The Malnutrition Continuum

10 March 2021

The term ‘malnutrition’ may mean undernutrition to most of people. After all, who hasn’t heard of malnourished victims of famine or malnourished hospital patients? However, malnutrition is a much wider term covering not only undernutrition but also overnutrition, such as obesity and the diseases associated with it, as well as micronutrient deficiencies and excesses. This blog considers the importance of understanding the whole spectrum of malnutrition for effective action to improve nutrition and gives a background to our new position statement.


Our lives depend on nutrition

We have had to eat for as long as we have existed, and yet the science of nutrition is relatively new and we still have a lot to learn. The reason why appropriate nutrition matters is the direct link with health, wellbeing and life. Our lives literally depend on nutrition.

In Latin, the word ‘mal’ means ‘evil’ or ‘bad’. It is not difficult to guess, as we use other mal-words often (think maltreatment, malfunction or malice). So, malnutrition essentially means ‘bad’ nutrition. Although we can tolerate bad nutrition in the very short term quite well, in the long term, all types of malnutrition lead to poor health. The Global Nutrition Report warns that malnutrition is responsible for more ill-health globally than any other cause, including the following findings:

  • undernutrition explains about 45% of deaths among children under five
  • overweight and poor diets elevate the risk of non-communicable diseases, which in turn contribute to death and disability worldwide
  • health consequences of overweight and obesity contribute to 7.1% of all deaths
  • micronutrient deficiencies can negatively impact eyesight, bone growth and immunity


According to the World Health Organization, the term malnutrition refers to deficiencies, excesses, or imbalances in a person’s intake of energy and/or nutrients. Malnutrition, therefore, addresses three broad groups of conditions:

  • undernutrition, which includes wasting (low weight-for-height), stunting (low height-for-age) and underweight (low weight-for-age)
  • micronutrient-related malnutrition, which includes micronutrient deficiencies (a lack of important vitamins and minerals) or micronutrient excess
  • overweight, obesity and diet-related noncommunicable diseases (such as heart disease, stroke, diabetes and some cancers)


Malnutrition in all its Forms and the Double Burden of Malnutrition

The use of malnutrition to mean undernutrition is historical, as decades ago, undernutrition was the most prevalent version of malnutrition. Unfortunately, this has changed, and nowadays we have problems at both ends of the spectrum.

It may be helpful to imagine malnutrition as a continuum from undernutrition to overweight and obesity, with the possibility of micronutrient imbalances occurring at any point. In recognition of the whole spectrum of diet-related problems, authorities such as the World Health Organization, European Commission and Global Nutrition Report have been increasingly using the terms of ‘malnutrition in all its forms’ and ‘double burden of malnutrition’.



It is now recognised that undernutrition and obesity are intrinsically linked through four shared drivers: early life nutrition; dietary quality; food environments; and socioeconomic factors. Focusing on progress in these four areas, will improve all aspects of nutrition across all life stages. Double-duty actions, defined as actions that simultaneously address nutritional deficiencies and obesity and diet-related non-communicable diseases, have been proposed as a win-win solution to tackling malnutrition in all its forms.

Going even further, the most recent report of the Lancet Commission on Obesity recognised that obesity and undernutrition, as well as climate change, all have common drivers (food and agriculture, transportation, urban design and land use). The Commission also suggested that shared drivers require shared solutions. For example, promoting active transport would increase physical activity and reduce sedentary time (tackling obesity), improve food security by reducing emissions and catastrophic weather events (tackling undernutrition), and lower greenhouse gas emissions from polluting transport modes (tackling climate change).

What is Obesity Action Scotland’s contribution to all of this? Well, our work involves advocating for healthy weight through a strong focus on the food environment in Scotland, as demonstrated in our 2021 Scottish Parliament Election Manifesto. As the food environment is one of the common drivers for both undernutrition and obesity, this approach advocates for and promotes a comprehensive set of double-duty actions that will tackle malnutrition in all its forms.


Measuring malnutrition by BMI

How do we measure who is malnourished and who is not? Calculation of Body Mass Index (BMI) is one of the methods to determine nutrition status. BMI is a function of height and weight and BMI of 18.5 kg/m2 and under is classified as underweight, between 18.5 and 24.9 kg/m2 as healthy weight and 25 kg/m2 and over as overweight or obesity.

The Scottish Health Survey (2020) reported that BMI generally increased with age up to the age of 74 among all adults (increasing from 24.9 kg/m2 among those aged 16-24 to 29.1 kg/m2 among those aged 65-74) before decreasing to 27.9 kg/m2 among those aged 75 and over. Patterns of mean BMI by age did not differ significantly between men and women.

The chart below shows proportions of adults who were underweight (yellow), normal weight (blue), and had overweight or obesity (orange) in 2019 (the survey report was published in 2020). It is clear that the biggest proportion of people in all age groups, apart from the youngest, fall into overweight and obesity BMI categories. Therefore, at least according to BMI, the main malnutrition problem in Scotland is at the overweight and obesity end of the continuum.



Measuring malnutrition by diet

Another way to understand whether nutrition is appropriate is to look at diets. For individual people, dietitians can assess nutrition status in many ways, for example by anthropometric measurements, biochemical measurements or using dietary intake assessment tools such as questionnaires. On a population level, we have dietary surveillance programmes.

The dietary surveillance programme in Scotland monitors progress towards Scottish Dietary Goals (SDGs) and is led by Food Standards Scotland (FSS). Until recently, FSS conducted secondary analysis of the Living Costs and Food Survey Defra and the UK Office for National Statistics. Recently however, a pilot of Intake24, which is an online dietary recall system designed to collect detailed dietary intake data, was included in the Scottish Health Survey (SHeS) in 2018. Intake24 is a new methodology and direct comparison with the previous surveillance is not possible. However, the results broadly aligned with findings of other surveys, showing that we are not meeting the majority of the SDGs and that our diet in Scotland needs to change. Specifically, we need to eat less saturated fat and sugar and more fruit and vegetables and fibre.

The most recent data from the National Diet and Nutrition Survey (NDNS) (2016 to 2017 and 2018 to 2019), that includes a Scottish sample within UK survey, highlighted very similar dietary issues. Importantly, dietary inequities in Scotland exist: people living in the most deprived areas consume more sugary drinks, savoury and meat pies, sausages and burgers and less healthy food and drink than those living in the least deprived areas.

FSS have not highlighted any major dietary issues within specific age groups.  However, small differences in diet between the age groups exist, for example children in Scotland have less fruit and vegetables than adults (2.8 portions a day for children compared to 3.3 portions a day for adults). A recently published SACN statement on nutrition and older adults living in the community, using NDNS 2014/15-15/16 data, reported that:

‘there was some evidence of low micronutrient intakes, particularly in women and the 75 years and over age group; this was also seen in younger women (19 to 64 years). There was also evidence of poor status for vitamin D (particularly in those aged 75 years and over) and folate, and to a lesser extent for iron and vitamin B12, which was also seen in younger adults.’

Apart from these differences, the statement concluded that:

‘overall the NDNS data on diet, nutrient intakes and blood analytes for people aged 65 to 74 years and 75 years and over indicate that, similar to all UK adults, older adults exceed maximum recommendations for intakes of saturated fat, free sugars and salt and fail to meet recommendations for fruit and vegetables, fibre and oily fish.’

The most up-to-date NDNS data (2016-17 and 2018-19) indicates the same trends.


Implications for action on malnutrition in Scotland

Understanding of the whole spectrum of malnutrition across all age groups and life stages is key to effective action. Use of a historical definition of malnutrition, to mean only undernutrition, risks creating confusion and an unnecessary conflict in priorities and actions. In fact, a focus on tackling only one aspect of malnutrition could cause harm. Rue and Hawkes (2019) give the following example:

“Latin America and Egypt show that some social cash/food transfer programs aimed at reducing poverty and undernutrition have led to deteriorations in diet quality (e.g., excess intakes of energy- fat- and sugar-dense and micronutrient-poor foods) and rises in obesity/dietary-related-NCD risks”.

To tackle malnutrition, we need a systemic approach and work to make improvements in the four areas that are shared drivers for both over and undernutrition:

  • early life nutrition
  • dietary quality
  • food environments
  • socioeconomic factors

The first and most basic step to tackling malnutrition is across-the-board adoption of the up to date definition of the problem, as well as thorough understanding of its current local, national and global extent. This is why, as an organisation, we are adopting the World Health Organization’s definition of malnutrition. We wholeheartedly invite and urge anyone who works in this space to do the same. The next step will be collaborative action across the malnutrition spectrum.


Read Obesity Action Scotland's new Position Statement on Malnutrition