Researchers studied 122 heart failure patients to understand if hidden fluid buildup in the body is connected to not eating enough healthy food. They found that patients with early-stage fluid buildup (detected using special ultrasound and body composition tests) were eating significantly fewer calories and less protein than those without this problem. These patients were also eating more carbohydrates and less fiber. The study suggests that checking what heart failure patients eat might help doctors catch and treat fluid buildup before it becomes serious.

The Quick Take

  • What they studied: Whether hidden fluid buildup in heart failure patients is connected to eating too little food and not getting enough protein and calories
  • Who participated: 122 heart failure patients visiting an outpatient clinic in Mexico between April 2023 and January 2025. These were people managing their heart failure without being hospitalized.
  • Key finding: Patients with hidden fluid buildup ate about 380 fewer calories per day and got only 0.84 grams of protein per kilogram of body weight compared to 1.44 grams in those without fluid buildup. They were 10 times more likely to have inadequate food intake.
  • What it means for you: If you have heart failure, your doctor may want to check both your nutrition and for hidden fluid buildup. Eating enough protein and calories might help prevent or reduce this problem, though more research is needed to confirm this.

The Research Details

This was a cross-sectional study, which means researchers looked at a group of people at one point in time rather than following them over months or years. Researchers recruited 122 heart failure patients from a specialized clinic and measured two things: hidden fluid buildup in their bodies and what they were eating.

To detect hidden fluid buildup, doctors used two methods. The first was a special ultrasound called VExUS that looks for excess fluid in the veins. The second was bioelectrical impedance vector analysis (BIVA), which sends a harmless electrical signal through the body to measure fluid levels and body composition.

For nutrition assessment, patients reported everything they ate over three separate 24-hour periods. Researchers then compared their actual intake to recommended amounts: 25-30 calories per kilogram of body weight for energy and 1.2 grams of protein per kilogram of body weight.

This research approach is important because it uses objective medical measurements (ultrasound and bioelectrical analysis) rather than just asking patients how they feel. This makes the findings more reliable. By studying people at one point in time, researchers could quickly identify patterns between poor nutrition and hidden fluid buildup, which could lead to better screening methods for heart failure patients.

The study’s strengths include using multiple reliable methods to detect fluid buildup and collecting dietary information over three separate days (which gives a more accurate picture than a single day). The main limitation is that this is a snapshot in time, so we can’t prove that poor eating causes fluid buildup or vice versa. The study was conducted at one specialized clinic, so results may not apply to all heart failure patients. Additionally, the study didn’t control for all factors that might affect eating, such as medications or depression.

What the Results Show

Patients with hidden fluid buildup ate significantly less food overall. They consumed an average of 1,098 calories per day compared to 1,478 calories in those without fluid buildup—a difference of about 380 calories. This is important because heart failure patients need adequate calories to maintain muscle and strength.

Protein intake was also much lower in the fluid buildup group: 0.84 grams per kilogram of body weight versus 1.44 grams in the other group. Protein is especially important for heart failure patients because it helps maintain heart muscle and overall body function.

Interestingly, patients with fluid buildup ate a higher percentage of their calories from carbohydrates (64.3% versus 49.1%) and consumed much less fiber, especially soluble fiber (0.53 grams versus 3.01 grams). Soluble fiber is the type found in oats, beans, and apples that helps with digestion and heart health.

When researchers looked at the numbers mathematically, patients with hidden fluid buildup were 10 times more likely to have inadequate food intake compared to those without fluid buildup.

The study identified lack of appetite as an independent risk factor for not eating enough. Patients who reported poor appetite were 11 times more likely to have insufficient calorie and protein intake. This is important because it suggests that appetite loss might be an early warning sign that doctors should address in heart failure patients. The pattern of eating more carbohydrates and less fiber in the fluid buildup group is also noteworthy, as this dietary pattern is not ideal for heart health.

Previous research has suggested a connection between poor nutrition and fluid buildup in heart failure, but studies on this topic have been limited. This research provides more concrete evidence using modern measurement tools. The findings align with what doctors know about heart failure: poor nutrition can worsen the condition, and fluid buildup can reduce appetite, creating a harmful cycle. However, this study is one of the first to measure both hidden fluid buildup and detailed dietary intake in the same group of patients.

This study has several important limitations. First, because it’s a snapshot in time, we can’t determine whether poor eating causes fluid buildup or if fluid buildup causes poor eating—likely both happen. Second, the study included only 122 patients from one clinic in Mexico, so results may not apply to heart failure patients in other countries or settings. Third, researchers didn’t measure other factors that might affect eating, such as depression, medications, or access to food. Finally, the study relied on patients remembering what they ate, which can be inaccurate. The confidence intervals for some findings are quite wide, meaning there’s more uncertainty in those results.

The Bottom Line

Based on this research (moderate confidence): Heart failure patients should work with their doctor and a registered dietitian to ensure they’re eating enough calories and protein daily. Doctors may consider screening for hidden fluid buildup in patients who report poor appetite or inadequate food intake. Patients should aim for at least 1.2 grams of protein per kilogram of body weight and 25-30 calories per kilogram of body weight, adjusted for individual needs. Increasing fiber intake, particularly soluble fiber from sources like oats and beans, may be beneficial.

This research is most relevant for people with heart failure, their caregivers, cardiologists, and registered dietitians who work with heart failure patients. It’s particularly important for those experiencing poor appetite or weight loss. People without heart failure don’t need to apply these specific findings, though the general principle of adequate nutrition is important for everyone.

Improvements in appetite and food intake might be noticed within 2-4 weeks of working with a dietitian and addressing underlying causes. Changes in fluid levels and body composition typically take 4-8 weeks to become apparent. Long-term benefits in heart function and symptom management may take several months to develop.

Want to Apply This Research?

  • Track daily protein intake (in grams) and total calories consumed, comparing actual intake to your personalized goal (typically 1.2 g/kg protein and 25-30 kcal/kg). Also track appetite level on a 1-10 scale and any signs of fluid buildup like weight gain, swelling, or shortness of breath.
  • Set a daily protein target based on your body weight and use the app to log meals that meet this goal. If appetite is poor, focus on smaller, more frequent meals with protein-rich foods like eggs, Greek yogurt, fish, or beans. Use the app to receive reminders to eat regular meals and snacks.
  • Weekly review of average protein and calorie intake compared to goals. Monthly tracking of body weight and any symptoms of fluid buildup. Share monthly reports with your healthcare team to adjust nutrition plans as needed. Alert your doctor if appetite suddenly decreases or if you notice rapid weight gain.

This research suggests an association between hidden fluid buildup and poor nutrition in heart failure patients, but does not prove cause and effect. These findings should not replace professional medical advice. If you have heart failure, consult your cardiologist and registered dietitian before making significant dietary changes. This study was conducted in a specific population and may not apply to all heart failure patients. Always discuss nutritional concerns and any new symptoms with your healthcare provider, especially if you experience sudden weight gain, increased shortness of breath, or swelling in your legs or abdomen.