Probiotics are among the most popular supplements and are often presented as an aid to weight loss. But what is really true? In this guide you will see how the gut microbiome relates to weight, what studies found and what you can realistically expect.
What probiotics are
Probiotics are live microorganisms that, in adequate amounts, may benefit health. The best known are strains of the genera Lactobacillus and Bifidobacterium. We find them in some fermented foods and in supplements.
Prebiotics are something different: they are fibres, such as inulin, that «feed» the beneficial bacteria of the gut.
Probiotics and weight at a glance
| Question | Answer |
|---|---|
| Do they help with weight loss? | In studies the difference is small, about half a kilo over a few weeks. |
| Does the strain matter? | Yes. Each strain acts differently and results cannot be generalised. |
| What matters most? | Overall diet, fibre, physical activity and sleep. |
| Approved EU claims | No. In the EU there is no approved health claim for probiotics. |
How the microbiome relates to weight
Trillions of microorganisms live in our gut, together called the gut microbiome. They help break down fibre, produce substances such as short-chain fatty acids and interact with metabolism and appetite.
Studies show that the microbiome of people with obesity differs on average from that of people with normal weight, mainly in diversity. But it is not clear what is cause and what is effect: diet changes the microbiome and the microbiome affects metabolism.
What the research shows
A review of 15 clinical trials in people with overweight or obesity, published in Obesity Reviews, found that with probiotics weight fell on average by about 0.6 kg more than with placebo. Body mass index fell by about 0.3 units and body fat percentage slightly.
The trials lasted 3 to 12 weeks, used different strains and several had design flaws. The researchers concluded that the effect is small and that larger, longer-term studies are needed.
In plain words: probiotics are not a «slimming pill». They may make a small contribution, always together with diet and lifestyle.
What applies in the European Union
In the EU, the word «probiotic» itself on a label is considered a health claim, because it implies a benefit. To date no claim for probiotics has been approved, because EFSA did not consider the evidence sufficient. That is why labels often say «friendly bacteria».
6 things worth knowing
- Fibre is the foundation. Pulses, vegetables, fruit, oats and wholegrains feed the beneficial bacteria.
- Variety matters. The more different plant foods you eat during the week, the more diverse your microbiome usually is.
- Fermented foods. Yoghurt, kefir and sauerkraut contain live cultures.
- The strain matters. A result found for one strain does not automatically apply to all.
- Give it time. Studies assessed results over at least several weeks of continuous use.
- Bloating in the first days. It is common and usually passes. If it persists, stop and ask your doctor.
Who should be careful
- People with severely weakened immunity, for example during chemotherapy or after a transplant.
- People who are seriously ill in hospital or have a central venous catheter.
- Pregnant and breastfeeding women and children, who should ask their doctor first.
Friendly bacteria in Active Woman products
Slim Probiotics contains 6 strains of friendly bacteria (Bifidobacterium animalis, B. bifidum, B. longum, Lactobacillus acidophilus, L. casei rhamnosus and Streptococcus thermophilus), a total of 10.2 billion CFU per capsule, together with 100 mg of inulin. The capsule is delayed-release and the dose is 1 capsule a day.
For those who want more fibre, there is also Xtra Fibre & Prebiotics. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle.
Read also
- Probiotics and prebiotics: everything you need to know about the gut
- Glucomannan: what it is and how to use it correctly
- Gut microbiome analysis at our practice
- Online appointment for a personalised nutrition plan
Frequently asked questions
Do probiotics make you lose weight?
Not on their own. In studies the difference was small, about half a kilo over a few weeks.
What time should I take them?
Follow the instructions on the pack. The most important thing is to take them consistently every day.
Do I need probiotics if I eat yoghurt?
Not necessarily. A varied diet with fibre and fermented foods is already a good basis for the gut.
Are they safe?
For healthy adults they are generally considered safe. People with severely weakened immunity should ask their doctor first.
How long should I take them?
Studies on weight lasted up to 12 weeks. Discuss with your dietitian whether you need to continue.
Sources
- Borgeraas H. et al. Effects of probiotics on body weight, body mass index, fat mass and fat percentage in subjects with overweight or obesity: a systematic review and meta-analysis of randomized controlled trials. Obesity Reviews, 2018.
- NutraIngredients. Probiotics backed for weight loss benefits: Meta-analysis, 2017.
- FSAI. Probiotic Health Claims.
- FoodNavigator. Why the EU still restricts «probiotics» claims, 2025.
This article is for information purposes and is not a medical diagnosis, nor does it replace a doctor’s advice.
