Due to the worldwide obesity epidemic, there has been a large emphasis placed on weight loss and the health consequences of holding excess weight. However, what about being underweight? This issue tends to get looked over yet the consequences can be just as alarming as those of obesity.
Being underweight can be experienced by anyone, not just those who suffer from eating disorders. It may be as a result of undergoing a medical treatment, it could be due to a condition like hyperthyroidism or you may be someone who just doesn’t eat much.
Health consequences
So how exactly can being underweight effect our health in the short and long- term? Of course the severity of underweight will make a big difference to the health repercussions experienced but I will discuss all of the possible impacts below.
Immune system
Often people are underweight due to an insufficient intake of energy (kilojoules/calories). Frequently eating under your requirements will generally provide inadequate nutrition as well – this will lead to an individual becoming malnourished. With improper nutrients, your body struggles to fend off infections and illness, making you more prone to them and general poor health. For instance, zinc helps with wound healing.
Hormonal changes
Individuals who are underweight can suffer from hormonal changes. Such alterations can include:
- Decreased reproductive hormones (oestrogen, dehydroepiandrosterone (DHEA)): These hormones are important for bone and heart health, amongst maintaining other bodily functions. A decrease in reproductive hormones often leads to irregular or lacking menstruation, known as amenorrhoea. If left unresolved, it can lead to infertility and loss of bone density.
- Decreased growth hormones: Children and teens that are underweight may experience retardation in their growth.
- Increase in stress hormones.
- Decrease in thyroid hormones.
Pregnancy
Women who are considerably underweight when they fall pregnant are at an increased risk of miscarriage and having a baby of low birth weight or with defects.
Cardiovascular
People who are severely underweight are at risk of developing heart arrhythmias. Your heart is a muscle and when the body is deprived of energy, the muscle starves and hence is depleted (size decreases) and weakened. This can result in bradycardia – an irregularly slow heart beat. Blood pressure and blood flow can also drop.
These complications can occur from an imbalance of minerals due to starvation and dehydration. Such minerals include potassium, calcium, phosphate and magnesium. These minerals are essential for maintaining a normal heartbeat and if they are not replaced, serious consequences can result.
Bone health
Those who are underweight are at a greater risk of osteopenia (bone calcium loss) and osteoporosis (loss of bone density). This has particularly detrimental effects to children and adolescents who fail to develop strong bones during their development. This often results in a stunting of growth and places them at a high risk of developing complications later in life.
Bone density losses worsen the more underweight a person becomes. For underweight women, achieving regular menstruation (if amenorrhoea is experienced) is crucial to regaining bone density due to oestrogens role in bone health. For young males, a decline in testosterone can result in loss of bone density and gaining weight can result in some catch up growth.
Gastrointestinal
Constipation and bloating is a common issue if inadequate food is consumed or the wrong types of food, e.g. not enough fibre providing foods. The gut also slows down which means the food moves through at a slower rate. This can contribute to a feeling of fullness after having eaten only a small amount.
Nutrient deficiencies
Nutrient deficiencies can also result if not enough food is consumed or not enough variety. A common one is iron deficiency anaemia.
Neurological
Your brain runs on energy and if you don’t frequently refuel it, it suffers. Not consuming enough energy via food and quality carbohydrates will leave you with poor concentration and often feeling fatigued.
Other presentations
- Low muscle mass
- Hair loss
- Fine hair (lanugo) growing on skin – mainly face, arms, back and abdomen
- Skin can become dry and sometimes discoloured
- Often feeling cold due to an inability to properly regulate temperature
- Disrupted sleep
Contact us for results focused nutritional advice
This article was written by our dietitian Belinda Elwin who is a Dietitians Association of Australia member and Accredited Practising Dietitian and Nutritionist. If you have questions about the health effects of being underweight or other nutrition related issues, make an appointment. We‘ll provide you with a simple and effective routine targeted to your concerns. Contact us today.
