Many of us know the health risks associated with being overweight or obese – but we’re not always aware of how dangerous it can be to be underweight.
Being too thin is worse for your health than being slightly overweight, and there are a number of complications associated with having a BMI of under 18.5 (the official definition of “underweight”).
For many people being underweight means their bones aren’t as strong as they could be and they have fewer ‘reserves’ if they fall ill. It can also affect a woman’s fertility.
– BBC health
Here are seven health problems which can be caused by being underweight:
1. Weak immune system
If you’re underweight, you’re probably not taking in enough nutrients. This affects your body’s immune system, making it more likely that you’ll catch a cold, flu, or whatever else is going around.
2. Low muscle mass
Particularly when being underweight is caused by illness or deliberate food restriction, people who are thin are likely to have a low muscle mass. In teenagers in particular, who are still growing, being underweight can mean that muscles don’t develop well.
3. Hair loss
Being underweight affects your hair – often meaning that you lose hair from your head. You may also end up growing body hair in odd places (especially if you’re female) if you’re too thin. Your hair, just like your body, needs to be nourished by adequate food intake.
Also known as “brittle bones”, osteoporosis makes fractures much more likely. This can be an especial danger if you’re underweight because you do a lot of sport and don’t take in enough energy. Women who have passed the menopause are at especial risk of osteoporosis.
Anemia occurs when the body cannot transport enough oxygen around in red blood cells. It’s often caused by iron deficiencies – not uncommon in women, especially those who are dieting or restricting food intake. Anaemia can make you feel exhausted and can cause heart palpitations and dizziness or fainting.
6. Menstrual irregularities
If you’re female, your periods can become irregular or stop altogether (known as amenorrhea) when you’re underweight. This is because your body thinks you’re starving – if you’re not taking in enough food to stay at a healthy weight, your body definitely doesn’t want to be giving what little energy you have to a baby.
7. Pregnancy complications (or unable to get pregnant)
Even if your periods don’t stop, you’ll have trouble conceiving if you’re underweight. And it can be extremely dangerous for the growing embryo if the mother is too thin: a study by the London School of Hygiene and Tropical Medicine found that:
Women who are very underweight before they become pregnant are 72% more likely to miscarry in the first three months of pregnancy.
Are You Underweight?
If your BMI is under 18.5 (you can find your BMI here), you’re underweight. Even if your BMI is between 18.5 and 20, you are thin for your height and could suffer from some of the problems above.
Your doctor will be able to help if you are experiencing symptoms that you think might be caused by being underweight – please get the advice of a medical professional if you’re at all concerned.