Pressure Ulcers and Obesity
Severe obesity raises the risk of pressure ulcers because of immobility, moisture in skin folds, friction and shear, while rapid weight loss can raise it again through loss of muscle and protein.
Plain English
Patient-Friendly Explanation
A pressure ulcer, sometimes called a bedsore, is an area of skin and the tissue beneath it that is damaged by sustained pressure. It usually forms over a bony point such as the base of the spine, the heels or the hips, and it develops when a person cannot shift their own weight often enough. Several things make it more likely: lying or sitting in one position, damp skin, the friction and shear of being moved in bed, poor nutrition, diabetes and reduced blood flow. Body weight sits at both ends of the problem. People with severe obesity carry more load over those bony points, may find it physically hard to turn or be turned, and often have warm, moist skin folds where the skin breaks down. A large analysis that pooled eleven studies and more than thirty-one thousand hospitalised adults found that, compared with normal weight, being underweight, obese or severely obese all raised the risk of a pressure injury, with the risk raised at both extremes of weight. In intensive care, one cohort found an ulcer incidence of about six per cent in patients of normal weight and about ten per cent in those with extreme obesity. Doctors use a scored checklist called the Braden scale to judge risk, and body weight is now read alongside it. The risk does not stop once weight comes down. After bariatric surgery or a very low-energy diet, the loss of muscle, protein and micronutrients can leave the skin less able to repair itself, so the same person can be at risk from a different direction. Prevention is practical rather than complicated: regular changes of position, the right width of chair, mattress and hoist, keeping skin folds clean and dry, treating incontinence promptly, and making sure there is enough protein, fluid and vitamin C in the diet, especially while weight is falling quickly.
Medical
Clinical Definition
Pressure ulcers (pressure injuries) result from prolonged or repeated pressure, shear and friction over bony prominences, which causes ischaemic damage to skin and deeper tissue; they are staged from non-blanchable erythema through to full-thickness loss involving muscle and bone. Established risk factors include immobility, older age, diabetes, reduced perfusion, incontinence, moisture, malnutrition and impaired sensory perception, and risk is assessed with instruments such as the Braden and Norton scales. Obesity contributes through increased interface pressure over bony points, reduced mobility and difficulty with repositioning, moisture and maceration in skin folds, impaired lymphatic drainage, and in severe obesity reduced capillary density in adipose tissue. The epidemiological relationship is non-linear. A dose-response meta-analysis of 11 observational studies with 31,389 hospitalised adults found a J-shaped association between body mass index and pressure injuries, with odds ratios versus normal weight of 1.70 (95% CI 1.50-1.91) for underweight, 1.12 (95% CI 1.02-1.24) for obesity and 1.70 (95% CI 1.13-2.55) for morbid obesity. An intensive-care cohort reported ulcer incidences of 8.6 per cent in underweight, 5.5 per cent in normal weight, 2.8 per cent in obese and 9.9 per cent in patients with severe obesity, and among patients whose Braden mobility and friction/shear subscales were both high risk, the prevalence of ulcers was 79 per cent in the obese group against 50 per cent in the non-obese. Analysis of 21,835 critical care records found an approximately U-shaped curve with the lowest risk at a body mass index of 27.5 kg/m2 and, either side of that point, an 8.6 per cent increase in risk per unit below and a 1.4 per cent increase per unit above. Adding body mass index to the Braden score moved the area under the curve only from 0.68 to 0.71, so weight is treated as additional context rather than a replacement for the score. Bariatric surgery adds a second, later mechanism: rapid weight loss with inadequate protein and micronutrient intake causes loss of lean mass and impaired wound healing, and pressure injuries after bariatric surgery are reported in patients whose body mass index is still elevated. Prevention rests on scheduled repositioning, appropriate bariatric beds, chairs and transfer equipment, skin-fold hygiene, moisture management, and documented protein, fluid and micronutrient adequacy through the period of rapid weight loss.
Key Insight
Why It Matters
Skin is under strain at both extremes of body weight, and the risk shifts rather than disappears during rapid weight loss - which is why protein, skin-fold care and regular repositioning matter throughout a weight programme, not only at the end of it.
Sources
Reviewed against standard medical references.
Medically reviewed by
Family Physician & Registered Acupuncturist, Accord Medical Clinic. MBBS (NUS), Graduate Diploma in Family Medicine (NUS), Graduate Diploma in Acupuncture (Singapore College of TCM).
Last reviewed: October 2026
This page is general health education, not medical advice. Whether any treatment is appropriate for you is a decision made in consultation after assessment.
