This study aims to investigate the compliance of high-energy, low-volume oral nutritional supplements (ONS) compared to equivalent high-energy standard ONS (control) in participants at risk of malnutrition.

The use of high-calorie, high-protein ONS is recommended in patients with malnutrition or who are at risk of malnutrition-related disease. However, compliance with ONS is a key feature to improve the patient's nutritional status. Since compliance with ONS could be influenced by the energy density and the volume of the nutritional supplement used, a higher energy density and lower volume ONS could provide similar energy to the standard ONS for the requirements of this population.

This study has been designed as an open-label randomized crossover study with nutritional intervention with the aim to compare the patient's compliance, defined as the percentage of energy consumed with respect to that prescribed, with a high-energy content, low volume ONS versus a standard high calorie and volume ONS, over an 8-weeks follow-up period. As secondary objectives, the study aims to describe the gastrointestinal tolerance and satisfaction of the study ONS, to establish the factors that may affect compliance with the ONS and to compare the cost associated with product wastage in both ONS.

The study population will consist of patients aged ≥ 18 years, distributed into three groups according to their diagnosis: oncological patients, surgical patients, and other patients, all of them malnourished or at risk of malnutrition according to Subjective Global Assessment (SGA), and requiring the use of an ONS. Participants will be randomly allocated to receive either:

Group A: A high energy, low volume ONS (2.4kcal/ml; 125ml) in addition to the diet for 28 days. Participants will then receive the equivalent standard ONS (2.0kcal/ml, 200ml) as control ad libitum in addition to diet for 7 days, or:

Group B. A standard ONS (2.0 kcal/ml, 200ml) as control in addition to the diet for 28 days. Participants will then receive the high energy, low volume equivalent ONS (2.4kcal/ml; 125ml) for 28 days.

Inclusion Criteria:

• Patients ≥ 18 years
• Patients who are in one of the following clinical situations: oncological patients who did not undergo surgery during the month prior to inclusion, including head and neck, esophagus, stomach, pancreas, or colon cancer; surgical patients who underwent surgery less than one month, including all types of surgical processes; and other non-surgical patients diagnosed with benign esophageal stricture, chronic radiation enteritis, and non-oncological maxillofacial pathology, cystic fibrosis, human immunodeficiency virus (HIV), malabsorption syndrome , ulcerative colitis, Crohn's disease, fistula, intestinal pseudo-obstruction, chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), or who were undergone to scheduled major surgery or transplantation within a period of no less than 2 months until inclusion.
• Patients with malnutrition or at risk of malnutrition according to Subjective Global Assessment (SGA).
• Patients with a high energy requirement that require 2 bottles/day of an ONS (≥2kcal/ml), for a minimum period of 8 weeks
• Patients who have not received ONS during the month prior to their inclusion. Surgical patients may have received ONS prior to the study in accordance with the guidelines of the institution.
• Patients who voluntarily agree to participate in the study and give their signed consent for participation.

Exclusion Criteria:

• Patients suffering from any of the following clinical disorders: chronic kidney insufficiency or diabetes.
• Patients requiring enteral tube feeding or parenteral nutrition.
• Patients suffering from an allergy or intolerance to the product ingredients.
• Patients scheduled for surgery during the study period.
• Patients who, in the opinion of the treating physician, are unable to adhere to the protocol instructions, including inability of the patient/caregiver to use the study eCRF, and to remain in the study during all the follow-up.