To lose or not to lose? Weighing up the evidence

Do you ever find yourself worrying about your weight or the weight of your family members? What is a healthy weight range? Does it differ across the lifespan?

The Body Mass Index, or BMI is an indication which measures your weight in kilograms divided by your height in meters squared (weight kg/height m2). The World Health Organisation (WHO) has set the parameters of 18.5–24.9 kg/m2 as the healthy weight range; 25-29.9 kg/m2 as overweight; 30 kg/m2 and above as obese [1].

These ranges require careful interpretation, particularly if you are over 65 years of age or caring for someone over 65 years. Body composition changes with ageing – muscle mass and strength declines, fat mass is higher and there are changes in stature. The BMI does not account for these changes.

It is supported in the scientific literature that the WHO reference ranges are not appropriate for older adults [2]. Studies show that a BMI less than 22 kg/m2 may lead to poorer health outcomes and lower life expectancy [3]. Recommendations for upper limits vary from 27–30 kg/m2.

To lose even small amounts of weight (say 0.5 kg a month), an overweight, inactive person would need to follow a very strict diet that cannot provide enough nourishment to maintain health and quality of life, with the risk of muscle wasting, infections and associated poor outcomes. A focus on weight maintenance is more important, as well as regular exercise to maintain or improve muscle strength and balance [4].

If you are concerned about unusual weight gain, ensure you discuss this with your medical practitioner. If you are caring for an elderly person who is frail and may be losing weight, it is important to remember that dietary guidelines recommending consumption of a variety of breads, cereals, fruits and vegetables, dairy and lean meats, with low fat, reduced salt options do not apply. The frail elderly need energy-dense, high protein, higher fat meals with good flavour and aroma to maintain appetite, weight and reduce the risk of malnutrition, falls, infection, pressure ulcers, cognitive and functional decline.

Energy-dense, high protein meal ideas include:

• adding full cream milk or cream to cereal/soups/desserts for additional energy and protein
• adding 1-2tbsp of milk powder to milk drinks and soups for extra energy and protein
• adding protein-rich beans, legumes, cheese and meat to improve the energy and protein profile of meals
• eggs! Eggs on toast are a highly nutritious quick breakfast, lunch or dinner.

If you are concerned that you or someone you care for are losing weight, include a powdered supplement drink complete in vitamins and minerals at least twice daily and talk with your medical practitioner.

References

1. WHO, Physical status: the use and interpretation of anthropometry. Report of a WHO Expert Committee. Technical Report Series, 1995. 854. 2. Cook, Z., et al., Use of BMI in the assessment of undernutrition in older subjects: reflecting on practice. Proceedings of the Nutrition Society, 2005. 64: p. 313-317. 3. Rajala, S.A., et al., Body weight and the threeyear prognosis in very old people. International Journal of Obesity, 1990. 14: p. 997-1003. 4. Henwood, T.R. and D.R. Taaffe, Short-term resistance training and the older adult: the effect of varied programmes for the enhancement of muscle strength and functional performance. Clinical Physiology and Functional Imaging, 2006. 26(5): p. 305-313.