Key takeaways
- There is no good evidence that any supplement burns meaningful fat during sleep.
- Ashwagandha has modest evidence for stress and sleep, but rare cases of liver injury have been reported.
- Concentrated green tea extract can harm the liver at high doses.
The overnight fat-burning claim
Your body does burn energy during sleep, but it is a fixed baseline that no supplement has been shown to raise meaningfully. Weight change still comes down to your overall calorie balance, which you can estimate with the real TDEE finder.
Ashwagandha
Randomized trials of standardized root extracts report modest improvements in stress scores and cortisol, and a small trial in people with insomnia reported better sleep measures. Reviewers still describe the research as limited by size and short duration. Case reports and a case series from Iceland and the United States describe liver injury linked to ashwagandha products, usually recovering after stopping, but sometimes severe.
L-theanine
This amino acid from tea is generally well tolerated. A small trial in healthy adults found improvements in some stress-related measures and sleep quality after several weeks. Effects are mild.
Green tea extract (EGCG)
Concentrated catechin supplements, particularly at around 800 mg of EGCG a day or more, are linked to liver injury in safety reviews, and the risk seems higher on an empty stomach. This is a different risk from drinking tea.
What else to know
Lemon balm and saffron have small bodies of research, mainly on mood and stress. Black pepper extract added to supplements can increase the absorption of some compounds and drugs, which is a reason to check with a pharmacist if you take medication. If you want better sleep, see our sleep calculator first.
A product to consider
Night Mega Burner
Per the seller’s page, the formula includes N-acetyl tyrosine, L-theanine, ashwagandha KSM-66, green tea extract (40% EGCG), lemon balm, saffron, black pepper extract, vitamin B6 and magnesium.
- Several ingredients, such as theanine and magnesium, are relaxing and well tolerated.
Consult your doctor before use, especially if you are pregnant or breastfeeding, have a medical condition or take medication. Stop and see a doctor if you notice yellow skin or eyes, dark urine or severe stomach pain. This product is not intended to diagnose, treat, cure or prevent any disease.
Try the related tools
Sleep calculator · Supplement stack checker · Real TDEE finder
Sources
- Lopresti AL et al. An investigation into the stress-relieving and pharmacological actions of an ashwagandha extract: a randomized, double-blind, placebo-controlled study. Medicine (Baltimore) 2019. Find on PubMed
- Langade D et al. Efficacy and safety of ashwagandha root extract in insomnia and anxiety. Cureus 2019. Find on PubMed
- Björnsson HK et al. Ashwagandha-induced liver injury: a case series from Iceland and the US Drug-Induced Liver Injury Network. Liver Int 2020. Find on PubMed
- Hidese S et al. Effects of L-theanine administration on stress-related symptoms and cognitive functions in healthy adults. Nutrients 2019. Find on PubMed
- EFSA Panel on Food Additives and Nutrient Sources. Scientific opinion on the safety of green tea catechins. EFSA Journal 2018. Find on PubMed
Links open a PubMed search for each paper so you can read the abstract and full citation. Always check the original study.