The concept of malnutrition has been almost irrevocably linked to poverty and famine. Fed by a diet of charity commercials and solemn-faced news coverage, most Australians hear ‘malnutrition’ and picture a montage of emaciated children.
The truth? Malnutrition might be more noticeable in developing countries, but it happens right here in Australia too. Research paints an alarming picture: up to 40% of Australian hospital patients and 50% of aged care residents are malnourished [1, 2].
Malnutrition isn’t just a condition that affects people with low body weight, either – overweight and obese people are also at risk. Societal attitudes encourage us to think of having excess weight as bad, and losing that weight as good.
So when overweight people enter situations that put them at risk of malnutrition – like hospitals, aged care and diagnoses of chronic disease – they often hesitate mentioning sudden diet or weight loss to clinicians, because they’ve been conditioned to regard both as positive outcomes.
Unfortunately, failing to take action at the early stages of malnutrition can result in serious consequences, eventuating in a downward spiral of ill health.
In this article, we’re going to examine what malnutrition is, find out why even obese people can be malnourished and bust the myth that all weight loss is good. Keep reading to find out how to make sure your loved ones or patients stay properly nourished.
What is malnutrition?
Malnutrition is an imbalance of energy, protein, vitamins and minerals that causes adverse effects on body shape, bodily function and clinical outcomes .
It can refer to an excess or deficit of macronutrients (carbohydrates, proteins, fats) or micronutrients (vitamins and minerals). Typically, when people say ‘malnutrition’, they’re referring to protein-energy undernutrition, which we’ll talk about more in a minute.
Malnutrition can cause a variety of negative consequences, including slower wound healing, muscle loss, weakened immune systems and a higher rate of mortality.
A good way to define overnutrition is “a form of malnutrition (imbalanced nutrition) arising from excessive intake of nutrients, leading to accumulation of body fat that impairs health (i.e., overweight/obesity)” .
In layman’s terms, overnutrition is when you eat more calories than your body needs; this excess energy is then converted into fat. Signs and symptoms include :
- Excess body fat
- Being overweight
- Excess sweating
- Back and joint pain
- Reduced ability to participate in exercise
Undernutrition (also known as protein-energy malnutrition) is the opposite of overnutrition, occurring when you don’t eat enough protein and energy to meet your body’s needs. This normally means your energy expenditure exceeds the energy you’ve gained from eating food.
Signs and symptoms of undernutrition include :
- General loss of appetite
- Early satiety
- Losing muscle
- Unexplained or unintentional weight loss
- Fatigue, tiredness, loss of energy, confusion and poor concentration
- Reduced ability to perform normal tasks
- Reduced physical performance
- Displaying altered mood states, like lethargy, irritability, apathy (a lack of interest and motivation) or depression
- Wounds heal more slowly
- Skin tears more easily
Signs and symptoms of severe undernutrition :
- Muscle tissue begins to waste away
- Bones start to protrude
- Eyes and cheeks appear sunken
- Skin and hair are dry and brittle
- Feeling cold
- A weakened immune system, which might manifest in infections
As we move through the rest of this article, ‘undernutrition’ will be synonymous with ‘malnutrition’. All references to ‘malnutrition’ mean we’re talking about undernutrition, unless otherwise specified.
Causes of malnutrition
Malnutrition is a complex condition caused by a variety of different factors. Some common causes of malnutrition include:
- Inadequate dietary intake
- Oral dysphagia and impaired swallowing
- Malabsorption conditions and syndromes
- Cognitive decline and dementia
- Medical conditions that increase energy expenditure, like cancer
You can learn about the risk factors for malnutrition here.
Effects of malnutrition
Malnutrition can cause a wide range of problems, even for people who may not look underweight. A lack of proper nutritional intake weakens our bodies, reducing healing rates and making them more susceptible to infections and external trauma.
Some of the most common effects of malnutrition include :
- Reduced wound healing
- Weakened immune systems
- Increased risk of falls and fractures
- Increased chance of pressure sores
- Prolonged and recurrent hospital admissions
- Higher mortality
Together, these conditions can contribute towards ‘a spiral of ill health’, where a person’s health declines exponentially due to a cumulation of factors. Read more about the impacts of the spiral here.
Obesity in Australia
Before we go any further, it’s important we appreciate how widespread obesity is in Australia.
Here are a few key statistics from the Australian Institute of Health and Welfare’s report on obesity .
- 2 in 3 adult Australians are overweight or obese
- 36% of adult Australians are overweight, while 31% are obese
- 41% of adults aged 65-74 are obese
A separate 2020 study found that 30% of Australian hospital inpatients are overweight and that 32% are obese . An estimated 40% of inpatients are malnourished, so it’s inevitable that a percentage of the total inpatient population will be both overweight/obese and malnourished.
With the majority of Australia’s general and inpatient populations overweight or obese, it’s essential that both clinicians and family members understand that malnutrition can affect people with excess weight. Just because someone has a high BMI (Body Mass Index) doesn’t mean they’re nutritionally healthy – malnutrition can affect anyone, even people who aren’t showing visible signs or symptoms.
The myth of healthy weight loss
As a society, we’ve educated ourselves about the dangers of overnutrition. We know how detrimental being obese is to our health, and we’ve created a culture that rewards fitness and weight loss.
Unfortunately, it’s this same mentality that puts overweight and obese people at greater risk of malnutrition. We’ve been conditioned to think that losing excess fat is a positive thing – and it is, as long as it occurs in the right way and under the right circumstances.
But weight loss from reduced appetite, extreme fasting or severely restricted diets is almost never healthy, particularly when it occurs due to age, hospitalisation or any of the other risk factors we discussed earlier. Not absorbing the correct amount of nutrients to offset expenditure is unhealthy for anyone, including people in larger bodies.
Overweight or obese individuals often don’t show obvious symptoms of malnutrition immediately. Unlike underweight or healthy individuals, their excess body fat can mask slight muscle loss, creating the illusion of good nutrition or overnutrition. This can result in health care professionals, friends or family failing to recognise that their patient or loved one is, in fact, malnourished .
For example, a 2016 Italian study found that roughly 10% of obese and overweight hospitalised patients were undernourished; in obese and overweight gastroenterological patients, who can often have trouble eating or absorbing enough nutrients, the risk of malnutrition climbed to over 30% .
In another, more comprehensive study, a team of dietitians analysed over 6,000 critically ill adult patients, of which 31% were overweight, 23% were obese and 5% were severely obese. Of those overweight and obese patients, up to 60% were found to be malnourished . There isn’t a lot of data about the intersection of obesity and malnutrition, but the studies that do exist, like the two we just talked about, are useful because they highlight how easily malnutrition in obese inpatients can be overlooked by both clinicians and families.
While malnutrition in young to middle-aged adults generally has few long-lasting effects, it can, in the short term, cause “higher infection and complication rates, increased muscle loss, impaired wound healing, longer length of hospital stay and increased morbidity and mortality” [7, 8]. That’s why it’s so important that even overweight or obese people are screened for malnutrition – they might not appear malnourished, but their bodies are still vulnerable to the effects of malnutrition.
Older overweight and obese people are also particularly at risk of malnutrition. Remember that Italian study we talked about? They found that up to 80% of obese patients aged 65+ years were at risk of malnutrition, compared to 30% of younger patients . This is because age can cause problems like reduced functional capacity, poor dental health, polypharmacy (taking lots of medication), swallowing problems and reduced senses of smell and taste, which, in turn, makes eating properly harder . Older people are also often affected by sarcopenia, which can make recovering from malnutrition harder than it is for younger people.
If you’re not sure what sarcopenia is, here’s a quick definition: “Sarcopenia is defined as the loss of skeletal muscle mass and quality, which accelerates with aging and is associated with functional decline” . It’s a naturally occurring but preventable state which afflicts most of us as we get older .
Sarcopenic obesity occurs when a clinically obese person is also affected by sarcopenia, which actually magnifies the effects of carrying too much weight . Although sarcopenia isn’t necessarily caused by malnutrition, both share a contributing factor: imbalanced nutritional intake. Even mild malnutrition can worsen the effects of sarcopenia – research has shown that nutritional interventions (like high-protein diets), combined with resistance exercises, can slow or even stop sarcopenia [15, 17].
People with sarcopenic obesity are at even greater risk of health complications than people with just obesity or just sarcopenia. They will often have significantly reduced physical functioning and a higher risk of mobility disability, mortality, cardiovascular disease and Type 2 diabetes [16, 18].
If they do become malnourished, sarcopenia makes it harder for them to regain lost muscle. Younger individuals (aged under 65 years) typically don’t have trouble recovering from the effects of malnutrition, but sarcopenic adults, especially those with sarcopenic obesity, are fighting an uphill battle when it comes to regaining body mass stripped away by malnutrition. This, in turn, can leave them weakened and more vulnerable to other serious health conditions.
The takeaway? Older Australians who are overweight or obese are particularly vulnerable to the impacts of imbalanced nutritional intake, because it can worsen pre-existing conditions like sarcopenia, which further contributes to the spiral of malnutrition.
Identifying and treating malnutrition
Malnutrition is often overlooked, and when overweight or obese people are affected, identifying it can become increasingly difficult. One easy way to find out whether your loved one or patient is at risk of malnutrition is to use the Malnutrition Screening Tool (MST) .
All you have to do is ask your patient or loved one two questions, and add up the answer scores to see whether they’re at risk of being malnourished. You can download the MST here.
Most types of malnutrition can be successfully prevented by following a balanced diet of whole foods, but, if someone you know scores 2+ on the MST, take action. Start treating them using our 9 tips for fighting malnutrition and book an appointment with an Accredited Practicing Dietitian or your GP.
Remember: malnutrition isn’t always visible. It isn’t always obvious. Sometimes the signs can be as simple as eating less food, or unintentionally losing a little bit of weight. Most importantly, malnutrition can affect anyone. You don’t need to be underweight to be malnourished, and even overweight or obese people can be at risk.
It’s time for us, as Australians, to change the way we think about body shape and healthiness. You can’t judge someone’s nutritional status by looking at their body. It’s that simple. So, if you think a patient or a loved one might be at risk of malnutrition, it’s time to speak up. Book them an appointment with a professional dietitian, and stop the spiral of malnutrition before it starts.
Medical information on FlavourCreations.com.au is merely information and is not the advice of a medical practitioner. This information is general advice and was accurate at the time of publication. For more information about nutrition and your individual needs, see your GP or an Accredited Practising Dietitian.
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 Dietitians Association of Australia (2019, March) Royal Commission into Aged Care Quality and Safety. Dietitians Association of Australia. https://dietitiansaustralia.org.au/wp-content/uploads/2019/03/DAA_Royal-Commission-Aged-Care_Mar-2019_Final.pdf
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