Almost everyone reading this will have started a diet at some point in their life. There is a pervasive societal message that being thin is hugely important, but as we age, there can be serious harm to health and well-being from weight loss. Malnutrition and loss of muscle mass, from even intentional weight loss, can have an impact on physical function and independence. To stay healthy, older adults have specific dietary needs.
The ideal weight for older adults
In younger adults there is an established relationship between a lower body mass index and survival. Body mass index (BMI) is weight in kilograms divided by height in meters squared (kg/m2). This measure is not perfect as a young man who has a lot of muscles can have a BMI in the overweight range. For adults aged beyond their sixties, the group with the lowest mortality have a BMI of 23-30. Even in this age group, obesity (BMI>30) is still associated with higher mortality and disability. Unfortunately these studies don't track weight over a long period of time, so it is also not clear whether those who have always been slim have the same risk of mortality, and hopefully future studies will answer this question.
Protein and muscle
As we age, we do tend to slowly lose muscle and gain more fat, so a lower proportion of our body weight is made up of muscle. To maintain or even build muscle, older adults actually have a higher protein requirement than younger adults, of approximately 1.2g/kg. People who are frail or exercise a lot may actually need more protein. When older adults lose weight, there is a disproportionate loss of muscle. This puts people at risk of sarcopaenia, which is a loss of muscle that leads to trouble with daily functions, like standing from a chair and can increase the risk of falls.
Nutrition tip: Every meal should have a source of protein, like dairy, meat, eggs or legumes for the vegetarians.
Healthy fats
For a long time fat has been demonised, due to the higher number of kilojoules per gram. Healthy fats, like those found in salmon, olive oil and nuts, are actually a critical part of a healthy diet. A higher intake of healthy fats, particularly omega-3, can decrease the risk of heart attack and stroke. Studies have shown that a Mediterranean diet, with extra olive oil or nuts, can even lead to better performance on cognitive tests and so may offer some protection against dementia.
Fibre
Fibre is also critical to healthy ageing. For a long time it was thought that the main benefit of fibre was to maintain bowel regularity but now we know it does so much more. Fibre does decrease the risk of certain cancers, particularly bowel cancer, but it also has an impact on whole body health and can protect against diabetes and cardiovascular disease. Adequate fibre helps maintain a healthy gut microbiome and may protect against frailty. Processed foods tend to be very low in fibre. Foods that are naturally high in fibre include vegetables, oats and legumes.
Nutrition tip: Chia seeds can be added to porridge, yoghurt and even ice cream are an easy way to increase fibre and are also high in omega-3 fat.
Variety
Other than in the case of specific deficiencies, studies have repeatedly shown that vitamin tablets do not decrease mortality. It is easy to fall into habit and eat the same foods every day. Different foods will contain different micronutrients, so by eating a restricted diet, there is a risk of nutrient deficiency.
Nutrition tip: eat the rainbow! Including a variety of vegetables and fruit every day is the best way to give your body all the vitamins and minerals you need.
Make meal times social
The most enjoyable meals don’t just have good food, but great company. For people who live alone, it is easy to fall into the trap of poor nutrition, like subsisting on tea and toast. Older adults who are socially isolated often eat less food overall, risking unintentional weight loss. For those who live alone, it may seem like too much effort to make a nutritious meal for one, but trying to organise social gatherings at meal time could improve health by combatting loneliness and encouraging a better diet.
For most of us the most important thing in life is our health and independence, not a number on the scales. Restrictive diets are particularly dangerous in older adults because of the risk of muscle loss and nutritional deficiency. Making an effort to eat a big variety of vegetables and enjoying dairy, eggs, fish and olive oil can decrease the risks of frailty, dementia and cardiovascular disease. Inviting a friend over for salmon and salad (with avocado chocolate mousse for dessert!) is a great way to spend an evening and may even extend your life.
For more on the importance of choosing non-processed food:
https://www.healthambition.com/processed-foods/