Bitter orange is a herb made from the bitter orange tree and is often used in weight-loss supplements.
The research suggests that bitter orange can help with weight loss, however it is often cautioned with warnings outlining the health dangers of taking this supplement.
Bitter Orange & Synephrine
Bitter orange is used for a variety of conditions other than weight loss, including stomach ailments and also fungal skin conditions such as ringworm and athletes’ foot.
Bitter Orange contains Synephrine, similar to the banned substance Ephedra, which can cause high blood pressure and an increased heart rate, especially if used in sports nutrition products where bitter orange is often mixed with caffeine and other supplement ingredients.
What is Synephrine
Synephrine is stimulant that increases your body’s metabolic rate and therefore energy expenditure. Studies have shown that taking Synephrine alone can help increase the resting metabolic rate and burn up to 65 calories in just over an hour 
And the reason why this ingredient is often added to compounds containing caffeine is because Synephrine (bitter orange) and caffeine together can help burn more fat together 
How does Synephrine (bitter orange) help with weight loss?
To understand how bitter orange (synephrine) helps with weight loss, we need to understand something a little deeper about fat cells.
Fat cells have two receptors:
- Alpha-2 receptors
- Beta-2 receptors
Alpha-2 receptors are the “bad receptors” that hinder fat burning whereas beta-2 receptors are good that help with mobilising fat burning.
Stubborn fat regions contain more alpha-2 receptors than beta-2 receptors, which makes it harder for this region to lose fat (think belly fat).
Both fat receptor cells are regulated by “catecholamines” which is a chemical molecule that binds with fat-receptors and releases stored energy for your body to burn as part of its metabolic process. However, some fat cells contain more alpha-2 receptors which are more resistant to mobilisation by catecholamines.
Synephrine has been suggested to block alpha-receptors in fat cells, which can aid in mobilising fat cells  and make more regions with fat more receptive to the catecholamines.
But what is a catecholamine and how is it produced?
Catecholamines are hormones made by your adrenal glands (such as dopamine, epinephrine and norepinephrine)  and are sent to your blood stream when you are under stress.
And this is key – your body is put under stress when you work out and begins to produce catecholamines – particularly during hardcore HIIT (High Intensity Interval Training) exercises.
This is why bitter orange is found in many pre-workouts and fat burners – to help your body burn fat before and after working out.
Side effects of bitter orange and synephrine
As with all supplements, there is a notable amount of content outlining the negatives of bitter orange – particularly due to its association with the banned substance – ephedra.
Ephedra was considered to have adverse health effects such as chest pains (by stimulating the heart), anxiety, high blood pressure and kidney issues.
Some studies indicate bitter orange may have similar health effects such as:
- High blood pressure,
- Heart issues such as heart disease or irregular heartbeat
While these negatives cannot be dismissed, particularly if you have an underlying health condition, bitter orange extract can be taken in safe dosages and if used properly, help with your weight loss goals.
Bitter orange extract contains Synephrine, which helps you lose weight primarily inhibiting alpha-2 receptors on fat cells, making your fat cells more likely to activate and enter your blood stream for energy when you work out
As usual, the effectiveness of taking supplements is only brought about as a final cursor to a healthy diet, focused exercise plan and then supplementation.