Supplement
Ashwagandha (Withania somnifera)
One of the most widely used adaptogens — herbs believed to help the body cope with stress. Ashwagandha has a long history in Ayurvedic medicine. It is now one of the best-selling supplements in the world. The weight evidence is about cutting cortisol and stress-driven eating, not about burning fat directly. If stress and emotional eating add a lot to your weight, the science fits your case better.
Estimated cost
~$15–$35/month for standardised KSM-66 or Sensoril extract
How to take
One or two capsules daily — often taken at night as it can cause drowsiness in some people
In a randomised controlled trial, 52 adults under chronic stress took 600 mg/day of KSM-66 ashwagandha for 8 weeks — body weight fell 3.0% and BMI 2.9%, against 1.5% and 1.4% on placebo.
For context — weight loss from prescription medications:
How it works
The main documented effect of ashwagandha is a drop in cortisol, the body's main stress hormone. Cortisol that stays high for a long time drives fat storage, above all belly fat. It also raises appetite, drives cravings for carbs, and feeds insulin resistance — the body responding poorly to its own insulin. By lowering cortisol, ashwagandha may cut stress-driven eating indirectly. It may also improve sleep quality, which affects weight in its own right, and modestly shift body composition. Its active compounds, the withanolides, appear to act on the HPA axis (hypothalamic-pituitary-adrenal) — the body's stress response system.
What the evidence shows
Cortisol in the blood dropped significantly, meaning by more than chance would explain. Scores for food cravings and emotional eating improved as well. A broader set of trials confirms the cortisol-lowering and stress-reducing effects, including a 27% drop in perceived stress in one trial. The effects on weight and body composition are modest. They are most relevant for people who overeat when stressed. Ashwagandha is not a weight loss drug. It is better understood as a stress-management supplement, with a knock-on effect on weight in people affected by stress.
The trade-off
What this tends to offer:
- Genuine stress and cortisol reduction (well-documented)
- May reduce stress-driven eating and cravings
- Generally well-tolerated
- Affordable (~$15–$35/month)
What this involves:
- Not a direct weight loss supplement
- Benefits limited to people with stress-related overeating
- Should not be used during pregnancy
- May interact with thyroid medication and immunosuppressants
Safety
Well tolerated in short-term studies, which ran up to 3 months. The most common side effects are mild gut (GI) discomfort and drowsiness. Drowsiness can be handy if you take it at night. Rare cases of liver injury have been reported. They are not established as caused by ashwagandha, but they are worth knowing about. Not recommended in pregnancy, as it may cause contractions of the womb. It may interact with thyroid medicines, because it can shift thyroid hormone levels. It may also interact with sedatives, and with drugs that damp down the immune system. People with autoimmune conditions should take care, as ashwagandha may stimulate the immune system.
Community insights
These are personal experiences shared in public online communities — not medical advice.
“Better sleep is often the most noticeable effect. Many people report clearly better sleep quality within 1–2 weeks. Better sleep also helps with weight indirectly.”
“Look for KSM-66 or Sensoril. These are the standardised, patented extracts used in the clinical trials. Plain 'ashwagandha root powder' can vary in how much withanolide it holds.”
“If you take thyroid medication such as levothyroxine, check with your doctor before taking ashwagandha. It can shift thyroid hormone levels.”
Common questions
Written and maintained by one person · Built with agentic AI tools · Every number checked against the cited trial · Not medical advice
In the RCT in chronically stressed adults (Choudhary et al., 600 mg/day KSM-66, 8 weeks), Body weight reduced 3.0% vs 1.5% placebo (P<0.05). BMI reduced 2.9% vs 1.4%. Serum cortisol significantly decreased. Food cravings and emotional eating scores both improved. First study to specifically show ashwagandha reduces food cravings via stress relief.
In the Double-blind RCT, stress and anxiety in adults (KSM-66, 300 mg twice daily), Significant reduction in stress, anxiety, and serum cortisol levels. 29% reduction in perceived stress scores; ~19% reduction in serum cortisol vs placebo. Well tolerated.
After reading this page, most people compare this with other supplements, look at prescription options, or check what they can do today without a prescription.
Next step most people take
Built with agentic AI tools and not a substitute for medical advice
Last reviewed: