Spinal cord injuries – what’s a “healthy weight”?
Up to 66 – 73% of adults with a spinal cord injury are overweight and 30 – 45% are obese. 1, 2 These rates are almost double what is found in the general UK population, where 38% of adults are overweight and 26% are obese.3 Why the difference?
Body composition changes after a spinal cord injury
Any type of major trauma puts clients at very high risk of becoming overweight, whether that trauma is from a spinal cord injury, a brain injury or a complex orthopaedic trauma. In the initial acute phase after the injury, clients lose significant amounts of weight and muscle mass due to high levels of inflammation in the body, hormonal changes, a temporary increase to metabolic rate, reduced levels of mobility/physical activity and/or an inadequate protein intake. In the case of a spinal cord injury (and some brain injuries too), this muscle loss is further compounded when the injury prevents nerve stimulation (and thus voluntary movement) in certain muscles within the body.
The long-term impact of this muscle loss is significant, because after the acute phase of the injury is over (usually several months after the index event), metabolic rate typically starts to decline. From that point forward, the person’s metabolic rate becomes determined primarily by their level of muscle mass and how much physical activity that they do. That means the less muscle mass that someone has, the slower their metabolic rate is going to be and the higher their risk of becoming overweight in the future. Muscles that have atrophied from disuse, burn very few calories and clients with a spinal cord injury often have calorie needs ~50% of their pre-injury levels. Few people are aware of this and thus revert back to pre-injury eating habits which then results in weight gain.
What is even more problematic, is that the majority of post-injury weight gain is typically in the form of fat (often abdominal/visceral fat), which then increases the person’s risk of type 2 diabetes and cardiovascular disease. Carrying extra weight also makes it challenging for clients with a spinal cord injury to mobilise, self-transfer, engage in activities of daily living and can also have a negative impact on mental health.
Weight targets after a spinal cord injury
Given the risks associated with carrying excess body fat, clients need to know what an appropriate target weight should be after a spinal cord injury. Health professionals also need to be aware of when to refer on to a dietitian.
BMI is calculated as weight (in kg) divided by height (in meters) squared (kg/m2). This measurement correlates to percent body fat in the general population. However, clients with a spinal cord injury need to use a different BMI target range to account for the body composition changes outlined above (and their higher percent body fat).
Based on these adjustments, people with a spinal cord injury should have a maximum BMI of 22.0kg/m2.
To date, the minimum BMI target remains at 18.5kg/m2 (the same as for the general population), because an adjusted target has not yet been developed for people after a spinal cord injury. Any client with a BMI outside of the 18.5 – 22kg/m2 range should be assessed by a dietitian to determine their level of nutritional risk.
While BMI is a common language for health professionals, clients themselves may not find these targets particularly helpful, especially if they don’t know how tall they are or have difficulty making the BMI calculation. For that reason, adjusted “ideal” body weights can be used instead of the BMI.
- Paraplegia – take their ideal “healthy” pre-injury weight and subtract 4.5 – 6.8kg (or 10-15%).
- Tetraplegia – take their ideal “healthy” pre-injury weight and subtract 6.8 – 9kg (or 15-20%).
Option 3 – Focus on losing 5-10% of their current body weight (6)
If clients are carrying a significant amount of extra weight, sometimes the weight targets above are just not realistic for them. In these cases, making a goal to lose at least 5-10% of their body weight can help improve health parameters.
Option 4 – Waist circumference
Most of the risks associated with being overweight, come from carrying extra weight in the abdominal region. That means that waist circumference measurements can be effective for assessing clinical risk. Due to changes in core muscle tone, people with a spinal cord injury should keep their waist circumference under 94cm. 1 However, the bloating and abdominal distension associated with neurogenic bowel can skew this measurement and so it may not be appropriate for all individuals.
Neither of these measurements are considered appropriate after a spinal cord injury. Bioelectrical impedance (often used to calculate percent body fat) is not accurate in this client group, due to significant changes in fluid balance, constipation and/or urine withholding. Skin callipers are not accurate either, because they don’t measure visceral fat and so tend to underestimate someone’s fat mass.
Actions for case managers & solicitors
1) Ensure clients have access to appropriate scales
The above BMI/weight targets are only helpful when clients know how much they actually weigh. For links to wheelchair scales, platform scales and hoist scales, check out our previous blog post on, “Weighing wheelchair-bound, bedbound, and bariatric clients.”
2) Know when to refer to a dietitian
Answering yes to any one (or more) of the following questions suggests that a client should be referred to a dietitian.
- Has there been a 10% unintentional change in weight within the last 6 months (weight increase or decrease)?
- Does your client with a spinal cord injury have a BMI over 22kg/m2?
- Does your client have a BMI under 18.5kg/m2?
- Does your client have type 2 diabetes, high cholesterol, high blood pressure, constipation, diarrhoea, abdominal pain and/or a Grade 3 or 4 pressure sore (or other slow healing wound)?
To refer a client with a spinal cord injury for a comprehensive dietetic assessment of weight, food intake and health parameters, contact Specialist Nutrition Rehab at 0121 384 7087 or firstname.lastname@example.org.
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