Yohimbe for Fat Loss

Legendary African aphrodisiac might help fat-burning, but risks seem to outweigh its benefits.

Though it’s most widely known as a traditional herbal for sex enhancement, Yohimbe (Pausinystalia johimbe) has also shown some promise as a weight loss supplement. In this area of wellness, Yohimbe is believed to work by:

• Increasing heat generation (thermogenesis) by stimulating sympathetic nervous system
• Boosting the breakdown of fat (lipolysis) by blocking certain receptors found in fat cells
• Raising the blood concentration of fat-burning hormones norepinephrine and epinephrine

Overview

Pausinystalia johimbe, known popularly as yohimbe, is an evergreen tree species found in central and western Africa. The bark of the tree contains the active ingredient yohimbine, which has been used primarily as an aphrodisiac in traditional African medicine.¹

While its effectiveness for sexual issues is supported by numerous studies, Yohimbe is also now being investigated as a potential fat burner. Let’s check out Yohimbe’s possibilities for healthy weight management.

Yohimbe’s Fat-Burning Bio-Activities

The hormones norepinephrine and epinephrine play an important role in the breakdown and storage of fat in the human body. When they bind with alpha-2 adrenoceptor sites found in fat cells, these hormones slow the breakdown of fat. When bound to beta receptors, they seem to have the opposite effect, working to accelerate the breakdown of fat.².

Yohimbine (the active ingredient in Yohimbe) is classified as an alpha-2 antagonist: A substance that inhibits alpha-2 receptors.

• By blocking alpha-2 receptors from binding to norepinephrine and epinephrine, and increasing the amount of these hormones that can bind to beta receptors, yohimbine is believed to promote fat breakdown (lipolysis).

Plus, yohimbine also appears to increase the body’s production of heat (thermogenesis), which may further assist with fat loss. Researchers have attributed this effect to increased stimulation of the sympathetic nervous system.

It is also possible that yohimbine suppresses appetite. Evidence of this benefit was found in rat research, but no human studies have been performed as of yet.³

How does Yohimbe feel?

With the two bio-activities described above, Yohimbe appears to be somewhat effective for fat-burning and weight loss. Judging from existing studies, Yohimbe is a powerful supplement you can feel working: It may result in increased blood pressure and heart rate, and might make you feel “warmer.” These sensations are not necessarily pleasant or healthy, and underscore the risks associated with yohimbe supplementation.

Research

Animal Research

Animal trials of yohimbe have shown mixed results. While it has stimulated weight loss, it also appears to cause some unwanted side effects.

One animal study found that administering 0.25 mg of yohimbine per kg of bodyweight to dogs increased both the breakdown of fat and heat production over a period of at least 4 hours.⁵ Researchers in this study also suggested that:

• The fat-burning effect was attributed to increased stimulation of beta-receptors in fat tissues.
• The increase in heat production was attributed to sympathetic nervous system activation.
• Yohimbine also significantly raised heart rate and blood pressure in the canine subjects.

Another animal study looked at the safety and effects of yohimbine and another similar compound in obese rats. Rats in the yohimbine group were administered 2 mg or 5 mg per kilogram of bodyweight daily for 31 days, and were then evaluated for weight loss benefits and possible side effects.

• The study’s authors suggested that even though Yohimbine was effective for its anorectic (appetite-suppressing) action and promoted weight loss, its negative side effects seemed to outweigh its usefulness.⁶ The researchers further suggested that partial alpha-2 agonist compounds would work better than yohimbine for weight loss.

Human Research

Similar to animal research, human studies of Yohimbe and Yohimbine show mixed results for fat-burning benefits.

Yohimbine shows no effect on men’s fat loss or fat distribution.

In one randomized, double-blind, placebo-controlled study, a group of 47 men (average age 42) were given either high-dose yohimbine groups (peak of 43 mg/day) or placebo daily for a span of six months. Throughout the study, researchers tracked the subjects’ body weight, BMI, body fat, fat distribution and blood cholesterol. 33 of the study subjects completed the study.

• At the end of the study, researchers concluded that “yohimbine had no effect on any variable in comparison with the control group.”⁷

Yohimbine 20 mg may promote fat loss in athletes.

This study looked at the effect of yohimbine on body composition and exercise performance of 20 professional soccer players. Subjects were split into 2 groups for 21 days, one of which received 20 mg yohimbine per day in 2 doses, while the other received a placebo. The athletes continued a strength and conditioning training program during this period.

At the end of the study, researchers found yohimbine brought no significant changes to body mass, muscle mass or exercise performance.

However, researchers found that the yohimbine group experienced a significant drop in body fat percentage – from 9.3% before supplementation to 7.1% after. Researchers also noted that Yohimbine at doses of 40 mg/day did not raise heart rate, increase blood pressure, or induce anxiety. Study subjects did not report any side effects associated with the yohimbine supplement.

• The authors of this study concluded that “supplementation with yohimbine combined with resistance training does not significantly alter the body mass, muscle mass, or performance indicators in professional soccer players.” However, despite its lack of effect on body mass or performance, the researchers suggested that “…Yohimbine supplementation appears to be suitable as a fat loss strategy in elite athletes.”⁸

Yohimbine can evoke dangerous cardiovascular effects in obese individuals.

This study looked at the cardiovascular effects of yohimbine, caffeine, and ephedrine in addition to a 400 kcal/day diet in obese women. The women were broken up into 3 groups of 9 for 10 days. The first group followed the diet and took a placebo; the second group followed the diet and took 2x25mg of ephedrine and 2x200mg of caffeine daily; the third group added 2×5 mg of yohimbine to the previous parameters.

All 3 groups lost roughly the same amount of weight – 3.3kg for group 1, 3.5kg for group 2, and 3.4kg for group 3. Researchers attributed these results to the short duration of the test, and the low-calorie diet distorting the effect of the supplements. While ephedrine and caffeine had no undesirable effects on cardiovascular state in obese patients, the addition of yohimbine appeared to evoke dangerous changes in the cardiovascular system:

• The researchers concluded that “the addition of yohimbine to this regimen [of caffeine and ephedrine] attenuated [weakened] cardiac performance during rest and handgrip and increased cardiac work during dynamic exercise.“⁹

Yohimbine 20 mg daily may help weight loss in obese women. 

In this study, 20 obese women first followed a 1,000 kcal/day for 3 weeks. After this, they were divided into 2 groups of 10: One group followed the diet along with taking 5 mg yohimbine 4x daily for 3 weeks, while the other group followed the diet and took a placebo. At the study’s end, researchers reported that yohimbine had no effect on lipolysis (breakdown of fat) or rate of gastric emptying. However, the yohimbine group was found to have lost 3.55 kg over the course of the study, while the placebo group only lost 2.21 kg.

• The researchers in this study concluded that “Yohimbine significantly increased the mean weight loss in patients on a low-energy diet.”¹⁰

Dosage Notes

• Yohimbe supplements are most commonly presented as a 4:1 extracts with dosages in the 250 mg to 550 mg range.
• Standardized Yohimbe supplements will have a smaller serving size, but may supply more of the bark’s active yohimbine. A typical example would be Yohimbe 100 mg standardized to 3% yohimbine.
• Successful studies seem to suggest dosage of the bark’s active ingredient, yohimbine, should be approximately 0.2mg per kg of bodyweight, which translates to about 15 mg yohimbine daily for an average male.

Side Effects

The most common side effects of yohimbine are elevated heart rate and blood pressure. Other possible side effects include a rapid or irregular heartbeat, irritability, sinus pain, excitation, tremors and sleep problems. Taken orally, yohimbine may cause stomach upset and headaches.

Taking high high doses of yohimbe is a terrible idea that can lead to far more serious complications. People with ulcers, neurological concerns, or pre-existing cardiovascular or kidney health problems should not take yohimbe supplements at all.

Available Forms of Yohimbe

Plain Yohimbe: Ground-up yohimbe bark; cheap, less effective, and rarely used in supplements.

Yohimbe Liquid Extract: These extracts are not typically concentrated, and will often be seen in a 1:1 ratio. A serving will be 20+ drops, supplying 1,000 mg yohimbe extract. Liquid Yohimbe extracts will taste horrible, but may be faster-acting.

Concentrated Yohimbe Extract: As described in Dosage Notes, these extracts are typically presented as 4:1 concentrates. This means that a 250 mg dose is equivalent to 1,000 mg yohimbe bark; 500 mg is equivalent to 2,000 mg yohimbe bark, etc. Keep in mind, even though these extracts are highly concentrated, you’ll have no idea how much active yohimbine is in each dose.

Standardized Yohimbe Extract:  These yohimbe supplements will supply the whole bark, calibrated in a way that supplies an exact level of the bark’s active ingredient, yohimbine. They are often standardized to 2% – 3% yohimbine per capsule.

“Complexed” Yohimbe: Some supplements will combine yohimbe or yohimbine with other nutrients in proprietary blends that are purported to be more effective, but we have seen absolutely no evidence supporting this strategy.

Yohimbine HCl: This supplement form supplies just yohimbe’s active ingredient, yohimbine — so overall serving size will be considerably smaller.