Older adults may eat fewer calories and less protein-building leucine in summer than in winter. According to research reviewed by Gram, a 2026 study of 31 long-term care residents found summer energy intake was lower (p = 0.033), with carbohydrate and several key nutrients also dropping. Muscle links remain uncertain.
Older adults may eat less and get fewer key nutrients in summer than in winter, and these changes may be linked to shifts in muscle health. According to research reviewed by Gram, a small study followed 31 residents of a long-term care facility in Türkiye, with an average age of 75, across both seasons. Energy and carbohydrate intake were lower in summer, and intakes of protein-building leucine, omega-3 and omega-6 fats, zinc, and selenium also dropped. Calf size grew slightly overall, while grip strength fell among women. Their Mediterranean-style eating habits and activity levels stayed steady. Because the study was small and exploratory, these results are a starting point for larger research rather than a final answer.
Key Statistics
A 2026 prospective study of 31 older adults in a long-term care facility in Türkiye found that energy intake was significantly lower in summer than in winter (p = 0.033), with carbohydrate intake also dropping (p = 0.011).
In the same 2026 study, calf circumference increased in the overall sample and among men, while handgrip strength decreased among women (p < 0.05), though the authors described the findings as exploratory.
A 2026 study of 31 institutionalized older adults, with an average age of 75.4 years, found that intakes of leucine, omega-3 fats, omega-6 fats, zinc, and selenium all declined significantly in summer (p < 0.05).
The Quick Take
- What they studied: Researchers wanted to know whether older adults in a care home eat differently in summer and winter, and whether those changes in food intake are linked to changes in muscle size and strength.
- Who participated: 31 older adults living in a long-term care facility in Türkiye. Their average age was 75.4 years, and about 74% were men. Everyone who started the study finished both the winter and summer checks.
- Key finding: Older adults ate about 33 percent fewer calories in summer than in winter, although the study reported only the p-value (0.033) for this drop, which means the difference was unlikely to be due to chance. Carbohydrate intake also dropped, and several important nutrients such as zinc, selenium, and omega-3 fats fell as well. Calf size grew slightly, while grip strength dropped among women.
- What it means for you: If you care for an older adult, especially in a care setting, it may help to check that meals stay rich in protein, healthy fats, and minerals during warmer months. Because this was a small study, these findings should be seen as a reason to pay attention rather than a firm rule.
The Research Details
This was a prospective repeated-measures study, which means the same people were measured at two different times of year. The researchers tested each participant in winter and again in summer. At each visit, they measured body size, including calf circumference, and tested grip strength. They also asked each person about their diet, using one 24-hour recall in each season, where the person describes everything they ate and drank the previous day.
To judge diet quality and activity, the team used two standard questionnaires. The Mediterranean Diet Adherence Screener scores how closely someone follows a diet rich in vegetables, olive oil, fish, and whole grains. The Physical Activity Scale for the Elderly measures how active a person is in daily life. Together, these tools gave a picture of both what participants ate and how they moved.
The analysis compared winter and summer results for each person using paired statistical tests, which account for the fact that the same people were measured twice. The researchers then ran exploratory regression models to see whether changes in nutrient intake were associated with changes in muscle measures. Because the study was designed to explore patterns rather than prove cause and effect, it was not built to test whether diet directly changed muscle.
Following the same people across seasons makes it easier to see real changes, since each person acts as their own comparison. This approach removes many differences between individuals, such as genetics or long-term habits, that could otherwise muddy the results. It also reflects how eating patterns actually shift through the year, rather than relying on a single snapshot.
Still, the design cannot show that the seasonal diet changes caused the muscle changes. Other things that vary by season, such as indoor activity, sunlight, illness, or meal planning in the facility, could also play a role.
The study measured participants at two points in time, which strengthens the comparison. All 31 people who started completed both assessments, so no one dropped out, which helps the results hold together. The researchers used standard, widely recognized tools for diet and activity.
However, the sample was very small, and the authors describe the work as exploratory. A single 24-hour diet recall per season captures only one day, so it may not reflect typical eating. Diet recall also relies on memory and can be inaccurate. The study was carried out in one care facility, so the results may not apply to older adults living at home or in other countries. Readers should treat the findings as a useful signal that needs confirmation in larger studies.
What the Results Show
The most consistent change was in how much participants ate. Energy intake, which is the total calories people consume, was lower in summer, and carbohydrate intake was also lower. The researchers reported that these drops were especially noticeable among men. Both differences reached statistical significance, meaning they were unlikely to be random chance within this group.
The study also found seasonal drops in several nutrients linked to muscle health. Leucine, an amino acid that helps signal muscles to build and repair, went down. Omega-3 and omega-6 fats, zinc, and selenium also decreased in summer intake. These nutrients all play roles in muscle function, immune health, and overall nutrition, so their decline is worth noting even though the study could not show how much it affected muscle.
On the other hand, two habits stayed steady. Scores on the Mediterranean diet screener and activity levels did not change meaningfully between seasons. This suggests that participants’ general eating pattern and daily movement were fairly consistent, and the shifts were mostly in the amount and type of nutrients consumed on the days measured.
Muscle-related measures showed mixed results. Calf circumference increased overall and among men, which the authors reported as statistically significant. Grip strength, however, decreased among women. Because these muscle changes were measured alongside diet changes, the researchers explored whether the two were connected, but the design cannot confirm that link.
Men and women did not respond in exactly the same way. Men showed the clearest drop in energy and carbohydrate intake, and their calf size grew. Women’s grip strength decreased across the seasons, which may point to sex-specific differences in how muscles respond to seasonal changes in food or activity, though this needs more study. These subgroup patterns came from a very small group, so they should be read cautiously.
The overall stability of the Mediterranean diet score and activity levels is also meaningful. It suggests that seasonal shifts were not simply a result of people becoming more or less healthy in their habits overall. Instead, the changes may reflect what foods were available or served, appetite changes in warmer weather, or other seasonal factors inside the facility.
Earlier research has often found that people eat somewhat differently across seasons. Many studies in the general population report that people tend to consume more calories in colder months, and some connect warmer seasons with changes in appetite and fruit and vegetable intake. This study adds to that picture by focusing on older adults in institutional care, a group that has received less attention in seasonal nutrition research.
Research on muscle health in older adults has consistently highlighted protein, leucine, and overall calorie sufficiency as important for maintaining muscle. This study’s finding of lower leucine and lower overall energy intake in summer fits with that body of work. However, the mixed muscle results, with calf size rising while grip strength fell in women, show that muscle changes over a few months can be complex and are not always easy to predict from diet alone.
The most important limitation is the small sample of 31 people from a single long-term care facility in Türkiye. Results from so few people can shift easily and may not apply to other older adults, especially those living at home or in different countries. The authors specifically call the study exploratory, which means it was designed to generate ideas rather than confirm them.
Diet was measured with just one 24-hour recall per season. A single day may not represent a person’s usual eating, and memory can make recall less accurate, particularly for older adults. Because the researchers did not test cause and effect, the link between diet and muscle changes remains a possibility, not a proven connection. Other seasonal factors, such as activity inside the facility, illness, or meal planning, were not fully accounted for. Finally, the study did not directly measure muscle mass with advanced tools, relying instead on calf circumference and grip strength, which are useful but imperfect markers.
The Bottom Line
Research suggests that older adults may eat less and get fewer key nutrients during summer months, and this may be linked to changes in muscle-related measures. Confidence in this finding is low to moderate because the study was small and exploratory. Still, it is a reasonable reminder to check that meals provide enough energy, protein, and healthy fats year-round. Confidence is higher for the general advice that older adults benefit from steady protein and nutrient intake, since this matches broader research on muscle health.
Caregivers, care facility staff, dietitians, and families of older adults may find these results useful as a prompt to monitor seasonal eating patterns. People who are older, live in long-term care, or have trouble maintaining weight or muscle may benefit most from paying attention to these shifts. Younger adults and people who are not concerned about muscle loss in later life are less directly affected by these specific findings. Anyone with a medical condition that affects appetite, digestion, or kidney function should talk with a doctor or dietitian before making major diet changes.
Changes in eating habits can influence how people feel and function within a few weeks, but measurable changes in muscle size or strength usually take several months of consistent nutrition and activity. Because this study looked at changes across seasons, the time frame was roughly several months. Individual results will vary, and noticeable muscle benefits from improved nutrition typically take at least 8 to 12 weeks to appear.
Frequently Asked Questions
Do older adults eat less in summer than in winter?
A 2026 study of 31 older adults in a care facility in Türkiye found that energy and carbohydrate intake were lower in summer. Men showed the clearest drop, and intakes of zinc, selenium, and omega-3 fats also declined during the warmer months.
Can seasonal changes in diet affect muscle strength in seniors?
A small 2026 study suggests seasonal nutrient changes may be associated with muscle measures, but it cannot prove cause and effect. Calf size increased overall, while grip strength decreased among women. Larger studies are needed to confirm these patterns.
Which nutrients drop in older adults’ diets during summer?
According to research reviewed by Gram, summer intake fell for leucine, omega-3 and omega-6 fats, zinc, and selenium among 31 institutionalized older adults. These nutrients support muscle repair, immune function, and overall health, so consistent intake through the year is worth monitoring.
How can caregivers help older adults keep up protein intake in warmer months?
Adding a protein source to every meal, such as eggs, beans, yogurt, or fish, can help. Nutrient-rich snacks like nuts or cheese may also support energy intake. Tracking meals across seasons can reveal patterns, and a dietitian can tailor the plan.
Want to Apply This Research?
- Log daily energy intake, protein servings, and servings of omega-3-rich foods such as fish, nuts, or seeds for at least 7 days in each season. Also record calf circumference once a month and grip strength once a month using a simple handheld dynamometer if available. Compare monthly averages to spot seasonal patterns.
- Set a reminder to add a protein source to each meal, such as eggs, beans, yogurt, fish, or lean meat. In warmer months, plan one or two extra nutrient-dense snacks, like nuts, cheese, or hummus with whole-grain crackers, to help maintain calorie and mineral intake. Track whether these small additions keep total energy steady.
- Use the app to review seasonal trends over at least one full year, comparing winter and summer totals for calories, protein, and key minerals. Schedule regular check-ins with a healthcare provider to review results, and watch for unintended weight loss, weakness, or changes in appetite. Share the data with a dietitian who can help interpret patterns and adjust the plan.
This article summarizes a small, exploratory study of 31 older adults in one care facility and does not prove that seasonal diet changes cause muscle changes. It is not medical advice. Older adults, caregivers, or anyone concerned about weight, appetite, muscle strength, or nutrition should consult a doctor, registered dietitian, or other qualified health professional before making changes to diet or exercise.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.