Ashwagandha against stress and obesity: New RCT study 2026 shows impressive results
Table of contents at a glance
- Study overview - The most important facts
- Key findings in detail
- Why stress makes you fat - The cortisol vicious cycle
- How does Ashwagandha affect stress and weight?
- Safety profile and side effects
- Ashwagandha vs. other adaptogens - An honest comparison
- Correct dosage and administration
- What you should pay attention to when it comes to Ashwagandha
- Frequently Asked Questions
- Sources
1. Study overview - The most important facts
Ashwagandha ( Withania somnifera ) is among the most intensively researched adaptogens worldwide. However, most previous studies only lasted eight weeks and focused exclusively on stress reduction. This new study goes further: For the first time, it investigated the combination of stress reduction and weight management over a full 24-week period.
Definition: Ashwagandha (Withania somnifera) is an adaptogenic herb used in Ayurvedic medicine. As an adaptogen, it can help the body adapt to stress by modulating the hypothalamic-pituitary-adrenal (HPA) axis and regulating cortisol production. Clinical studies have shown positive effects on stress levels, sleep quality, and body composition.
Study: Pakhale K, Pakhale R, Srivathsan M, Langade J, Langade D.
Title: Efficacy and safety of Ashwagandha (Withania somnifera) root extract on stress and weight management in adults.
Journal: Journal of Medical Life, 2025; 18(12):1140-1154
Design: Prospective, randomized, double-blind, placebo-controlled
Participants: 100 adults (19-65 years), BMI 25-39.9 kg/m2
Duration: 24 weeks
Intervention: 300 mg KSM-66 Ashwagandha root extract, twice daily
PMID: 41635453
Of particular note: The study used KSM-66 Ashwagandha, a standardized root extract with more than 5% withanolides. Participants were instructed to maintain their usual eating and exercise habits throughout the study – there were no additional diets or exercise programs.
2. Key findings in detail
The results of this study are remarkably clear. Here are the key figures at a glance:
(Ashwagandha group)
after 24 weeks
(PSS score)
| parameter | Ashwagandha (n=45) | Placebo (n=46) | significance |
|---|---|---|---|
| Body weight (week 24) | -8.46 +/- 3.86 kg | -2.41 +/- 2.07 kg | P < 0.0001 |
| BMI (Week 24) | -3.31 +/- 1.57 kg/m2 | -0.93 +/- 0.79 kg/m2 | P < 0.0001 |
| Stress level (PSS score) | -6.16 points | -1.43 points | P < 0.001 |
| Quality of life (SF-12) | +9.38 points | +2.54 points | P < 0.001 |
| Cravings (FCQ-T) | -21.24 points | -8.28 points | P < 0.0001 |
| Serum cortisol | -5.02 mcg/dL | -2.55 mcg/dL | P = 0.005 |
The effect sizes were consistently large (Cohen's d > 0.8), which is rare in dietary supplement research. Particularly impressive: The ashwagandha group lost an average of over 6 kg more than the placebo group – and this without diet or additional exercise.
At Ayuba, we have worked extensively with Ashwagandha in recent years and have received feedback from numerous customers confirming precisely this synergy: less stress, fewer evening cravings, and better sleep. This study now provides the scientific basis for what many of our customers have already reported.
3. Why stress makes you fat - The cortisol vicious cycle
To understand why ashwagandha can help with weight loss, one must first understand the connection between chronic stress and weight gain. It is no coincidence that stressed people are more likely to reach for sweets and fast food.
The mechanism works as follows: Chronic stress permanently activates the so-called HPA axis (hypothalamic-pituitary-adrenal axis). This leads to a persistently elevated cortisol level. Cortisol, in turn, has several direct effects on body weight.
6 ways chronic stress leads to weight gain:
- Increased appetite: Cortisol directly stimulates the hunger center in the hypothalamus and increases the craving for high-calorie food.
- Visceral fat storage: Glucocorticoids specifically promote fat accumulation in the abdominal area - the most metabolically dangerous fat.
- Cravings for comfort food: Under stress, the body prefers sugary and fatty foods because these activate the reward system in the short term.
- Poor sleep: Elevated cortisol disrupts the sleep-wake cycle, and lack of sleep in turn increases ghrelin production (hunger hormone).
- Insulin resistance: Chronically elevated cortisol levels can impair insulin sensitivity, which promotes fat storage.
- Reduced energy consumption: Under constant stress, the body switches to a conservation mode, which can lower the basal metabolic rate.
This is precisely where Ashwagandha comes in: by regulating the HPA axis and lowering cortisol levels, it breaks this vicious cycle at its root - quite literally.
4. How does Ashwagandha affect stress and weight?
Ashwagandha is a so-called adaptogen. This means it can help the body adapt to various stressors without triggering a specific pharmacological effect. The active ingredients are the withanolides – a group of steroidal lactones that are primarily concentrated in the root.
According to current research, the three main mechanisms of action are:
1. HPA axis regulation: Ashwagandha modulates the activity of the hypothalamic-pituitary-adrenal (HPA) axis. This leads to a measurable reduction in cortisol levels, as this study impressively demonstrates (from 13.91 to 8.90 mcg/dL after 24 weeks).
2. Neurotransmitter balance: Preclinical studies show that ashwagandha positively influences serotonin and dopamine levels and can increase BDNF (brain-derived neurotrophic factor) levels. This explains the observed improvement in mood and the reduction of emotional eating.
3. Metabolism optimization: There is evidence that ashwagandha can support energy metabolism, so that the body is more likely to burn fat than store it. Furthermore, beneficial effects on HbA1c levels and total cholesterol were observed in week 12 of the study.
"The synergistic interaction of stress modulation, metabolic optimization, and antioxidant activity underlies Ashwagandha's potential for healthy weight management." - Pakhale et al., 2025
5. Safety profile and side effects
A crucial aspect of this study is the comprehensive safety assessment over 24 weeks. This is significantly longer than most previous Ashwagandha studies, which typically lasted only 8-12 weeks.
The results are reassuring: Of 50 participants in the Ashwagandha group, only 7 reported mild side effects - and in the placebo group, there were 6. All side effects were mild and disappeared on their own.
| Side effect | Ashwagandha | placebo |
|---|---|---|
| nausea | 3 (6.0%) | 3 (6.0%) |
| Abdominal pain | 2 (4.0%) | 2 (4.0%) |
| Tiredness/Drowsiness | 2 (4.0%) | 1 (2.0%) |
| In total | 7 (14.0%) | 6 (12.0%) |
Of particular importance: All laboratory values – including liver and kidney function, blood count, lipid profile, and thyroid levels – remained within normal limits throughout the entire study period. There were no serious side effects. This supports the safety of long-term use of ashwagandha root extract.
6. Ashwagandha vs. other adaptogens - An honest comparison
Ashwagandha isn't the only adaptogen on the market. Here's an honest comparison with other popular options, specifically when it comes to combining stress reduction and weight management:
| Adaptogen | Stress reduction | Weight management | Study status (2026) |
|---|---|---|---|
| Ashwagandha (KSM-66) | Very well documented | Well documented (this study) | Stark (multiple RCTs) |
| Rhodiola Rosea | Well-filled | Weakly documented | Moderate |
| Ginseng (Panax) | Moderately occupied | Some hints | Moderate |
| Holy basil (Tulsi) | Moderately occupied | Hardly any data | Weak |
| Reishi mushroom | Some hints | Hardly any data | Weak |
What sets ashwagandha apart from other adaptogens is the quality and depth of the research – especially this new 24-week study. While there is also good data on stress reduction for rhodiola and ginseng, there are hardly any controlled studies that have examined their effect on body weight.
Frankly, Rhodiola can offer benefits for acute stress and mental fatigue that Ashwagandha doesn't. Choosing the right adaptogen always depends on your individual goals. However, for the combination of stress reduction, improved sleep, and weight management, Ashwagandha currently has the strongest evidence base.
7. Correct dosage and intake
The study used a clear dosage: 300 mg of standardized ashwagandha root extract (min. 5% withanolides), twice daily - once after breakfast and once after dinner.
Dosage recommendations based on the available studies:
For stress reduction: 300 mg twice daily (600 mg total daily dose). This is the dosage used and clinically proven in this study.
Time of intake: Take with meals (after breakfast and after dinner) with a glass of water. Taking it with food may improve tolerability.
How long should you take it? The study shows that the effects built up continuously over 24 weeks. Significant differences were measurable after just 4 weeks, but the strongest results were seen after 24 weeks. So patience pays off.
Magnesium bisglycinate: 200-300 mg (elemental magnesium)
Dosage: Approximately 60 minutes before bedtime.
Effect: Calms the central nervous system and improves the onset of sleep
Vitamin B complex: 1 capsule (high dose, including B6, B12 and folic acid) Zinc (as bisglycinate or picolinate): 15–25 mg
Dosage: 300 mg Ashwagandha + B-complex in the morning with breakfast; 300 mg Ashwagandha + zinc in the evening with dinner.
Effect: Stabilizes energy levels throughout the day and supports hormone synthesis
L-Theanine: 200 mg (works synergistically with Ashwagandha against restlessness) Magnesium L-Threonate: 1,000–2,000 mg (corresponds to approx. 75–150 mg elemental magnesium)
Dosage: * During the day: 300 mg Ashwagandha + 200 mg L-Theanine (for focus without tremors).
In the evening: 300–600 mg Ashwagandha + Magnesium L-Threonate (for maximum neuronal regeneration).
Effect: Optimizes cognitive function and ensures a measurably deeper regeneration phase (REM sleep)
8. What you should pay attention to when it comes to Ashwagandha
Not every ashwagandha product on the market lives up to its promises. The differences in quality are enormous, and you should be especially critical in Germany.
The 5 most important quality criteria:
1. Root extract, not leaf extract: The study used only root extract. Many inexpensive products include leaves, which have a different withanolide profile and are less well-researched.
2. Standardization to withanolides: At least 5% withanolides (per HPLC) should be listed on the label. This guarantees a consistent active ingredient concentration.
3. Solvent-free extraction: KSM-66 (the extract used in the study) uses a water-based extraction without alcohol or chemical solvents - this is the gold standard.
4. Purity testing and certification: GMP certification, HACCP standards, and ideally third-party laboratory analyses. German consumers rightly demand pharmacy-quality products and transparent manufacturing processes.
5. Production in certified facilities: Germany has stricter standards than many other countries. Look for products manufactured in GMP-certified facilities.
At Ayuba Nutrition, we operate according to GMP and HACCP standards because we firmly believe that purity and quality are uncompromising. Every batch is tested for heavy metals, pesticides, and microbiological contaminants. This is more complex and expensive, but it's the only way to offer products we can truly stand behind.
9. Frequently Asked Questions
Sources
- Pakhale K, Pakhale R, Srivathsan M, Langade J, Langade D. Efficacy and safety of Ashwagandha (Withania somnifera) root extract on stress and weight management in adults: a prospective, randomized, double-blind, placebo-controlled study. J Med Life . 2025;18(12):1140-1154. PubMed
- Chandrasekhar K, Kapoor J, Anishetty S. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults. Indian J Psychol Med . 2012;34(3):255-262. PubMed
- Choudhary D, Bhattacharyya S, Joshi K. Body weight management in adults under chronic stress through treatment with Ashwagandha root extract. J Evid Based Complementary Altern Med . 2017;22(1):96-106. PubMed
- Sinha R, Jastreboff AM. Stress as a common risk factor for obesity and addiction. Biol Psychiatry . 2013;73(9):827-835. PubMed
- Chrousos GP. Stress and disorders of the stress system. Nat Rev Endocrinol . 2009;5(7):374-381. PubMed
- Mastorakos G, Zapanti E. The hypothalamic-pituitary-adrenal axis in the neuroendocrine regulation of food intake and obesity. Nutr Neurosci . 2004;7(5-6):271-280. PubMed
0 comments