Also known as: Chlorogenic acid, CGA, Green coffee extract, Svetol, GCA
Fat MetabolismEmerging evidence
Unroasted coffee beans, standardised for chlorogenic acid. Sold hard on the back of research that turned out to be seriously flawed, which is a story worth knowing before you buy any of it.
Typical dose
200.0–400.0 mg per day
Before meals; check total caffeine across your other supplements
What it is
Green coffee beans are simply coffee beans that have not been roasted. Roasting develops the flavour compounds we recognise as coffee but destroys much of the chlorogenic acid, which is why the unroasted bean is used for extracts.
Chlorogenic acid is a polyphenol, not an acid in any dietary sense, and extracts are standardised to it, commonly at 45 to 50 per cent.
Green coffee extract still contains caffeine, typically less than roasted coffee but enough to matter. If a product does not declare its caffeine content, you are stacking an unknown amount on top of whatever else you take, which is worth checking before adding it to a pre-workout routine.
How it works
Chlorogenic acid inhibits an enzyme involved in releasing glucose from the liver, and appears to slow carbohydrate absorption in the gut. Both would moderate the blood sugar rise after a meal.
There is also research interest in effects on fat metabolism signalling, though this is largely preclinical.
The caffeine content contributes its own well-documented thermogenic effect. Any product containing meaningful caffeine will produce caffeine effects, and disentangling those from anything chlorogenic acid does is a genuine difficulty in interpreting the research.
What the evidence shows
Green coffee extract became a mass-market product on the back of a small trial reporting striking weight loss. That trial was subsequently retracted, and the company that funded it was penalised by regulators over the claims built on it. This is not a minor footnote — it is the origin of the entire category.
Systematic reviews of the remaining literature have reported small effects on body weight, generally under two kilograms, while consistently noting that the underlying trials are small, short and often of poor methodological quality.
Research on blood sugar markers and blood pressure is somewhat more encouraging and arguably the more defensible reason to take it. The fat loss case rests on evidence that has not survived scrutiny well.
Dosing
Common doses are 200-400 mg of extract, two or three times daily, taken before meals. Trials have used a range of doses with no clear dose-response established.
Dose against chlorogenic acid content rather than extract weight, and check the caffeine figure. A product supplying meaningful caffeine alongside your pre-workout and coffee adds up quickly.
Be realistic about expectations. If the goal is fat loss, the evidence does not support paying much for this. If you want the blood sugar effects, that case is stronger, and taking it before carbohydrate-containing meals makes mechanistic sense.
At a glance
Common forms
45-50% chlorogenic acid extract, Svetol, Decaffeinated green coffee extract, Within thermogenic blends
Half-life / duration
Chlorogenic acid metabolites clear within hours
Timing
Before meals; check total caffeine across your other supplements
Competition status
Permitted — not on the WADA Prohibited List
Category
Fat Metabolism
Safety and side effects
Generally well tolerated. Digestive upset, headache and, where caffeine content is meaningful, jitteriness and disturbed sleep are the reported effects.
The caffeine content is the main practical consideration and the easiest thing to overlook, since people do not think of a fat loss capsule as a caffeine source. Count it toward your daily total.
Because it may lower blood sugar, take care if yours is being managed. Speak to your doctor before use if you take regular medication.
Who should avoid it
Count the caffeine content toward your daily total, and take care combining with other stimulants. Take care if your blood sugar or blood pressure is being managed. Speak to your doctor before use if you take regular medication. Not established at supplemental doses in pregnancy or breastfeeding.
This entry is provided for information only. Food supplements should not be used as a substitute for a varied and balanced diet and a healthy lifestyle. Consult a qualified healthcare professional before use if you are pregnant, breastfeeding, taking medication or under medical supervision.
