So overall, the weight loss we see in these high-quality studies is very small and mostly without changes in body composition.
The studies included people with different diseases, and most were from the Middle East or the Indian subcontinent. Therefore, we cannot be sure that we would see this effect in people with other health profiles and in other countries. They were also carried out over different periods of time, from two to six months.
The supplements were different, depending on the study. In some, the active ingredient was extracted from cinnamon, in others, powdered cinnamon was used. Doses ranged from 0.36 g to 10 g per day.
They also used two different types of cinnamon, but neither study used supermarket cinnamon.
How could cinnamon cause small amounts of weight loss?
There are several possible mechanisms.
It appears to allow glucose (sugar) in the blood to enter the body’s cells more quickly. This lowers blood glucose levels and can make insulin work more effectively.
It also appears to improve the way we break down fat when we need it for energy.
Finally, it can make us feel full longer by slowing the rate at which food is released from the stomach to the small intestine.
What are the risks?
Cinnamon is generally considered safe when used as a spice in cooking and in foods.
However, in recent months the USA and Australia have issued health alerts about the level of lead and other heavy metals in some cinnamon preparations.
The leader enters as pollutant during growth (from the environment) and at harvest. In some cases, it has been suggested that there may have been intentional contamination.
Some people may have side effects of cinnamon, including gastrointestinal pain and allergic reactions.
One of the active ingredients, coumarin, can be toxic to the liver in some people. This has led the European Food Authority to set a limit of 0.1 mg per kg of body weight.
cassia cinnamon contains up to 1 percent coumarin, and the Ceylon variety contains much less, 0.004 percent. So, for people weighing more than 60 kg, 2 teaspoons (6 g) of cassia cinnamon would exceed the safe limit.
