Garcinia cambogia and weight loss
There are various claims regarding Garcinia cambogia extract in reviews by both medical experts and online users. One of the most popular of these is the effect that Garcinia cambogia extract may have in causing weight loss. The section that follows investigates these claims…
Obesity is a rising epidemic in many countries. The condition increases the risk of a number of complications such as cardiovascular disease, hypertension (high blood pressure), diabetes mellitus and certain cancers3.
Metabolic complications arise due to obesity-causing derangements (imbalances) in glucose and lipid (organic compounds that are derived from fatty acids) homeostasis. Homeostasis refers to the stable condition of the body as it maintains an equilibrium or balance within its internal environment, regardless of external environmental changes.
Although there are several pharmacological options available for the treatment of obesity and its associated complications, there is a considerable amount of interest in natural options, and as a result, a number of experts have begun to investigate the effects of plants and their anti-obesity properties. ‘Anti-obesity’ refers to the promotion of the loss of excess body fat.
In today’s weight-conscious society, even those who are not classified as clinically obese often want to lose a few pounds and are interested in finding a more natural means to do so. This is where Garcinia cambogia comes in.
Garcinia cambogia is thought to influence weight loss due to the active organic compound hydroxycitric acid (HCA) which is found in the rind of the fruit.
HCA exhibits anti-obesity effects including the suppression of appetite which leads to reduced food intake while preventing the accumulation of fat in the body through regulating serotonin levels which play a role in triggering the feeling of fullness after eating, also known as satiety.
HCA may also increase fat oxidation and decrease de novo lipogenesis (DNL)1, the synthesis of fatty acids that is responsible for converting excess carbohydrates into lipids for storage as fat, by inhibiting the key enzyme involved in this process. This enzyme is known as ATP-citrate-lyase, which is required for the production of acetyl-coenzyme A. Acetyl-coenzyme A plays a vital role in fatty acid, cholesterol and triglycerides syntheses (i.e. the production of these compounds in the body).
**My Med Memo - De novo lipogenesis (DNL) refers to a highly regulated and complex metabolic pathway wherein excess carbohydrates in the body are converted into fatty acids (lipids) for storage in the adipose tissues (i.e. as fat). When this function is decreased, less fat accumulates.
Moving onto studies where experts examined whether Garcinia cambogia supplementation led to weight loss in rats, two studies conducted4,5 showed some positive results. The first study4, conducted in 2001, involved 24 male rats that were fed restrictive diets for a period of ten days, after which they were given access to one of four diets varying in fat and carbohydrate content for a further 10 days, all while being supplemented with HCA.
The study proved HCA’s ability to inhibit the enzyme ATP-citrate-lyase, blocking the effects of lipogenesis (fat production), inducing satiety and reducing weight regain after a weight loss of 10 to 15 percent was recorded in the rodent test subjects. The findings also showed results in increased energy expenditure, which refers to the rate at which calories are burned when at rest.
The second study5, which took place in 2004 as a follow-up to the 2001 study also involved male rats, and was built on the initial findings of its predecessor. In addition to supporting the suppressive effects of HCA on body fat and weight regain, as well as increased energy expenditure, the findings also showed that HCA served to improve glucose tolerance in the animal model. This evidence may contribute to claims surrounding the anti-diabetic effects of Garcinia cambogia. Those who are diabetic have issues with blood sugar levels due to their bodies struggling to transport and utilise glucose in the blood as a result of poor insulin usage or production in the pancreas. (More on this in the section on Garcinia cambogia and diabetes).
There is one major setback to the above findings, this being that the studies, which showed promising results were performed on rats, thus limiting this research in its application to the effects of Garcinia cambogia on humans.
This serious limitation creates an issue as de novo lipogenesis, the main target of Garcinia cambogia, or more specifically, HCA, occurs at a much higher rate in rats than humans. In fact, another study found that the rate at which fatty acid synthesis (the creation of fatty acids) takes place in humans was roughly five times lower in comparison to rats6. This means that even though HCA can reduce DNL and the resulting fat accumulation, it does not make as significant a difference in humans as it does in rats.
Additional studies also show limited results in humans in comparison to those conducted on rats. One of these studies7 involved 86 overweight human participants who were given two grams of Garcinia cambogia extract for ten weeks. This supplementation failed to result in weight loss or any significant changes in body fat percentage.
Another8 systemic review that took place in 2011 further examined the efficacy of Garcinia cambogia extract (hydroxycitric acid (HCA)) as an agent for weight reduction, using data from RCTs (randomised clinical trials). The study concluded that Garcinia cambogia extract may lead to short-term weight loss. However, this finding is limited based on the size of the trials reviewed and the accuracy of the methodologies employed, thus the clinical relevance was deemed uncertain as more rigorous and long-term trials need to be conducted in the future to further prove these marginal weight loss effects.
The Journal of the American Medical Association published a study9 involving a total of 135 participants who were given either a placebo or active hydroxycitric acid (HCA) over a period of 12 weeks. At the end of the study, the weight loss results between the two groups showed no significant differences in the estimated percentage of body fat mass lost.
As previously mentioned, the weight loss effect of Garcinia cambogia (and its active ingredient hydroxycitric acid (HCA)) is, in part, due to increased satiety that is experienced when ingesting Garcinia cambogia extract. This mechanism was first seen in rats and further studies have researched it in humans. The effects of HCA on appetite suppression through increased satiety were explored in a study10 involving 89 mildly overweight women. The participants had to undergo strict diets, with 42 of the women ingesting 400mg capsules of Garcinia cambogia before meals for a total dose of 2.4 grams a day. The other participants were given placebos. Body composition and weight were assessed regularly. At the end of the 12 weeks, it was concluded that no HCA effects on the group’s appetite variables were noted. Thus, the claims of the effect of increased satiety due to the ingestion of HCA that were noted in animal models were not supported in this human trial.
The verdict on Garcinia cambogia and weight loss
Although Garcinia cambogia, or more specifically, HCA does seem to show some promise with regard to weight loss through reduced food intake and body fat gain by regulating the serotonin levels that are related to satiety (feeling satisfied and full after eating), decreased de novo lipogenesis and increased fat oxidation in rats, the evidence of these findings in humans is significantly limited and cannot be considered of clinical relevance at this time.
Until further research involving larger groups of human participants conducted over a longer period of time can take place, it might be wise to hold back on spending your hard-earned money on so-called ‘weight-loss wonders’ like Garcinia cambogia extract.
Garcinia cambogia and diabetes
Diabetes, also known as diabetes mellitus is a disease that occurs when the body does not produce or respond to the hormone insulin efficiently, this results in the abnormal metabolism of carbohydrates which elevates blood glucose levels above what is considered normal.
When we eat carbohydrate-rich food, the sugars and starches are turned into glucose, known as blood glucose when it enters the bloodstream, or blood sugar, this is then used for energy by the cells to function. The pancreas creates the hormone insulin, this aids in transporting glucose and allows it to enter the cells, effectively acting as a key to the doorway of the cells.
When someone has diabetes, their body will either not produce enough insulin or not utilise the hormone effectively. This causes glucose to accumulate in the blood which can result in a number of health complications such as vision changes, an increased risk of infections developing as the body does not heal as quickly, heart disease or kidney failure.
Garcinia cambogia when used as a supplementation in rats to study the effects of the plant on glucose metabolism (i.e. the way that the body utilises glucose), showed promising results11 in improving the use of glucose in the body. Human trials conducted set out to prove this theory and the effect of hydroxycitric acid (HCA) found in Garcinia cambogia in promoting glucose absorption in healthy individuals compared to those with type 2 diabetes.
**My Med Memo – Type 2 diabetes refers to a condition wherein either the pancreas does not produce enough insulin to regulate the movement of glucose into the cells or the body is insulin-resistant, meaning that it does not use insulin correctly. Type 1 diabetes on the other hand, refers to the inability of the pancreas to produce sufficient insulin (if any at all).
The randomised controlled trial12 involved two groups, one made up of twelve healthy individuals and the other eight patients with type 2 diabetes. Both groups received an infusion of 2800mg of HCA in water over a period of 60 minutes. This was followed by 60 grams of glucose infused over two hours. Blood samples were taken frequently.
The results of the study stated that the healthy individuals who were exposed to HCA showed a slight reduction in the presence of glucose in the blood, known as glycaemia and glucagon (a hormone that works with insulin in regulating glucose levels in the body, glucagon raises the concentration of glucose in the bloodstream). However, no effect was seen on insulin or glucose absorption. HCA did not have any effect on glycemia in those with type 2 diabetes.
The verdict on Garcinia cambogia and diabetes
The results of the studies done on humans and the effect of Garcinia cambogia on diabetes are not currently very encouraging, however, further large-scaled studies will need to be performed for more accurate and conclusive results to be determined. Until then, it is not recommended that those with diabetes use Garcinia cambogia to treat their condition.
Garcinia cambogia and bowel conditions (anti-inflammatory properties)
Crohn’s disease, inflammatory bowel disease (IBD) and ulcerative colitis are all chronic diseases of the intestines that are thought to result from the impairment of mucosal immunology, this is the immune system response that occurs in the mucosal membranes of the intestines.
The use of Garcinia cambogia for treating bowel diseases has attracted a large amount of interest due to the plant containing bowel-specific pharmacological properties. Xanthones contained within the plant are powerful antioxidants that are thought to provide gastroprotective effects due to their ability to reduce pain and inflammation.
**My Med Memo – Antioxidants inhibit oxidisation which prevents cell damage.
In a study13 performed in 2009, a research team investigated the anti-inflammatory effect of Garcinia cambogia in rats with colitis. The results from the study showed that the supplementation of Garcinia in colitic rats led to a significant improvement in the symptoms of colitis and damaged caused by it and as such, the plant could potentially provide a new means of treatment for bowel conditions and inflammation.
The verdict on Garcinia cambogia and bowel conditions
The main reason for the success of Garcinia cambogia in proving to be a possible means of treatment for inflammatory bowel conditions is due to the plant containing xanthones which inhibit the catalysts or enzymes of inflammation. However, human trials on the success of Garcinia cambogia in reducing inflammation are limited, this makes the findings partial and restrictive to animal models only.
Garcinia cambogia and other uses
- Heart disease and cholesterol - A very small study14 involving overweight women who were given Garcinia cambogia extract for a period of 60 days showed that the triglyceride levels of the participants dropped by nearly one-third compared to a placebo group. Triglyceride levels are indicative of a kind of fat in the blood, high levels of triglycerides may raise a person’s risk of heart disease. However, the participant’s high-density lipoprotein (HDL), known as the bad cholesterol and low-density lipoprotein (LDL), known as the good cholesterol levels, total cholesterol and body weight remained unchanged.
- Other uses – Studies15 done on Garcinia cambogia when investigating the effects of the plant on other health conditions such as rheumatoid arthritis, cancer, parasites (i.e. worms) and liver disease noted that certain properties of the fruit may help in combatting these conditions. However, these findings are limited and require additional research involving large human trials conducted over a longer period of time, as is the case with a number of claims regarding Garcinia cambogia.
The beneficial properties of Garcinia are thought to be a result of the presence of xanthones and benzophenones, together with amino acids and organic acids (HCA) as all of these components may contribute to the health effects noted due to the supplementation of various species of Garcinia that have been studied.
These individual active agents are explained below:
- Xanthones – Numerous studies16 have shown that xanthones possess anti-oxidant, anti-proliferative (preventing of the spread of cells, particularly malignant cells into surrounding tissues), anti-carcinogenic (inhibiting the development of cancer) and anti-inflammatory properties.
However, the efficacy of these claims needs to be further investigated. - Benzophenones – Studies17 have shown that benzophenones have inhibitory effects against cancerous tumours.
- Amino acids – Amino acids are essential building blocks in the body that aid in the synthesis of cell creation, enzymes, hormones, metabolic pathways, mental stabilisation and neurotransmitters. These are involved in a number of functions in the body and are derived from certain substances and the food we ingest.
- HCA – Also known as hydroxycitric acid, HCA works through suppressing appetite by increasing serotonin levels. A study18 involving rats investigated the effects of HCA on serotonin and found that HCA prevented the reuptake of serotonin in the brain, this is similar to the effect of SSRIs (selective serotonin reuptake inhibitors), which are commonly used anti-depressants.
Serotonin is a natural appetite suppressant as it is a powerful chemical in the brain that is able to curb cravings and allow for one to feel satisfied, even if their stomach is not full.
HCA also prevents fat accumulation by blocking the key enzyme involved in the production of fat in the body.
- Xanthones – Numerous studies16 have shown that xanthones possess anti-oxidant, anti-proliferative (preventing of the spread of cells, particularly malignant cells into surrounding tissues), anti-carcinogenic (inhibiting the development of cancer) and anti-inflammatory properties.
References
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