Skipping meals or extending the time between dinner and the next day’s food has become a common health strategy.
Yet a long-term Swedish study suggests that older adults who routinely spent many hours between meals tended to develop chronic diseases faster. The relationship was strongest among people in their late 70s and beyond.
Researchers from Karolinska Institutet studied 2,981 people aged 60 and older in Stockholm.
Some participants were followed for up to 15 years, giving researchers a rare opportunity to examine meal timing alongside changes in health over a large part of later life. The results challenge the idea that fasting advice can be applied equally across all ages.
Intermittent fasting has attracted attention because it changes when people eat rather than necessarily telling them exactly what foods to choose.
Popular approaches may involve eating only during a limited daily window or leaving a long overnight period without food. Studies have explored whether these patterns can affect weight, insulin and other measures of health.
But older bodies face challenges that are less common earlier in life. Appetite can decrease, muscle is easier to lose and recovering from illness can take longer. Many older adults also take several medicines or live with conditions that affect digestion, movement or the ability to prepare food.
The researchers therefore focused on the longest interval between meals during a typical 24-hour day. Participants reported the times at which they usually ate. From these reports, the team estimated how many hours normally passed between meals.
The data came from the Swedish National Study on Aging and Care in Kungsholmen. This research project collects detailed information about aging and health among people living in Stockholm. For the new analysis, researchers tracked the accumulation of chronic diseases over time.
Developing several long-term illnesses is common in later life. A person might, for example, live with high blood pressure, heart disease and another chronic condition at the same time. Researchers wanted to know whether usual meal spacing was connected with how quickly this burden of disease increased.
A notable difference appeared between people with relatively moderate meal gaps and those with very long ones. Participants whose longest daily interval was 14 to 24 hours accumulated chronic diseases more rapidly than people whose longest interval was six to 11.5 hours. The association became particularly strong in the oldest participants.
For people aged 78 and above, the relationship was more pronounced. This does not prove that long fasting periods are dangerous after age 78, but it suggests that the balance between possible benefits and risks may change with age. The nutritional needs of an older person can differ substantially from those of a younger adult.
The researchers also separated illnesses into broad categories. Long intervals between meals were associated with faster accumulation of cardiovascular diseases. These include conditions affecting the heart and blood vessels.
A similar association appeared for neuropsychiatric diseases, a broad category involving neurological and mental health conditions. In contrast, the researchers did not observe a clear relationship with musculoskeletal diseases affecting bones, muscles and joints. This variation may eventually provide clues about the biology behind the findings.
There are several possible explanations, but the study was not designed to determine which is correct.
Very long periods between meals might make it harder for some older adults to consume enough energy, protein, vitamins and minerals. Adequate nutrition becomes especially important when the body is trying to preserve muscle and recover from illness.
On the other hand, the direction could be reversed. People developing chronic disease may naturally begin eating less often because they feel tired, unwell or less hungry. In that case, long meal gaps would partly be a sign of worsening health rather than the cause.
Social factors could also play a role. An older adult who lives alone may skip meals because cooking for one person feels difficult or unappealing. Problems with money, transportation, teeth, swallowing, memory or access to food can also influence when and how often someone eats.
This makes the study very different from a controlled experiment in which researchers deliberately assign people to fasting or non-fasting diets. The investigators observed naturally occurring eating patterns. They can identify associations, but they cannot prove that changing the number of hours between meals would change a person’s disease risk.
The findings were published in the Journal of Internal Medicine. Last author Adrián Carballo Casla, a researcher at Karolinska Institutet’s Aging Research Center, noted that much of the existing fasting research has involved younger or middle-aged adults. His team’s results suggest that older populations need to be studied separately.
This point matters because dietary trends can spread faster than scientific evidence.
A fasting schedule that produces certain benefits in a healthy 40-year-old may not have the same effects in an 80-year-old who has low appetite, takes several medicines and is trying to prevent muscle loss. Age can change both the risks and benefits of nutritional strategies.
The study does not show that older adults should constantly snack or avoid an ordinary overnight period without food. Nor does it establish that six to 11.5 hours is the perfect interval for everyone. The researchers compared patterns within this population rather than prescribing an ideal schedule.
Another limitation is that participants reported their own meal timing. Self-reported information can be imperfect, and people may change their eating habits as they age. The study would be stronger if meal timing and food intake were repeatedly and objectively measured throughout follow-up.
The researchers also need to know more about what participants ate. Two people can have the same 14-hour interval between meals while consuming very different amounts of calories, protein, vegetables and other nutrients during the remaining hours. Food quality and total intake may be just as important as timing.
Despite these limitations, the research has major strengths. Nearly 3,000 older adults were included, and some were observed for 15 years. This long time frame allowed the team to examine gradual changes in chronic disease burden rather than relying on a short-term measure.
The results are best seen as a warning against assuming that longer fasting is automatically healthier.
They suggest that the oldest adults may respond differently and deserve specific research rather than recommendations borrowed from younger groups. Randomized trials could eventually test whether altering meal timing changes health outcomes in later life.
Until then, older adults should consider meal timing as only one part of nutrition. Getting enough protein, energy and essential nutrients, maintaining a healthy weight and managing existing diseases may be more important than following a fashionable fasting window.
Anyone who is frail, losing weight unintentionally or managing several medical conditions should seek individual advice before deliberately extending fasting periods.
Overall, the study adds an important age-related twist to the fasting debate. Long gaps between meals were linked with faster disease accumulation, particularly after age 78, but they have not been proven to cause it.
The findings make a strong case for studying nutrition in older adults on its own terms rather than assuming that eating strategies have the same effects throughout life.
Source: Karolinska Institutet.
