The usual healthy weight advice has been torn up for people who are over 65, at least in the UK. People in this age group are now being told that 鈥渋f you are slightly overweight, losing weight might not actually improve your health鈥�, (BDA).
While the version of the guidance aimed at the public doesn鈥檛 mention body mass index (BMI), which divides someone鈥檚 weight in kilograms by their height in metres squared, a report of supporting evidence cites studies that found the optimum BMI for older people is from about 25 kg/m虏 up to 30 kg/m虏.
That is in contrast to most health advice, which recommends that adults of all ages aim for a BMI of between 18.5 and 25.
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鈥淚 don鈥檛 think older people particularly focus on their BMI, but healthcare staff can be a bit obsessive about it,鈥� says at the BDA. 鈥淚t鈥檚 not unusual to see people in their 80s who have BMI of 28 [being] told to lose weight.鈥�
There are several reasons for people to aim for a higher weight as they get older, she says. One is that fat acts as an energy store that can be drawn on when people get ill and lose their appetite. 鈥淧eriods of ill health increase as you age,鈥� says Smith. 鈥淏y encouraging older adults to lose weight, you鈥檙e almost making them less resilient.鈥�
Another is that weight loss tends to cause loss of both fat tissue and muscle, with the latter raising the risk of falls and ill health. Muscle mass already tends to decline naturally with age, a process called sarcopenia.
A third factor is that people who go on a diet may become tired and less likely to stay physically active, which can further contribute to muscle loss. 鈥淚t鈥檚 better to stay fit and not worry so much about excess weight than to reach this arbitrary target of a BMI of 25,鈥� says at the University of Plymouth, UK, a co-author of the BDA report.
Additionally, those who care for older people and are aware of general healthy eating advice may buy them low-fat foods and avoid treats such as ice cream without considering if the person does, in fact, need to lose weight.
This can lessen older people鈥檚 enjoyment of their food, says Hickson. 鈥淚f you鈥檙e too restrictive, it can reduce the amount of pleasure people have [in eating]. Worrying about your cholesterol and saturated fat when you鈥檙e 85 probably isn鈥檛 the best approach.鈥�
The advice for adults of all ages to aim for a BMI of under 25 is common in most countries, but it isn鈥檛 based on clear evidence. It seems to have entered the medical orthodoxy .
In fact, population studies give varying estimates for the BMI range linked with the lowest rates of death, with most suggesting the optimum weight is in the 25 to 30 band, for all ages. The strongest evidence that a higher BMI is preferable comes from studies of older adults.
The new approach to weight advice for older people chimes with the , a medical guidelines body in England. Its advice on obesity management, updated in July, says healthcare staff should interpret BMI 鈥渨ith caution in people aged 65 and over, taking into account鈥� the possible protective effect of having a slightly higher BMI when older鈥�.
at Stanford University in California, who has long argued that the standard BMI categories are too low for all age groups, says these stances are a 鈥済ood start鈥�.
The debate over which is the healthiest weight for people of different ages will probably become more relevant with the growing use of weight-loss injections, says Flegal. These include Wegovy and Ozempic, which is approved for type 2 diabetes but is often given off-label for obesity. Recommended weight categories 鈥渦sed to make no difference, because even if [someone] wanted to lose weight, they probably could not. Now, you can really do it,鈥� she says.
