The Double Burden of Malnutrition: an Evolving Landscape

Published 05 October 2020

By Conor McCrink, Registered Dietitian


Malnutrition is both a cause and consequence of ill health, yet it is often under-detected and under-treated. Malnutrition refers to a state of nutrition in which a deficiency or excess of energy, protein and other nutrients leads to measurable adverse effects on body form, function and clinical outcomes (1). In the lead up to Malnutrition Awareness Week, this article will discuss the double burden of malnutrition; namely undernutrition and overnutrition. This article will explore the prevalence, consequences and clinical considerations for both states of malnutrition.


Undernutrition involves a reduced intake or uptake of one or more nutrients (2). The consequences of undernutrition have been extensively researched and include (3, 4):

  • Impaired immune function
  • Delayed wound healing
  • Increased GP appointments
  • Increased length of hospital stay
  • Muscle wasting which may affect respiratory function, cardiac function and mobility
  • Impaired psycho-social function including apathy and depression
  • Weakness which may reduce appetite and perpetuate undernutrition

Undernutrition is estimated to affect 3 million people in the UK (~5% of the adult population). Of those affected, approximately 1.3 million (~40%) are over the age of 65 (3). The associated health care costs in England are approximately £15.2 billion annually (5). 


Despite the terms ‘malnutrition’ and ‘undernutrition’ often being used interchangeably, it is becoming increasingly accepted that overnutrition should be included within the definition of ‘malnutrition’. Overnutrition refers to the supply of nutrients in excess of requirements, leading to an increase in body stores.

Excessive energy (calorie) intake is of particular concern in the UK, with recent data suggesting that 64% of adults in England are overweight or obese, with a high prevalence amongst older adults (65-74 years old) (6).

The rates of obesity have more than doubled over the past 25 years, placing considerable strain on public and national health services. For example, the latest figures show that NHS costs relating to overweight and obesity are £6.1 billion each year (7), with an expected rise to £9.7 billion by 2050 (8). On an individual level, excessive accumulation of metabolically active adipose tissue has been linked with a number of clinical consequences, including (9):   

  • Type II diabetes mellitus
  • Hypertension
  • Dyslipidemia
  • Stroke
  • Sleep Apnea
  • Psychological disorders such as depression and anxiety
  • Osteoarthritis

It also appears that obesity is associated with an increased mortality rate in patients diagnosed with COVID-19 (10).

Undernutrition and Overweight or Obesity

While overnutrition and undernutrition may appear at either end of the malnutrition spectrum, they are not always mutually exclusive. For example, the double burden of malnutrition can be seen on an individual level in the case of sarcopenic obesity (SO). SO is a medical condition which is defined as the presence of both sarcopenia (loss of muscle) and obesity. It is a significant predictor of all-cause mortality among older people, particularly hospitalised patients (11). 

This raises a challenge and paradox for clinicians to identify malnutrition in obese patients who may be nutritionally vulnerable, especially during periods of acute illness (12). While the best tools to identify such risk are yet to be agreed upon, awareness must precede change. We need to further educate healthcare professionals (HCPs) on the importance of using malnutrition risk screening tools in patients of all sizes and body weights.

The Impact of COVID-19

The unprecedented impact of the COVID-19 pandemic has posed many challenges to individuals and societies across the globe. While novel challenges have emerged, malnutrition persists, and is likely to become perpetuated by recent events (13).

Recent data from September 2020 suggests that 14% of UK families with children have experienced food insecurity in the past six months (14). The impact of COVID-19 on the food system has been pronounced, with food production, transport, sales and food access impaired as result of the pandemic (15).

Unemployment rates are on the rise, which can have an indirect impact on access to food and nutritional status. For example, a national survey of over 1,000 UK residents, conducted in June 2020, found that a quarter of UK adults have experienced difficulties accessing affordable food (16). There has also been a surge in the use of food banks since COVID-19 (17). Social isolation due to social distancing and quarantine measures is another concern, especially for vulnerable population groups (18). These all present significant risk factors for undernutrition.

Recent events also have the potential to impact the prevalence of overnutrition. For example, public health measures to mitigate the spread of COVID-19 (such as working from home and closure of sporting facilities and gyms) may increase sedentary behaviours, increasing an individual’s likelihood to gain weight. It has also been speculated that COVID-19 may impact psychological health, especially the incidence of stress, anxiety and depression, all of which can impact energy intake (19). Additionally, a greater dependence on eating at home could prove challenging for those with limited nutritional knowledge and cooking skills, which may shift dietary intake patterns towards less nutrient-dense, processed foods (20).

Tackling the Double Burden of Malnutrition: Are We Doing Enough?

It is easy to see why overweight and obesity has been prioritised at a political and public health level. As mentioned earlier, obesity is associated with an increased mortality rate in patients diagnosed with COVID-19. As a result, a new UK obesity strategy (7) has been developed, with a number of initiatives planned, such as voluntary calorie labelling for small businesses. The efficacy of such strategies, however, has been questioned by the British Dietetic Association (BDA), who state that the aetiology of obesity is complex and multifactorial. They emphasise that encouraging the population to achieve or maintain a healthy weight will be difficult, calling for a compassionate and non-stigmatising approach for long-term change (21).

Government initiatives such as the COVID Summer Food Fund, NHS volunteer responders, increased access to universal credit and furlough schemes are thought to have gradually improved the level of food security in recent months. However, the level of food insecurity remains elevated relative to pre-covid conditions, suggesting that further work is required (14). AGE UK recently released a statement highlighting the rising risk of malnutrition (undernutrition) during COVID-19 (22). Given that the health care costs associated with undernutrition are more than twice that of obesity, it raises the question of ‘are we doing enough?’ at a political level.


Unprecedented recent events have significantly affected dietary intake, which is likely to have a subsequent impact on nutritional status and malnutrition risk. While the government has prioritised tackling overnutrition, it could be argued that undernutrition has been somewhat overlooked, despite it having a significant impact at an individual and public health level.

HCPs play an important role in addressing the double burden of malnutrition during COVID-19 and beyond. This article has highlighted the importance of nutrition risk screening more than ever before. With reduced face-to-face contact, HCPs may be required to use subjective measures and clinical judgment to categorise malnutrition risk as opposed to objective measures such as the MUST screening tool (23). However, regardless of the screening tool used, it is imperative that we continue to screen and monitor all patients with or at risk of malnutrition.

Particular attention should be provided to those over the age of 65 who routinely suffer from the highest prevalence of malnutrition and the highest mortality rates due to COVID-19 (24). Once identified, malnutrition is typically treatable with adequate nutrition support. However, this requires a continuous and collaborative effort between HCPs, public health bodies and the government.