Articles Clinical Blog

Busting Myths – What is the impact of body weight on pressure ulcer risk?

It is well documented that there are several factors that increase a person’s risk for developing pressure ulcers, these include: mobility/ activity, tissue perfusion, age, co-morbidities such as diabetes, illness, poor nutrition and hydration (Coleman et al, 2013). Some risk assessment tools include BMI or weight loss/ gain within their risk factors, but the evidence for this inclusion has been interpreted differently over time and in different settings, which suggests there is more to consider than weight alone. 

Is a person at more risk of developing pressure ulcers if they are underweight, overweight, or obese? 

Is weight alone a risk factor, or is it that other co-morbidities associated with weight gain or loss are the underlying factors?

The Underweight person
It is probably easier to understand why someone who is underweight would be at high risk for developing pressure ulcers; they tend to have more prominent bone structure which is easily exposed to pressure from any surface or device in contact with the person’s skin. Without adequate adipose (fatty) tissue protection the vulnerable tissues and vessels are more susceptible to tissue occlusion and ischaemia than in someone with more protective tissue covering their bony prominences. 

Someone who is very underweight is likely to have poor tissue nutrition as all their nutritional reserves centre on their vital organs to maintain essential life preserving function. This will lead to fragile skin and reduced reserves to supply nutrients to these vulnerable skin areas. 

A meta-analysis paper (a study of multiple sources of evidence which draw a consensus conclusion) by Alipoor et al in 2021 found that patients who were underweight were significantly 2.3 times more likely to develop pressure ulcers when compared to “normal weight” people.

Care needs for this group of patients will require holistic assessment of nutritional needs and a careful choice of appropriate support surfaces that gently support the light weight person, enveloping their vulnerable bony prominences to enable pressure redistribution. 

The over-weight, obese or extremely (Morbidly) obese person
Interestingly, Alipoor et al (2021) also found that there was a significantly lower risk of developing pressure ulcers in the “overweight” group with evidence suggesting 0.7 times less risk than someone of normal weight. 

It’s important to recognise this group is separate from those classified as obese or extremely (morbidly) obese. Several studies have identified that people with a BMI of over 25 but less than 40 have enough protective adipose or fatty tissue to lower their risk of pressure ulcer (Hyun et al, 2014; Alipoor et al, 2021). 

Having adequate adipose tissue protection over bony prominences, means that any pressure exerted over these areas from sitting or laying is naturally re-distributed over the larger body surface area, thus reducing the density of pressure over the small areas of bony prominences. Additionally, subcutaneous fat is able to reduce the mechanical forces on underlying tissues from shearing.

Recent studies also suggest that those in the obese and extremely (morbidly) obese groups were found to have no significantly higher risk than those in normal weight groups, based on their weight alone (Wurkum et al, 2022). 

However, someone who is obese does have other risk factors, adipose tissue may have a compromised blood supply and therefore poor nutrient delivery to the skin (Gu & Xu, 2013). Just because someone is overweight or obese, does not mean they have good nutrition, in fact often the opposite is true (Ness et al, 2018). Obesity is often because of a poorly balanced diet and regardless of body weight, 30-50% of patients in hospital and care settings are considered to be mal-nourished. Malnourishment results in a reduced immune system, impaired collagen synthesis (essential for tissue repair), increased subcutaneous tissue and muscle atrophy and has been long recognised as a risk factor for pressure ulcer development (Alipoor et al, 2021). 

Obesity has been long associated with health issues including diabetes, stroke and heart disease – all known risk factors for pressure ulcer development (Baumgarten et al, 2006 in Hyun et al, 2014) and with an increasing obesity in the population there is an associated increase with these health conditions. Hyun et al (2014) identify that extremely (morbidly) obese patients in their critical care unit study were more likely to develop pressure ulcers than non-obese patients, but this may be due to reduced tissue perfusion seen in critical care patients due to the use of vasopressor medications adding to an already limited vascular perfusion of excess adipose tissue as well as all patients in the study had underlying medical conditions already known to increase pressure ulcer risk; rather than their body mass index alone. This is supported by Wurkum et al (2022) who found that although there was no significant difference in the obese and morbidly obese group prevalence of pressure ulcers, those in the morbidly obese group were more susceptible in the early stages of their critical illness; whereas in a study with a care home cohort of patients, Shubing et al (2013) found that elderly overweight residents were more likely to develop pressure ulcers during a prolonged stay in a care setting. 

Skin hygiene challenges
Someone who is very overweight/ obese may have difficulty in maintaining good skin hygiene and patients report difficulties in reaching areas of their body to wash adequately, while others find innovative ways of reaching all areas that need washing. Poor skin hygiene will increase risks for skin breakdown due to moisture and skin infections (Dial et al, 2018); as TVNs we see this frequently in clinical practice, particularly when an obese person becomes unwell or during a period of hot weather when sweating becomes a factor. Dial et al (2018) demonstrated the importance for health care professionals to understand their obese patients’ usual routines so they can support with similar strategies to ensure continuity of cleansing and maintaining hygiene. 

Psychological challenges
For some people their body weight can have adverse impacts on their mental health and can result in low self-esteem, mood and ultimately motivation to change or care for themselves well. This can lead to an apathy to move and change position to relieve pressure, resulting in long periods of inactivity which in turn increases risk of tissue ischaemia due to prolonged pressure (Waterlow, 2005). There may be a need to involve psychological support services in the care of the obese person to help with improving mood and activity. 

Moving and handling challenges
A major impact which may increase an obese/ morbidly obese person’s risk of pressure ulceration is their ability to move or be moved. Where someone requires help to reposition, there can be a huge risk on the safety of healthcare professionals carrying out moving and handling. It is essential that a moving and handling risk assessment is carried out and a clear, documented guide is available for HCPs identifying how many staff are required for each activity and what equipment is needed. 

HCPs may wish to consider specialist bariatric equipment to aid repositioning and reduce interface pressures for obese / morbidly obese people in their care. 

In conclusion, the evidence and clinical experience suggests that body weight alone is only a risk factor for pressure ulcer development when a person falls into the underweight group. Patients who are overweight are less likely to develop pressure ulcers due to a protective layer of adipose or fatty tissue over their bony prominences. Obese and extremely obese people are more likely to develop pressure ulcers due to a combination of factors including poor nutrition, co-morbidities, and physical challenges of caring for themselves and for those caring for them. Ultimately a good pressure ulcer risk assessment involves a holistic review of the person, including their health, environment, and care needs. 

View OSKA’s range of bariatric products


Coleman S., Gorecki C., Nelson E.A., Closs S.J., Defloor T., Halfens R., Farrin A., Brown J., Schoonhoven L., Nixon J., 2013. Patient risk factors for pressure ulcer development: Systematic review. International Journal of Nursing Studies. 50 (7). p 974-1003.

Hyun S., Xiaobai L., Vermillion B., Newton C., Fall M., Pacharmon K., Moffatt-Bruce S., Lenz ER., 2014. Body mass index and pressure ulcers: improved predictability of pressure ulcers in intensive care patients. American Journal of Critical Care. Nov. 23 (6). Pp 494-500.

Alipoor E., Mehrdadi P., Yaseri M., Hosseinzadeh-Attar MJ., 2021. Association of overweight and obesity with the prevalence and incidence of pressure ulcers:a systematic review and meta-analysis. Clinical Nutrition. 40 (9). Pp 5089-5098

Wurkum JD., van Olffen A., Vaes PJ., van Gestel A., Vos P., Ramnarain D. 2022. The association between obesity and pressure ulcer development in critically ill patients: a prospective cohort study. Obesity research and Clinical Practice. 16 (1). pp 56-62.

Shubing C., Rahman M., Intrator O., 2013. Obesity and pressure ulcers among nursing home residents. Medical Care. 51 (6) pp 478-486

Ness SJ., Hickling DF., Bell JJ., Collins PF. 2018. The pressures of obesity:the relationship between obesity, malnutrition and pressure injuries in hospital inpatients. Clinical Nutrition. 37 (5). Pp 1569-1574. 

Gu P., Xu A., 2013. Interplay between adipose tissue and blood vessels in obesity and vascular dysfunction. Reviews in Endocrine and Metabolic Disorders 14 (1). Pp 49-58Dial M, Holmes J, McGownd R, Wendler C,. 2018. “I do the best I can”: personal care preferences of patients of size. Applied Nursing Research. 39 (Feb). pp 259-264.