When Appetite Disappears on a GLP-1 Medicine: Under-Eating, Protein-First Small Meals, Eating-Disorder Red Flags and Where the Coach's Role Ends

Our earlier pieces covered food noise and muscle, and coming off or maintaining after GLP-1 treatment. This one is about the opposite of overeating: eating too little.

GLP-1 and GLP-1/GIP medicines such as semaglutide (Wegovy) and tirzepatide (Zepbound) reduce appetite and slow stomach emptying. The FDA-approved prescribing information for Wegovy and Zepbound lists nausea, vomiting, diarrhoea and constipation among common side effects, and warns about acute kidney injury related to dehydration from GI side effects.

Put those together and some clients feel full after a few bites, or feel queasy at the thought of food. Others like the feeling of not eating and start to skip meals on purpose. Both patterns are worth noticing.

A meaningful share of weight lost on GLP-1-based therapies can be lean tissue (Neeland et al., 2024). A 2025 joint advisory from ACLM, ASN, OMA and TOS (Mozaffarian et al., 2025) recommends that people on these medicines get adequate protein, prioritise nutrient-dense foods, and do resistance training, with support from clinicians and dietitians. Very low intake makes all three harder.

Clients may also notice fatigue, light-headedness, hair shedding, constipation or feeling cold. These have many possible causes and are for the prescriber to assess, not the coach.

1. Make eating regular, even when hunger isn't. Agree a simple rhythm, such as three small meals and one or two snacks at set times, so meals don't depend on appetite. Phone reminders help.

2. Protein first, in small portions. Suggest starting each meal with the protein part: eggs, Greek yogurt, tofu, fish, chicken, beans or lentils. Soft and cold foods are often easier when nauseated. The exact protein target is for the clinician or a registered dietitian to set.

3. Liquids count, but don't replace meals by default. Milk, kefir, soups and smoothies can help on low-appetite days. If a client is relying on shakes for most of their intake, that's a conversation for their prescriber or a dietitian.

4. Fluids through the day. Sip regularly rather than drinking large amounts at once, especially in heat or after exercise. Dizziness, very dark urine or not passing much urine are reasons to contact the prescriber.

5. Keep the strength sessions. The Physical Activity Guidelines recommend muscle-strengthening activity on two or more days a week. Schedule sessions after a meal or snack, not on an empty stomach.

6. Track behaviours, not just the scale. Log meals eaten, protein at each meal, fluids and strength sessions. That gives the client something useful to share with their prescriber.

Appetite suppression can overlap with disordered eating, and some clients may have a history of an eating disorder. The National Institute of Mental Health describes eating disorders as serious, treatable illnesses that can affect people of any age, gender or body size. Coaches are not trained to diagnose or treat them.

Refer, kindly and promptly, if a client:

• says they are frightened to eat, or feels guilty after eating anything
• is pushing to lose weight faster, skipping meals deliberately, or wants to "stay on the medicine to keep not eating"
• is making themselves vomit, using laxatives or exercising to "make up" for food
• has a history of an eating disorder and is now restricting
• is losing weight much faster than their prescriber planned.

And refer urgently (prescriber the same day, urgent care or 911) for fainting, chest pain, a racing heartbeat, severe or persistent vomiting, severe stomach pain, or signs of dehydration.

Client: "I'm just not hungry. I had a coffee and half a sandwich yesterday. Isn't that the point?"

Coach: "Less hunger can help, but eating too little makes it harder to keep muscle and energy. Could we try three small meals at set times, starting with protein, and track it this week? I'd also like you to tell your prescriber how little you're eating. They may want to review things."

Client: "Honestly, I like not eating. I feel in control."

Coach: "Thank you for telling me. That feeling is something I want you to talk through with someone trained in this, like your doctor or an eating-disorder specialist. I'll keep coaching your training, and I'm glad to help you find support."

The coach never suggests lowering, skipping or stopping a dose. Those are prescriber decisions. Our Level 4 GI, alcohol and eating-out scripts and coaching alongside a prescriber modules go further.

1. "How many meals or snacks did you eat on most days?"
2. "Did each one include some protein?"
3. "Any dizziness, vomiting, constipation or feeling faint?"
4. "How did strength sessions go?"
5. "How do you feel about food this week?" (Listen for fear, guilt or restriction.)
6. "Anything we should share with your prescriber?"

Health coaching is generally not a state-licensed profession in the US, but medical nutrition therapy, prescribing and eating-disorder treatment belong to licensed professionals. Use the NBHWC scope of practice as a reference, and keep a referral list that includes the client's prescriber, a registered dietitian and local eating-disorder services. The NIDDK explains that obesity treatment includes medical care and lifestyle changes together; the coach supports the lifestyle side.

Start free at Level 1. Level 3 (US$300): GLP-1 basics, food noise and lifestyle. Level 4 (US$500): coaching alongside the prescriber, GI and eating-out scripts. Level 5 (US$500): hard cases, including new starts. Education and referral, never prescribing or selling. We do not guarantee income or client numbers.

This article is education, not medical advice. It does not recommend any medicine or dose. If you're worried about your eating, talk to your doctor or an eating-disorder specialist.