How much protein does a client on a GLP-1 medication need?

Why protein needs more attention on these drugs

GLP-1 medications such as semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) can substantially reduce appetite and food intake. As with other forms of substantial weight loss, some of the weight lost during GLP-1 therapy can come from lean tissue as well as fat. As overall food intake falls, protein intake can fall too, making adequate protein particularly important when trying to preserve lean mass during weight loss.

In 2025, the American College of Lifestyle Medicine, the American Society for Nutrition, the Obesity Medicine Association and The Obesity Society published a joint advisory on nutrition during GLP-1 therapy. It sets out eight priorities, and one of them is adequate protein intake with strength training to help preserve lean mass. Nutrient-dense food, managing gut side effects and preventing micronutrient shortfalls sit alongside it.

Setting the number

The advisory discusses protein intakes of around 1.2–1.6 g/kg/day during active weight loss, but the body weight used in that calculation matters. As body fat increases, applying the target directly to total body weight can produce an unnecessarily high protein target. Alternative approaches include adjusted body weight, goal or reference weight, or lean mass where reliable body-composition data are available. There is no single universally accepted method, so use an approach appropriate to the individual and the guidance or protocol you are following.

Client: 110 kg, goal weight 85 kg

On total weight:  110 × 1.2 to 1.6  = 132 to 176 g a day
On goal weight:    85 × 1.2 to 1.6  = 102 to 136 g a day

Using the hypothetical goal weight produces a target of 102–136 g/day, compared with 132–176 g/day using actual body weight. This illustrates how the choice of body weight can substantially change the calculated target in a client with obesity. The final target should be individualised rather than automatically choosing one of these figures.

How to work out protein needs compares the different methods in more detail.

Then assess what the client is currently eating. If their intake is well below the target, increase it progressively in a way they can tolerate rather than expecting an immediate jump to the final target.

Making the target eatable

The target is the easy part. The hard part can be achieving it when appetite is reduced, so focus on making protein intake manageable within the amount the client is able to eat.

• Prioritise protein at meals. When appetite is limited, encourage clients to eat the protein-rich part of the meal before filling up on lower-protein foods.
• Smaller, more frequent meals. When appetite is low, spreading protein across smaller meals and snacks may be more manageable than relying on a few large meals.
• Soft and liquid options when needed. Greek yoghurt, cottage cheese, eggs, milk, soups with lentils or chicken, and protein shakes may be easier to tolerate when appetite is particularly low or nausea is present.
• Fibre and fluids alongside. Constipation is a common gastrointestinal side effect of GLP-1 therapy, so adequate fluid and fibre-rich foods such as vegetables, fruit, oats and legumes remain important. When appetite is limited, plan meals carefully so that both protein and fibre needs can be addressed without making portions unmanageable.
• Strength training. Adequate protein should be combined with resistance exercise to support the preservation of muscle and physical function during weight loss. Aim to incorporate resistance training regularly where appropriate to the client's health, ability and medical guidance.

Working within your scope

Medication decisions remain with the client's prescriber. Where a client has a medical condition that affects protein or energy requirements, nutrition targets should be set in accordance with appropriate clinical guidance and within the practitioner's scope of practice. This is particularly important in chronic kidney disease, where protein requirements depend on disease stage and treatment, and in people with diabetes whose medications may require adjustment as food intake and body weight change.

Refer the client back to their medical team (prescriber) if they are unable to maintain adequate food or fluid intake, experience persistent vomiting, or develop concerning symptoms such as severe or persistent abdominal pain. Your role is to provide nutrition and behaviour-change support within your professional scope, while medication management and investigation of adverse symptoms remain with the medical team.