Energy balance is an important concept for understanding weight management. The body uses energy all the time, even when at rest or sleep. Energy balance is when the energy obtained from diet (measured in calories) meets the energy that the body needs.
As an individual with neuromuscular disorders stops walking, energy needs often decrease making obesity a greater risk. As an individual experiences respiratory decline, energy needs increase making undernutrition a greater
As adults switch to permanent ventilation, breathing difficulties decrease and nutritional requirements also decline. A study by Gonzalez-Bermejo in 2004 on adults with DMD identified that those who are on permanent ventilation had a lower resting energy expenditure, suggesting they need fewer calories. This explains why some people start to put on weight once they have 24/7 ventilation.
Energy balance can also change in the short term, as energy requirements are increased during illness and infection, after surgery and when breathing becomes more difficult.
In children and some young adults, care must be taken to avoid obesity, particularly when using steroids which can be associated with increased appetite and weight gain. Weight gain can sometimes be an issue for older adults as well, where they are permanently ventilated and in good health.
Obesity causes problems with breathing and mobility as the body must
work harder to use muscles, and it also makes it harder for moving and
handling by family and carers. If necessary, weight reducing diets may
be needed to restore a healthy weight.
It is important that a proactive approach is taken before a child or adult
becomes overweight. It’s easier, and healthier to prevent weight gain in
the first place than to lose weight afterwards!
For older teenagers and adults, under-nutrition is a significant risk and individuals can quickly become underweight. This may be due to loss of appetite associated with respiratory problems, difficulties with chewing and swallowing or a result of increased nutritional requirements from increased work of breathing.
Under-nutrition adversely affects respiratory muscles, reducing muscle
mass and strength. It additionally affects immune function, wound healing, sensitivity to oxygen (prolonging ventilator weaning) and psychosocial function.
It can often be challenging for adults and their families to recognise when they are becoming underweight, particularly if they are used to watching what they eat and keeping weight down. It may require a shift in mind-set.
What do I need to look out for?
In reviewing nutritional requirements, it is important to consider a
number of factors:
Weight – where possible adults with neuromuscular disorders should be weighed regularly and attention should be paid to any unintentional weight changes over time. Weight is the best indicator of achieving energy balance so is important to monitor regularly, every 6 months if stable and more regularly if unwell. It is important to consider other signs of weight loss if it is difficult to get weighed regularly such as the fit of your clothes.
Nutritional intake/appetite – adults with NMD should monitor how much they are eating compared to normal, including snacks in between meals, and in particular how often meals are left unfinished.
Fatigue or difficulty with eating – this can result from increasing problems with chewing and swallowing or respiratory problems. This may be an early sign that weight loss could become a problem.
Changes in energy needs – If fighting an infection or starting to need
use of the ventilator more during the day, adults with NMD are likely to
need more energy and more calories than usual.
Where can I get help?
Where possible, adults with NMD should attend an adult clinic specialising in DMD which has access to a specialist dietitian or speech and language therapist to allow tailored advice and multidisciplinary management. If this is not possible, a referral to local dietetic and speech and language therapy services should be made.
How to get weighed
Some clinics use a weighing scale which weighs the individual in their wheelchair and subtracts the weight of the wheelchair from this. Care must be taken to ensure consistency by removing any additional equipment, bags etc. on the wheelchair each time.
Where an individual gets a new wheelchair or makes modifications to it, it will be necessary to weigh the wheelchair separately the first time it is used on the scale, in order to compare previous weight history.
Some clinics and community teams use a weighing scale that attaches to a hoist/Hoyer lift and weighs the individual directly. These can also be purchased privately.
Strategies to lose weight
• Reduce any sugary drinks e.g. fizzy drinks, juice, alcohol. Focus on water as the main drink with some dairy (e.g. milk) for bone health.
• Reduce frequency of high calorie, low nutrient foods e.g. takeaways especially fried food, bakery products e.g. croissants, Danish pastries, muffins, crisps, chocolate
• Include low calorie snacks e.g. vegetable sticks (raw or steamed) with salsa, berries
• Include lean proteins at meals and snacks: e.g. tin tuna, boiled eggs, chicken
• Focus on having 2 servings of fruit and 5 servings of vegetables daily.
• Eat 3 regular, balanced meals a day and plan your meals for the weeks.
Strategies to gain weight
• Focus on increasing the nutrient density of foods rather than the amount of food you eat e.g. adding fats (butter, margarine, oil, cream) and protein (milk powder, full cream dairy, meat/chicken/fish, eggs, tofu)
• Eat more nutrient-dense snacks e.g. full fat dairy (yoghurt, cheese, custard), peanut butter on crackers or bread, sweet or savoury muffins
• Eat and drink more milky drinks/condensed soups e.g. flavoured milk
• You can be prescribed high calorie drinks and liquid supplements in addition to normal meals by your dietitian.
What does BMI mean for me?
BMI scales have been shown to be inadequate in diagnosing obesity in children with DMD (Pessolano et al. 2003). As neuromuscular disorders progress in adulthood, the loss of muscle also makes it difficult to reliably assess healthy weight using BMI.
NICE guidelines (2017) define malnutrition as a BMI of less than 20 kg/m2 and unintentional weight loss of greater than 5% within the last 3-6 months. Obesity is defined as more than 25 kg/m2. Using this scale, many older adults will be classified as underweight. For adults in this category, it is vital to access dietetic services to ensure appropriate advice can be given to prevent under-nutrition. However, even after these interventions, adults may struggle to reach a “normal” weight on a BMI scale when adequately nourished.
More research is needed to identify a NMD-adjusted BMI scale or similar tool which accounts for muscle loss in determining a healthy weight. For now, BMI guidelines can be a useful guideline but must be interpreted in the context of individual weight history, energy requirements and nutritional intake.