Managing Reduced Food Intake and Preventing Dehydration
You need to drink 1.5-2.0 liters of fluids daily from a wide variety of beverages according to your preferences—not just plain water—and this should be done through frequent, scheduled drinking throughout the day rather than waiting until you feel thirsty. 1
Immediate Hydration Strategy
Daily Fluid Goals
- Women should consume 2.0 L/day total from all sources (beverages and food), with beverages representing 70-80% of this intake 1
- Men should consume 2.5 L/day total from all sources, with beverages representing 70-80% of this intake 1
- The minimum recommended intake is 1.5 L of liquids per day to maintain adequate hydration 2
What to Drink
You do not need to drink plain water to stay hydrated—this is a common myth that should be dispelled. 2 Hydrating beverages include:
- Water (plain, sparkling, or flavored) 2
- Hot or cold tea and coffee (coffee does not cause dehydration) 2, 1
- Milk and milky drinks 2
- Fruit juices 2
- Soups 2
- Sports drinks and soft drinks 2
- Smoothies 2
- Beer and lager (up to 4% alcohol can be hydrating if you have no medical contraindications) 2, 1
Choose beverages based on your personal preferences, as this significantly increases the likelihood you'll drink enough. 2 Milky drinks, fruit juices, and smoothies provide additional nutritional benefits when food intake is reduced 2, 1
How to Drink Effectively
Structured Drinking Schedule
Do not wait until you feel thirsty to drink—thirst sensation decreases with age and is an unreliable indicator of hydration needs. 1 Instead:
- Drink fluids frequently throughout the day on a schedule (every 3-4 hours at minimum) 2
- Keep beverages physically accessible at all times 2, 1
- Offer yourself a variety of different drinks throughout the day 2, 1
Behavioral Strategies
- Do not restrict fluids due to fear of needing the bathroom—this voluntary restriction is a common cause of dehydration 2, 1
- Social contact is a key trigger for drinking, so try to drink with others when possible 2
- If you have memory problems that cause you to forget to drink, set alarms or reminders 2, 1
When to Increase Fluid Intake
Increase your fluid intake by 500-1000 mL/day above baseline during: 1, 3
Warning Signs Requiring Medical Attention
Seek prompt medical consultation if you experience: 2
- Persistent nausea or vomiting that prevents fluid intake 2
- Inability to keep down liquids for more than a few hours 2
- Signs of severe dehydration: reduced urine output, dizziness, confusion, rapid heartbeat 3
Special Considerations for Reduced Food Intake
Nutritional Fluids
When not eating much, prioritize beverages with nutritional content: 2
- Milky drinks provide protein and calories 2
- Fruit juices and smoothies provide carbohydrates and vitamins 2
- High-calorie fortified drinks can help maintain energy intake 2
Carbohydrate Needs During Illness
If you're ill and not eating, consume 150-200 grams of carbohydrate daily (45-50 grams every 3-4 hours) to prevent metabolic complications. 2 This can come from:
Electrolyte Replacement
Include sodium-containing fluids to prevent depletion of intravascular volume: 2
Common Pitfalls to Avoid
- Do not assume you'll drink when thirsty—thirst sensation is unreliable, especially in older adults 1
- Do not rely solely on plain water—variety increases intake and some beverages provide additional nutrition 2, 1
- Do not separate liquids from solid foods unless medically necessary—this behavioral restriction can reduce total fluid intake 2
- Do not ignore social isolation—drinking alone reduces intake; try to drink with others when possible 2, 1
Monitoring Your Hydration
You should monitor for signs of dehydration, especially when food intake is reduced: 1
- Urine output and color (dark urine suggests dehydration) 3
- Body weight changes 1
- Complaints of thirst 3
If reduced food intake persists for more than 2-3 weeks, consider thiamin supplementation to prevent neurological complications. 2