Being consistently underweight can cause long term health problems, will affect all your body systems including your physical, psychological and social functioning and even change the way you are as a person.

Some of the effects described here are direct effects of sustained under-eating rather than a low weight and can affect anyone who is markedly under-eating regardless of their weight.



  • –  Your brain needs a lot of energy to function properly so without adequate energy your thinking will become rigid and inflexible and you are unable to switch easily between subjects.
  • –  Making decisions also becomes difficult and concentration is almost always affected.
  • –  Because you are under-eating, physiological and psychological pressure builds up and a pre-occupation with food and eating (not-eating), starts to crowd out other areas of your life.
  • –  You might give up hobbies and interests and stop seeing and meeting up with friends.
  • –  Your thoughts will tend to turn inward and you will have a need for more routine and predictability,you will become less able to be spontaneous.(If your thinking changes; you will be the least likely person to notice these changes)


– Your mood will be lowered and you may find that you become easily irritated or upset and seek to isolate yourself from friends and family.


  • –  People who have been significantly underweight for a long time change the way they behave. They might think that this is just the way they are, but many of these effects like low mood, irritability and isolating yourself are due to being underweight.
  • –  Obsessional behaviour can also be seen in ritualised eating routines; often eating is only done in secret or in a particular way.
  • –  You will be prone to setting rigid rules around what you must not eat or must not do.

– Obsessional behaviour might be also be seen in terms of a need to be clean and tidy or even hoarding.


There are a number of effects on your health which of course will depend on the extent and duration of your under-eating.

Heart and Circulation

– Heart muscle is lost, blood pressure and pulse drop. There is a risk of heart beat irregularities.

Sex Hormones and Fertility

  • –  Hormonal function is affected as all non-essential processes are stopped to preserve energy.
  • –  Cessation of menstrual periods may result in infertility.
  • –  A loss of sex drive is experienced and responsiveness is affected.Bones, muscles and joints

– There is a reduction in bone strength and an increased risk of osteoporosis and fractures. The Muscles weaken and joints become swollen

Mouth and Throat

-The throat becomes sore and irritated,
– The Oesophagus can tear and rupture. Reflux is also much more likely
– The mouth often develops ulcers and the tooth enamel decays along with more cavities

Intestinal Function

  • –  The gut slows right down as the body attempts to exact energy from the limited food sources.
  • –  Food in the stomach takes much longer than usual to pass into the small intestine which is why anuncomfortable sensation of fullness is experienced even after eating very little.
  • –  Taste may be affected and you may feel persistent gnawing hunger as your body and mind compelyou to eat.Heart
  • –  Low blood pressure, Slower heart rate, Palpitations/ irregular heartbeatMuscles

– Your muscles will waste and weakness could result; especially noticeable when walking upstairs or attempting to get up from a sitting or squatting position.

Skin and Hair

  • –  A downy hair covering can start to grow on the face, forearms, back and abdomen.
  • –  You may lose hair from your scalp.
  • –  Often skin becomes dry and may have an orange hue.Temperature regulation

– People often feel profoundly cold due to a reduction in body temperature.


– Sleep tends to be less refreshing and you may wake early.


Some of the difficulties that you are having right now may be a direct effect of under-eating and having an unhealthy low weight.

Some of the effects of being under-weight will keep you ‘locked in’ to your eating disorder.

Your personality is affected by being markedly under-weight, the real you will return once you have reached a healthy weight.

Some of these effects are dangerous and can cause long-term damage to your body.

It is not easy to get back on track once an eating order takes hold and requires real effort and application to regain a healthy mind-set. However, if you regain weight to a low, but healthy level, the majority of these symptoms will go away.

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