Loss of Appetite in Japanese People: Causes and Ways to Regain Appetite

1. The Current State of Appetite Loss and Its Severity

• In the United States, 15-30% of the elderly experience appetite loss, leading to significant issues such as weight loss, muscle atrophy, and frailty. Chronic unconscious reduction in food intake can trigger frailty.

• In Japan, a similar trend is accelerating, with reports of eating disorders requiring treatment, particularly among elderly living alone and those in nursing homes.

2. The Mechanism of Appetite: What Influences It

• Appetite is controlled by the coordination of the brain, digestive system, endocrine system, and nervous system. U.S. research is currently unraveling this complex mechanism.

• With aging, basal metabolism decreases, taste and smell decline, and hormonal changes lead to a feeling of fullness after eating only a little.

• Additionally, psychological stress from life events such as retirement or the death of a spouse can affect eating behavior.

3. The Impact of Appetite Loss on Health

• Continuous low food intake leading to weight and muscle loss results in decreased energy, increased risk of falls, and reduced immunity.

• Nutrient deficiencies affect nerve functions, skin, and internal organs, leading to a decline in quality of life (QOL).

4. The Complexity of Causes: Factors Not to Be Overlooked

• Physical factors making eating difficult, such as decreased swallowing function, reduced saliva production, and dental issues.

• Medical conditions like hypothyroidism and cancer, as well as side effects of medications, can also inhibit appetite.

• Differential diagnosis by a physician is crucial.

5. Lifestyle and Dietary Innovations for Improvement

• Small Meals: Consume the necessary energy evenly throughout the day with 3 meals and 3-4 snacks.

• Focus on High Protein: Eat eggs, fish, beans, and dairy products first.

• Use Dips: Add nut spreads, yogurt, or herbs to vegetables and fruits.

• Drink fluids after meals: Avoid large amounts of water during meals.

• Use healthy fats like whole milk products and butter in moderation.

• Enhance flavors with herbs and spices to stimulate appetite.

• As a social factor, increase opportunities to eat together, incorporating conversation and enjoyment.

6. Calorie and Nutritional Balance Settings

• The guideline is 2,200 to 2,400 kcal for men over 50 and about 1,800 kcal for women of the same age group.

• Examples of menus and a weekly meal plan to ensure necessary nutrients (proteins, vitamins, minerals).

7. Be Cautious with Medications and Medical Interventions

• Appetite-enhancing drugs have limited effects and potential side effects, so reviewing lifestyle habits should be the first choice.

• Collaboration with specialized therapists and dietitians for swallowing training and nutritional support is important when necessary.

8. Support Systems and Community Healthcare Initiatives in Japan

• Introducing national model cases such as home nutrition guidance, cooking classes for the elderly, and meal improvement support in day services.

9. Future Research and Challenges

• There are areas of growing interest, such as the new appetite-suppressing hormone "raptin" and its relation to sleep.

• The "Set Point Theory" helps in understanding the mechanisms of weight maintenance and clarifies the biological background of appetite control.

• Enhancing epidemiological surveys and intervention studies within Japan and collaborating with public health are required.

10. Conclusion: Towards a Society that Recaptures the Desire to Eat

Decreased appetite due to aging is not merely a phenomenon of aging but a significant issue affecting healthy life expectancy. Understanding the causes, providing individual support, and improving living environments are essential to support the desire to eat. Comprehensive support through the recovery of the joy and social aspects of eating, rather than mere "nutritional supplementation," will become a new public health strategy in Japan's aging society.

Reference Article

1. Poor appetite? What that can mean and how to get hungry again. Washington Post (Wellness) – June 9, 2025

2. Why you feel less hungry – Washington Post explanatory article. Insights into the physiological mechanisms controlling appetite  

3. Raptin, a sleep‑induced hypothalamic hormone, suppresses appetite and obesity. – Cell Research (2025 report)

4. Set point theory – An overview discussing the biological regulatory mechanisms of weight and appetite