Can Total Parenteral Nutrition (TPN) decrease appetite?

Can TPN Decrease Appetite?

Yes, TPN can suppress appetite and reduce food intake, though this effect is not universal and depends on multiple patient-specific factors including age, inflammatory status, and underlying disease.

Evidence for Appetite Suppression

The appetite-suppressing effect of TPN has been documented across multiple studies:

• Animal studies demonstrate that TPN directly reduces voluntary food intake, with precise regulation of daily oral caloric intake observed during parenteral feeding 1, 2
• The mechanism appears to involve changes in peripheral metabolites that may translate into alterations in brain neurotransmitter levels known to decrease food intake 1
• Theories suggest peripheral metabolites act as signals via the liver and hypothalamus for metabolic control of food intake, explaining TPN's anorectic effect 1

Clinical Reality: Variable Patient Response

However, recent clinical evidence challenges the universality of this effect:

• A 2025 study of 102 hospitalized adults receiving PN found that 62.7% actually reported experiencing hunger during PN, contradicting the assumption that parenteral nutrition universally suppresses appetite 3
• Long-term home TPN patients generally report low hunger during most of the day, though those taking small amounts of food orally typically experience moderate hunger before eating 4
• Short-term TPN patients (average 31 days) experienced hunger despite receiving adequate calories for energy balance 4

Factors That Predict Absence of Appetite on TPN

The following factors independently predict lack of hunger during TPN, rather than TPN itself being the primary cause:

• Higher age - older patients are more likely to experience absent appetite 3
• Active inflammation - inflammatory states suppress appetite independent of nutritional route 3
• Metastatic cancer - advanced malignancy is associated with cachexia and appetite loss 3

Impact of Lipid Administration

The role of lipid infusions in appetite suppression remains controversial:

• Early studies suggested prolonged hunger suppression when lipid was added to total nutrient intake 4
• However, a 2025 study found that lipid doses and energy reduction strategies did not affect hunger or satiety 3
• Aversive sensations were frequently associated with lipid infusion but not with non-lipid nutrient infusion 4

Clinical Implications for Transitioning Off TPN

Patients who experience hunger during TPN have significantly better outcomes when transitioning to oral/enteral nutrition:

• Transition success to oral/enteral nutrition was 2.38 times higher (95% CI: 1.59-3.54) in patients who experienced hunger compared to those who did not 3
• When TPN is stopped, some patients show continued suppression of oral intake for a period of time 2

Guideline Perspective on TPN and Appetite

While guidelines do not directly address TPN's effect on appetite, they emphasize:

• The ASCO guideline notes that TPN in cancer patients resulted in higher caloric intake but did not improve body composition or survival, suggesting nutritional delivery does not address underlying appetite mechanisms 5
• For advanced cancer patients, medications like megestrol acetate are recommended to enhance appetite, acknowledging that nutritional support alone may not restore normal eating 5

Bottom Line for Clinical Practice

Do not assume TPN is suppressing your patient's appetite. Instead, evaluate for the true culprits: underlying inflammatory conditions, advanced malignancy, and age-related factors 3. The presence or absence of hunger during TPN is actually a useful prognostic indicator for successful transition to oral feeding 3.