Disease-related malnutrition is common across healthcare settings in the UK and if left untreated, may have severe consequences. One of the strategies commonly used to combat malnutrition is the use of oral nutritional supplements (ONS). However, there is uncertainty about the optimal way of delivering ONS to patients to maximize compliance and nutrient intake.

This randomised study will investigate the effect of different modes of delivery (ad libitum versus instructions on timing/serving volume) of ONS used in addition to the diet on total nutrient intake, compliance, nutritional status and outcome in participants at risk of malnutrition.

Participants will be randomised to receive one of two ONS (high energy or standard) for 4 weeks in addition to food, either taken 'Ad libitum', or according to instruction on what to take and when. The primary outcome measure is nutrient intake. Secondary outcome measures include compliance and acceptability of ONS, appetite, anthropometry, muscle strength, quality of life and gastro-intestinal tolerance.

Inclusion Criteria:

• Male or female
• Age > 18 years
• At risk of malnutrition (medium or high risk of malnutrition with 'Malnutrition Universal Screening Tool', 'MUST' score ≥ 1)
• Competent to provide written informed consent and able to answer questions
• No requirement for tube or parenteral feeding
• Willingness to take part in the study and to follow the study protocol

Exclusion Criteria:

• Requirement for tube or parenteral nutrition
• Participants receiving palliative care
• Participants with chronic renal disease requiring dialysis
• Participants with liver failure
• Participants that are pregnant or lactating
• Participation in other studies