Does yohimbine help burn fat?

Short answer

No worthwhile effect. It did pull fat into the blood on an empty stomach, but body fat dropped only in two 3-week trials of 20 people each, and nothing changed in a 6-month trial (47 people). Reported side effects were often a racing heart, anxiety and high blood pressure.

Does yohimbine help burn fat?
'More fat breakdown → less body fat' — does this formula hold?
Yohimbine comes from the bark of an African tree and shows up often in fat-burner supplements. The pitch is that it releases a brake on fat breakdown. We checked whether body fat actually goes down.
It does pull fat into the blood
But only on an empty stomach; a meal wiped it out
Taken on an empty stomach, yohimbine raised fatty acids in the blood, and more so during exercise. Taken after a meal, the effect vanished completely. Noradrenaline, a chemical that revs up the nervous system, rose 40-50%.
Two 3-week trials showed fat loss
Body fat went from 9.3% to 7.1%
20 people trained for 3 weeks while taking yohimbine or a fake pill. In the yohimbine group body fat fell from 9.3% to 7.1%, with no change in body weight or muscle. In a trial of 20 people on a 1,000 kcal diet, 3-week weight loss was 3.55 kg vs 2.21 kg.
But in a 6-month trial
Weight, body fat and belly fat all stayed the same
47 people were randomly given yohimbine or a fake pill for 6 months (33 finished). Body weight, body fat, and fat distribution measured by CT scan showed no difference from the fake pill. Only the short 3-week trials found an effect.
Side effect reports were common and serious
Racing heart 43%, anxiety 33%, high blood pressure 25%
Over 7 years, a California poison center logged 238 yohimbine side-effect cases: stomach upset 46%, racing heart 43%, anxiety or agitation 33%, and high blood pressure 25%. The rate of serious outcomes was 5.81 times the average for other substances. 2 deaths from acute poisoning have also been reported.
Labels didn't match the bottle
Only 2 of 49 products listed dose and side effects correctly
An analysis of 49 yohimbine supplements sold in the US found the yohimbine in 1 serving ranged from 0 to 12.1 mg. Of the 11 products that listed an amount, the real content was 23-147% of the label. Only 2 products (4.1%) gave both an accurate amount and side-effect warnings.
Bottom line: not something to take for fat loss
An effect only in 3-week trials, none at 6 months, clear side effects
Yohimbine pulled fat into the blood on an empty stomach, but body fat dropped only in 2 trials of 20 people each, lasting 3 weeks. The 6-month trial found no change. With racing heart, anxiety and high blood pressure often reported and product doses all over the place, read it as an ingredient with no reason to use for weight loss.