can also be limiting between different cultural groups. For example: Asian people may have lower BMIs naturally for genetic reasons and having a smaller body frame.

BMI does offer a guide to understanding body size in populations and has some generic value. It definitely needs approaching with caution and to look at the individual circumstance.


BIO – Ms. Harriet Frew is an experienced counsellor specialising in eating disorders and body image. She has worked in an NHS Adult Eating Disorder Service and private practice since 2003.  Has personal experience of bulimia nervosa and have been fully recovered for many years. She’s passionate about eating disorders and enjoys writing, filming and creating information through my podcast and social media, to help and support others.


The Content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

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