Creatine while losing weight on GLP-1: does it help preserve muscle?

With Mounjaro, Wegovy and co., the kilos often drop off quickly. But you lose not only fat, also part of your fat-free mass – that is, muscle, water and organ tissue. You can read more in our guide on muscle loss on GLP-1.

The two most important levers against muscle loss are well known: strength training and enough protein. Creatine is no substitute for these; at most it can be a small add-on – and only if you actually train.

Important up front: there are no studies so far that have looked at creatine specifically in people on tirzepatide or semaglutide. Everything you read here comes from studies with strength training – mostly in older adults or athletes.

A 2017 meta-analysis (Open Access Journal of Sports Medicine) evaluated 22 randomised studies with 721 older adults (mean age 57–70 years). Result: those who took creatine in addition to strength training gained on average about 1.4 kg more fat-free mass than the comparison group. Strength in chest and leg presses also rose somewhat more.

The Deutsches Ärzteblatt (a German medical journal) summarises the evidence similarly in 2026: in people aged 55 and over, strength training plus creatine was “consistently more effective than strength training alone”.

Whether the effect is just as large in the steep calorie deficit on a weight-loss injection is unknown. Honestly: it is plausible, but not proven.

In the EU, creatine monohydrate is an authorised ingredient in food supplements – not a medicine. Studies and the specialist literature mostly use 3–5 g of creatine per day (Deutsches Ärzteblatt, March 2026).

According to the Verbraucherzentrale (as of April 2026), EFSA considers 3 g per day harmless for healthy adults, and in sport up to 5 g of creatine monohydrate daily is regarded as safe. High-dose “loading phases” are not needed for preserving muscle.

This is general information, not a personal recommendation. Whether creatine suits you is best clarified with your doctor – especially if you take medication.

Creatine is stored in the muscles and draws water into the muscle cells in the process. The Verbraucherzentrale points out: the weight gain comes from water in the muscle cells, not from fat.

For you this means: when you start creatine, the scale may stall or even rise slightly in the first few weeks, even though you keep losing fat. That is no sign that your weight-loss injection has stopped working. We explain why the scale sometimes goes up in scale going up despite the weight-loss injection.

BIA scales (body fat scales) can also show different values because of the changed water balance. So compare trends over several weeks instead, for example with our Tracker, and also measure your waist and strength numbers.

Creatine raises the creatinine level in the blood. Creatinine is a lab value used to estimate kidney function. According to the Verbraucherzentrale, the rise on creatine does not mean kidney damage – but it can distort lab results. So tell them before every blood test that you take creatine.

On top of that: on GLP-1, many people drink too little, and diarrhoea or vomiting can dehydrate you further. Enough fluid is therefore doubly important – see drinking on a weight-loss injection. Pregnant or breastfeeding women and children should not take creatine without medical advice.

When buying: creatine monohydrate is the best-studied form. Other, often more expensive forms are much less well studied. Look for a tested monohydrate with independent lab analysis, for example listed on the Kölner Liste (Cologne List), and avoid unknown suppliers without proof of testing.

In the EU, exactly two health claims are authorised for creatine (each at 3 g per day):

• “Creatine increases physical performance in successive bursts of short-term, high intensity exercise.”
• For adults over 55: daily creatine consumption can enhance the effect of resistance training on muscle strength – only in combination with regular resistance training.

• Claims such as “burns fat”, “protects against muscle loss while dieting” or “provides energy for the muscles” are not authorised.
• Creatine replaces neither protein nor training – see nutrition on a weight-loss injection.

If, after talking to your doctor’s practice, you want to try creatine, a few simple rules help you keep track:

• First establish training and protein reliably, then add creatine – not the other way round.
• Start only one new supplement at a time so you can attribute effects and side effects.
• Note the start date so you can correctly interpret a water-related rise on the scale.
• Record your strength numbers in training – they often say more about muscle preservation than the scale.
• With gastrointestinal complaints, which are common on GLP-1 anyway, better pause and get it checked.

After a few weeks you can take an honest look: are you training regularly, do you tolerate it well, and are your lab values normal? If not, there is no reason to continue. Other substances and their evidence are covered in the biohacking overview.