- 1 thin and diagnosis
- 2 Symptoms of thin
- 3 reasons for thin
- 4 Health complications Thinnest
- 5 References
Thin and diagnosis
Body mass index is commonly used to classify the thin (in English: Underweight), as the decline in this indicator of 18.5 indicates that the person is suffering from thin, it is worth mentioning that this indicator is not a tool for diagnosing it is a system of classification used by health organizations and doctors to assess weight, and can also the use of fat in the body to assess its size, where it should be equal measure fat in a woman's body at least 10-13%, while the fat man when measuring more than 2-5% in order to meet the basic functions of the body, it is also recommended for those who believed that suffers from a slim review doctor to determine the cause. 
Symptoms of thin
Can appear on a slim person some symptoms in the body, but some of these symptoms can be associated with other health reasons for, and examples include hands-filled Baerouk which sees some of the signs of infection thinness but bodybuilders also have races phenomenon, and therefore, some of the symptoms It can be associated with thinness after making sure they are not caused by other reasons, including: 
- Irregular menstrual cycle or the difficulty of pregnancy.
- Easy to break bones.
- Hair loss.
- A weakened immune system.
- Feeling of dizziness, fatigue due to blood (anemia in English: Anemia).
Reasons for thin
There are many reasons associated with weight loss and slim, and sometimes causes so subtle, and the most important reasons for thin as follows: 
- Family history: Some people have been suffering from low body mass index naturally, because of some physical properties inherited from the family.
- Physical diseases: where can some diseases lead to difficulty gaining weight, which is usually caused by diarrhea, vomiting, nausea, as can reduce appetite in other cases, which leads to a lack of eating, and these diseases; Diabetes, cancer, thyroid disease, and digestive disorders; Such as Crohn's (English disease: Crohn's disease), ulcerative colitis (in English: Ulcerative colitis).
- Mental illness: it can be poor mental health affects the ability to eat, appetite, body image, and situations that can affect the weight; Depression, anxiety, and obsessive-compulsive disorder (in English: Obsessive-compulsive disorder) and eating disorders (in English: Eating disorder) Kalshrh nervosa (in English: Bulimia).
- High metabolic rate: some people suffering from high metabolic rate, and therefore even when eating high-energy food, it can not cause weight gain significantly.
- Frequent physical activity: it can athletes or people who have high levels of exercise to burn their body high amounts of calories, which leads to the loss of body weight.
Health complications Thinnest
There are some health risks that result from thin or poor nutrition, and these risks as follows: 
- Malnutrition can not consume a person who suffers from thin enough of the nutrients needed by the body, which may cause malnutrition (in English: Malnutrition), which in turn may affect the health, and the person can be more susceptible to this case if the thin due to a non-balanced diet or because of the disease affects the absorption of nutrients in the body, it should be noted that malnutrition can cause some vitamin deficiency in the body, or anemia.
- Increased risk of complications from surgery: where one study found that people who suffer from thin and underwent surgery in full knee replacement (in English: Total knee replacement surgery) were more susceptible to infection after surgery compared with others, and despite the inability of researchers to identify the reason behind therefore, they believe that the bodies of infected thinness is not able to heal the wounds, as is the case for people who have a normal body mass index, it has also found that the thin they had a lower level of hemoglobin before surgery.
- Osteoporosis: where can cause low weight and increased risk of low bone mineral density (in English: Bone mineral density), osteoporosis (in English: Osteoporosis).
- Infertility: the risk of interruption of menstruation increases (in English: Amenorrhea) women who possess a low body mass index, as well as the risk of increasing the incidence of various menstrual disorders, and irregular menstruation, or absence can be an indicator of ovulation interruption (in English: Anovulation) In case this was a chronic condition, they lead to infertility (in English: infertility), so the woman who suffers from thin and want to pregnancy recommend reviewing your doctor to make sure that the process of ovulation regularly has, and can advising them the doctor to increase weight before pregnancy, as thin during pregnancy It may be hazardous to the child.
- Growth retardation: Where can children with thinness missing some nutrients due to malnutrition and absorption, which can affect the brain development have, and a delay in the growth phase, where the brain needs of various nutrients to grow properly, usually watching the pediatrician a child's growth , to see the changes that have taken place, and if the low rate of growth of the child, it can warn that the child does not gain weight at the expected rate.
- Reduced immunity: One recent study has indicated that there is a relationship between infection and thin, and it was difficult to determine whether this is due to thin, or as a result of hidden causes that cause them.
- ^ أ ب Malia Frey (7-6-2018), "Signs That You Are Underweight"، www.verywellfit.com, Retrieved 23-9-2018. Edited.
- ↑ Rachel Nall (24-4-2018), "What are the risks of being underweight?"، www.medicalnewstoday.com, Retrieved 23-9-2018. Edited.
- ↑ Janna Young (17-4-2017), "6 Health Risks of Being Underweight"، www.healthline.com, Retrieved 23-9-2018. Edited.
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