In short: no mushroom or adaptogen will make you lose weight. Experiments in mice are interesting, but in human studies the effect has been small or absent, and the evidence is weak. When it comes to weight, what counts is still diet, exercise, sleep and stress.
What is an adaptogen?
The term was introduced in 1947 by the Soviet scientist Nikolai Lazarev. It was used for plants that were supposed to help the body adapt to stress, such as ginseng and rhodiola (Panossian and Wikman 2010). Today, marketing also uses the word for mushrooms such as reishi and lion's mane. In the European Union, adaptogen is not an official term, and the EU register of health claims contains no authorised claims for reishi, lion's mane or any other functional mushroom.
What do animal studies show?
In a study published in 2015, mice on a high-fat diet were given a water extract of reishi mycelium. They gained less weight, and the make-up of their gut microbiota changed (Chang et al. 2015). The study got a lot of attention, but results in mice cannot be transferred directly to people, because the doses, the diet and the metabolism are different.
What do human studies show?
A 2025 meta-analysis pooled 17 randomised trials of reishi with 971 participants. Reishi did not change blood pressure, blood sugar or blood lipids. A small change was found in body mass index, but the authors rated the certainty of the evidence as very low (Jafari et al. 2025). For other mushrooms, there are even fewer human studies on weight loss.
What really matters for your weight?
- Food: meals rich in protein and fibre keep you full for longer.
- Exercise: a daily walk is a good start.
- Sleep: for many people, too little sleep increases appetite and leads to poorer food choices.
- Stress: ongoing stress affects how you eat. A calmer pace to the day helps here.
Where does coffee fit in?
Black coffee is almost calorie-free, at about 2 kcal a cup. The calories come from sugar, syrup, whipped cream and large milky drinks. If you are watching your weight, drink your coffee black or with a little milk. Ra Hygge mushroom coffee is made from organic Arabica, and the mushroom extract does not noticeably change its calorie content.
Where Ra Hygge stands
Our mushrooms are not meant for weight loss. We connect them with a daily ritual and a calmer rhythm: a cup of coffee to sit down with, not to drink on the run. If you want to lose weight, talk to your family doctor or a nutritionist.
Frequently asked questions
Does reishi help you lose weight?
This has not been shown in humans. Experiments in mice are interesting, but in human studies the effect has been small and the evidence very weak.
Does mushroom coffee speed up your metabolism?
Caffeine raises your metabolism slightly for a short time, as any coffee does. The effect is small and does not replace diet and exercise.
Can adaptogens be taken with medication?
If you take any medication, ask your doctor or pharmacist before using mushroom products.
Sources
- Chang CJ, Lin CS, Lu CC et al. Ganoderma lucidum reduces obesity in mice by modulating the composition of the gut microbiota. Nat Commun 2015;6:7489.
- Jafari A et al. The nutritional significance of Ganoderma lucidum on human health: a GRADE-assessed systematic review and meta-analysis of clinical trials. Food Sci Nutr 2025;13(6):e70423.
- Panossian A, Wikman G. Effects of adaptogens on the central nervous system and the molecular mechanisms associated with their stress-protective activity. Pharmaceuticals 2010;3(1):188-224.