Hi there, today’s post is about how being underweight can affect health.

Maybe you are reading this blog because you identify as being underweight or know someone who is. For many, it’s not a choice and gaining weight is quite difficult for different reasons.

Before we get into the subject of risks that can come about from being seriously underweight, let’s just take a step back to understand who is considered underweight, as well as some of the possible causes.

                                 How Do I Know If I’m Underweight?

The answer to this doesn’t lie in family, friends or even strangers telling you how skinny you are, or how you should eat more. (Eye roll).

Naturally, hearing that regularly will carry some weight with most people, however there are more scientific ways to figure this out

In fact, weight status is generally measured by an international standard called the BMI system.

BMI is worked out by a person’s weight divided by their height. This number falls into one of four categories as shown below.

BMI Ranges
Underweight: Under 18.5
Healthy weight range: 18.5-24.9
Overweight: 25-29.9
Obese: 30 or higher.

On the whole, the BMI system is an approximate measure of body fat.  

For example as an adult, my Body Mass Index (BMI) fell under 18 for many years which comes under the category of being underweight.

Now, the BMI system isn’t perfect and doesn’t consider things like bone density, genetics, muscle mass, gender etc.

So there are criticisms of this system, however by and large, this is the standard used especially by health professionals to work out weight status.

You can use any BMI calculator to work out where you fall in the categories if you know your height and current weight. Check your BMI here

If you do fall under the 18.5 number, I encourage you to go speak to your doctor about your weight, and I’ve explained why here.

                                           Causes Of Being Underweight:

So here is a list of some causes of being underweight.

• Genetics
• Diseases and chronic illness like cancer.
• Malabsorption -where the body can’t properly absorb nutrients from food.
• Poverty, homelessness, pandemics, wars etc.
• A naturally high metabolism
• Low appetite and/or high satiety cues (feeling full very easily)
• Poor eating habits e.g. being too busy or forgetting to eat (Yes, for real, though this is definitely not me.)
• Addictions
• Eating disorders e.g. anorexia and other mental health issues like depression etc.
• Being highly active in intense physical activities or sports that just torch calories
• Age. (Many seniors aged 65+ fall into the underweight category)

Of course, this isn’t an exhaustive list and I’m sure there are other reasons as well.

Just going slightly off tangent for a second, when I was researching this post I found out something interestingly weird.

Did you know the average weight of a professional jockey is usually between 49 – 54kgs? (Approximately 110-125 lbs)

And most jockeys are men!

Hmmmm.

Anyway, going back to the focus of this post. 

It is important to know how being underweight can affect your health. And more so, being severely underweight can bring about serious health risks.

Now I just want to clarify that not everyone who is underweight has or will have health issues.

Many are following a balanced diet and giving their bodies the nutrition needed. However due to factors like family history, they may still fall in the underweight category.

On the other hand, did you know when the body doesn’t get the calories and nutrients it needs to function, it starts to break down its own tissue? Read more on this here.

This becomes quite serious when undernutrition continues for long periods of time.

                        How Being Underweight Can Affect Your Health

Low energy and fatigue.

Undernutrition may result in constant tiredness. In the long run, this can affect health, work and/or study, and relationships.

Poor bone health and osteoporosis later in life.

Some studies show being underweight, particularly for women, can increase the risk for osteoporosis in later life.

Irregular periods for women.

Women may not get regular periods if severely underweight and this could lead to infertility.

Poor immunity and falling sick regularly.

Apart from feeling run down, a person may fall sick constantly, and also take much longer to recover from common illnesses like coughs and colds.

Malnutrition and anaemia.

These can bring about general weakness and the reduced ability of the body to cope with stress and infections.

Emotional and mental health effects.

These can include anxiety, mood swings and irritability among others.

Developmental delay.

In children, this could mean delays with development including cognition and motor skills, poor immunity and limited growth among others.

Overall poor general form.

The person’s physical appearance may be unhealthy- including a frail body, dry dull skin, hair loss, loose teeth and gum disease etc.

In summary, it sounds like some scary stuff. Now, some of these effects may be generally relevant to underweight people (e.g. immunity, tiredness) but a lot are more related to those who are severely underweight.

Again, I just want to repeat that not everyone who falls into the underweight category will have health issues.  

I’ve written before that I personally had poor immunity to common infections such as colds, coughs and flus from being underweight.

But by ramping up overall on healthy nutrients with a focus on fruits and vegetables, that all changed in a huge way. See this for ideas of what to eat for immunity.

And let’s not forget the other good stuff like exercise, good sleep etc.

But just as an example the last time I got sick with an everyday infection (a cold) was in April 2019 and it’s now almost the end of 2020.

Please be mindful that I’m not a doctor and it is based on my personal experience, however science strongly supports the link between good nutrition and immunity.

So look after yourselves.

And now, in the words of Bugs Bunny, “That’s all folks”