Going for long periods without eating has become popular in recent years, with some people using fasting schedules in hopes of improving weight, blood sugar or overall health.
But new research from Sweden suggests that long gaps between meals may not have the same effects in older adults. People who regularly went longer between meals developed chronic health conditions more quickly over time.
The study was conducted by researchers at Karolinska Institutet and followed almost 3,000 older adults for as long as 15 years. The strongest association appeared among people aged 78 and older. The findings suggest that eating patterns that may be suitable for younger adults should not automatically be assumed to benefit people later in life.
Fasting generally means going for a set period without eating. Some people simply stop eating after dinner and wait until breakfast, while others follow plans that limit food to a smaller number of hours each day. These approaches are often described as time-restricted eating or intermittent fasting.
Research in younger and middle-aged adults has suggested that some forms of meal timing may help with weight control or certain measures of metabolic health.
However, aging changes the body in important ways. Older people can have different nutritional needs, lower muscle mass and a greater chance of living with several illnesses at the same time.
The Swedish researchers wanted to know whether the longest period between meals during a normal day was related to the development of chronic disease. They used information from the Swedish National Study on Aging and Care in Kungsholmen, known as SNAC-K. This long-running project follows older residents of Stockholm.
The analysis included 2,981 adults who were at least 60 years old when the study began. Participants provided information about when they usually ate during a 24-hour period. Researchers used those answers to estimate each person’s longest daily interval without a meal.
The participants were then followed for up to 15 years. Rather than looking at only one illness, the researchers examined how quickly people accumulated multiple chronic diseases. This is particularly relevant in older age because many people eventually live with several long-term conditions at once.
The results showed that longer gaps between meals were associated with faster accumulation of chronic diseases. The pattern was especially noticeable among people whose longest daily interval without eating was between 14 and 24 hours. They accumulated illnesses faster than people whose longest interval was between six and 11.5 hours.
The association was not limited to one category of disease. Longer meal gaps were linked with faster accumulation of cardiovascular conditions, which involve the heart and blood vessels. They were also associated with neuropsychiatric conditions involving the brain, thinking, mood or behavior.
However, researchers did not find the same association for musculoskeletal diseases. These conditions affect structures such as muscles, bones and joints. The difference suggests that meal timing may not relate to every part of health in the same way.
The relationship was most pronounced in adults aged 78 and older. This is important because very old adults may be particularly vulnerable to inadequate food and nutrient intake. They are also more likely to experience reduced appetite, frailty, muscle loss or medical problems that make eating regularly more difficult.
As people age, maintaining enough muscle becomes increasingly important. Age-related muscle loss can reduce strength, balance and independence and may increase the risk of falls. Regular opportunities to eat protein and other nutrients may therefore have different importance in an 80-year-old than in a healthy 30-year-old.
Long meal gaps could also be a sign of other problems rather than a direct cause of disease. An older person who is already becoming unwell may lose their appetite or skip meals. Depression, memory problems, dental difficulties, loneliness, limited mobility or difficulty shopping and cooking can all change eating patterns.
This is one reason the study cannot show that fasting caused people to become ill. It was observational, meaning researchers recorded participants’ usual habits and followed their health rather than assigning them to specific eating schedules. A connection between two factors does not prove that one directly produced the other.
Meal timing was also based on information participants reported about their usual eating habits. People may not remember their schedules perfectly, and eating patterns can change over a 15-year period. More detailed studies using repeated measurements would provide a clearer picture.
The research was published in the Journal of Internal Medicine. Adrián Carballo Casla of Karolinska Institutet’s Aging Research Center said much fasting research has focused on younger and middle-aged people. The new findings suggest that associations between fasting and health may differ at older ages.
This does not mean that every older adult must eat frequently or that a particular number of meals prevents disease. The study did not test a specific fasting treatment, and it cannot identify the ideal eating schedule for older people. Individual needs can vary greatly depending on health, medicines, body weight, activity and nutritional status.
The study nevertheless raises an important question about popular dietary advice. Health trends are often promoted broadly even when most of the research has been conducted in younger populations. Older adults should not necessarily copy eating patterns studied mainly in people decades younger than themselves.
A major strength of the research is its long follow-up. Following nearly 3,000 people for up to 15 years allowed the investigators to study how multiple diseases accumulated during aging rather than looking at health at only one moment. Examining different disease groups also provided a more detailed view of the association.
The main weakness is that cause and effect remain uncertain. Longer periods without food could contribute to poorer health, but declining health could also lead people to eat less often. Other social, medical and lifestyle factors may influence both meal timing and disease risk.
Future research will need to determine whether changing meal timing actually affects health outcomes in older adults. Studies should also examine nutrition quality, total calorie and protein intake, weight changes and reasons for skipping meals. These details may help explain why long intervals were associated with poorer outcomes.
For now, the findings offer a useful caution rather than a rule. Fasting may have potential benefits in some people, but longer is not necessarily better, especially in advanced age. Older adults considering major changes to meal timing may benefit from discussing their individual nutritional needs with a health professional.
Source: Karolinska Institutet.
