When the scales start moving in the right direction, it is tempting to treat every lost kilogram as good news. After all, that is what you're using the medication for.
Weight, however, is not made up of just one single part.
When you lose weight, your body may lose fat, water and some lean tissue. That means the more useful question is not simply, "Am I losing weight?" it's more along the lines of: "What kind of weight am I losing?"
Table of Contents
1. A Quick Reminder: What Is Foundayo?
2. Can Foundayo Cause Muscle Loss?
3. What Did the Foundayo Study Find?
4. Why Does Preserving Muscle Matter?
5. How Can You Help Protect Your Muscles?
5.2. Give Your Muscles Something to Do
5.3. Avoid Turning "Eating Less" Into "Hardly Eating"
6. When Should You Ask for Help?
7. So, Can You Lose Muscle With Foundayo?
8. Sources
A Quick Reminder: What Is Foundayo?
Foundayo is the brand name for orforglipron, a prescription-only GLP-1 medicine developed by Eli Lilly. It was authorised in the UK in August 2026 for weight management and insufficiently controlled type 2 diabetes.
The tablet is taken once daily and works on areas of the brain involved in appetite. It may help you feel fuller, experience less hunger and manage food cravings, making a reduced-calorie diet easier to follow.
That can support weight loss. However, the body does not always take all its lost weight neatly from the fat cupboard.
Can Foundayo Cause Muscle Loss?
Some loss of lean mass can happen while taking Foundayo, just as it can with other forms of weight loss.
This does not mean Foundayo directly attacks your muscles. When you lose a meaningful amount of weight, particularly if you eat substantially less, the body may use both stored fat and lean tissue.
"Lean mass" and "muscle" are also not exactly the same thing. Lean mass measurements include muscle, but they can also include water, organs and other non-fat tissue. They should not be read as a perfect measurement of muscle alone.
What Did the Foundayo Study Find?
In a body-composition analysis from the ATTAIN-1 trial, 171 of the study's 3,127 participants underwent DXA scans. These scans estimated changes in fat and lean mass over 72 weeks.
The results suggest that participants lost considerably more fat mass than lean mass.
However, this was a small, voluntary subgroup. The results were also pooled across different doses and were not adjusted for multiple statistical comparisons. They give us useful information, but they are not a promise of what will happen to every person taking Foundayo.
Your muscles have not signed the same contract as somebody else's.
Why Does Preserving Muscle Matter?
Muscle supports far more than how strong you feel carrying the shopping.
It plays an important role in:
- Strength and mobility.
- Balance and physical independence.
- Supporting bones and joints.
- Using energy and managing blood glucose.
- Maintaining weight loss over time.
Losing too much muscle may leave you feeling weaker or more tired. This can be particularly important for older adults or people who already have limited mobility.
The goal is therefore not simply to make the number on the scales smaller. It is to support fat loss while preserving as much strength and muscle as reasonably possible.
How Can You Help Protect Your Muscles?
Include Enough Protein
Protein helps your body build and maintain muscle. Good sources include eggs, fish, lean meat, yoghurt, beans, lentils, tofu and other soya-based foods.
Your individual needs may differ, particularly if you have kidney disease or another medical condition. Ask a dietitian or healthcare professional before adopting a high-protein diet or making major dietary changes.
Give Your Muscles Something to Do
Strength-based activity tells your body that its muscles are still required.
This does not have to mean entering a complicated relationship with the heaviest weights in the gym. Chair exercises, resistance bands, body-weight movements and lifting manageable weights can all count.
NHS guidance recommends that adults include muscle-strengthening activity on at least two days each week, where appropriate.
Avoid Turning "Eating Less" Into "Hardly Eating"
Foundayo may reduce your appetite, but your body still needs nutrients.
Regular balanced meals can help you obtain enough protein, vitamins and minerals. If nausea, vomiting or other side effects are making it difficult to eat or drink, contact your prescriber or pharmacist.
A disappearing appetite is not an achievement badge if your nutrition disappears with it.
When Should You Ask for Help?
Speak to your healthcare team if you notice persistent weakness, unusual tiredness, dizziness, difficulty completing normal activities or an ongoing inability to eat enough.
Your prescriber can review your progress, side effects and nutritional intake. Pharmacy Planet's clinical team can also provide appropriate support if Foundayo is prescribed following an assessment.
So, Can You Lose Muscle With Foundayo?
Yes, some lean mass may be lost during Foundayo-supported weight loss. However, the available body-composition data suggest that fat mass decreased substantially more than lean mass in the small group studied.
The aim should not be weight loss at any cost.
Eat well, include suitable strength-based activity and ask for help if your appetite or side effects are making adequate nutrition difficult.
Your scales can report the total.
They cannot tell the whole story.
Sources
- MHRA: UK authorisation of orforglipron for weight management and type 2 diabetes
- The New England Journal of Medicine: Orforglipron, an oral small-molecule GLP-1 receptor agonist for obesity treatment
- Eli Lilly: Foundayo clinical data and ATTAIN-1 body-composition analysis
- Guy's and St Thomas' NHS Foundation Trust: Dietary advice for people taking weight-loss medicines
- NHS: Physical activity guidelines for adults
