weight loss supplements

Weight Loss Supplements: What Works?

There are many different types of supplements that are purported to promote weight loss. Many of these claims are based on theory rather than robust scientific evidence.

There are many concerns about the short and long-term safety of certain supplements. Whilst in most cases there isn’t a health risk of trying out a supplement to see if it works for you, it can certainly come at a high financial cost. Supplement companies who claim to have the magic pill can charge what they like as they know people will find the money to shift the fat.  In this article I sift through the research to help you decide whether using a supplement to support weight loss is right for you.


Ketone Supplementation:

Ketones are produced by the liver when following a very low carbohydrate diet, putting you in  state of ketosis (not to be confused with keto-acidosis). Ketones are used by the body as a source of fuel. The ketogenic diet has been shown to be a very effective weight loss strategy and is being used more and more as a therapeutic intervention for various chronic conditions (1). Will supplementing ketones, without the carbohydrate restriction produce similar results? There is very limited research on the oral supplementation of ketone esters. The only scientific evidence of their safety and efficacy comes from a trial completed on rats (2). It showed that supplementation is well-tolerated and resulted in decreased blood glucose levels. Decreasing blood glucose levels is a positive step when trying to manage weight. Whilst this is promising, we need to remember that we are rather different to rats.

There is a fair amount of anecdotal evidence that indicates similar positive results. There are many detrimental effects of too many carbohydrates in the diet and my concern is that supplementation alone may not address the actual health risks of obesity. Until we have further evidence on supplementation in humans, I would be hesitant to recommend using ketones, and would only currently consider them to boost the benefits for someone who is active and following a ketogenic or low carbohydrate diet.


Caffeine Supplementation:

Interestingly, I was unable to find any studies on caffeine supplementation for weight loss. Many weight loss supplements contain caffeine, and this is based on the premise that caffeine increases energy expenditure and therefore calories burned. One study found that those who maintained weight loss had a higher consumption of caffeine than the general public (3). Note that this was a study on weight maintenance, not weight loss and was also focused on dietary caffeine rather than supplementation, therefore there are limited conclusions that we can draw from this research. There is lots of research on dietary caffeine, but this is very different to caffeine supplementation. Dietary caffeine is consumed along with antioxidants and trace minerals when consumed as part of coffee, tea and dark chocolate, and it’s these elements that are thought to have many of the significant health benefits.

A side-effect of consuming caffeine is an increase in cortisol levels (4), a stress hormone that has been linked to an increase in central adiposity (fat deposits around the abdomen and internal organs) (5). Therefore, over-consumption of caffeine, particularly in the chronically stressed, may increase weight. This is something that I see frequently with many clients.


Carnitine Supplementation:

Carnitine is an amino acid that is produced in the liver and kidneys and is involved in glucogenesis; the process that converts blood glucose to energy (6). Therefore, carnitine may be involved with the increase in energy expenditure (7) and therefore an increased rate of calorie burning. Carnitine also plays a role in fat metabolism(8). A systematic review of the literature, that included studies with a variety of control groups (carnitine vs no carnitine, carnitine + exercise vs placebo + exercise, carnitine + low calorie diet vs placebo + low calorie diet, and so on) found that carnitine does significantly increase weight loss (9). However, the effectiveness of carnitine did seem to decrease with time. Again, I would only recommend as part of a full body approach.


Omega-3 Supplementation:

There are many reasons why omega-3 is thought to support weight loss. It’s been proven to be beneficial for a whole host of health concerns; cardiovascular disease, rheumatoid arthritis, Alzheimer’s disease, inflammatory bowel disease, asthma, cystic fibrosis, brain health, foetal development, behavioural disorders, depression, and many more (10). Omega-3 is thought to support weight management through various mechanisms such as fat breakdown, conversion of adipose tissue to brown fat, brain-gut adipose tissue axis and most importantly, inflammation-reduction (11).

Research has shown that increased inflammation has been linked to an increase in obesity, specifically through an imbalance of omega 6:omega 3 fatty acids (11). The typical western diet has a high level of omega 6 and low levels of omega 3. This imbalance of fats is inflammatory. Therefore, supplementation with omega 3 fats paired with a reduction of omega 6 fats (primarily found in canola, sunflower and vegetable oils, but also fast-food, grains and grain-fed meat) may promote a more beneficial balance of fats, leading to a reduction in inflammation.

Despite the strong theory and promising research indicating that inflammation increases obesity, studies that have evaluated the use of omega-3 supplements for weight loss have yet to find any significant benefits (12,13). Despite this, I do not hesitate in recommending omega-3 supplementation due to it’s proven safety record and numerous health benefits.


Green Tea Supplementation:

Green tea is another compound that has been shown to increase energy expenditure and fat oxidation (14). Green tea has gained much attention and has been the subject of many research studies. More recent research theorises that green tea may regulate the production of ghrelin, a hunger hormone, and may also lead to an increase in adiponectin; a hormone involved in the regulation of blood glucose and fat breakdown (15). This same research found that green tea led to a statistically significant reduction of body mass index, without adverse side-effects in woman with central adiposity. Other research has not found the same benefits (16).


The Verdict:

Several of these supplement offer promising potential benefits. Caffeine is the only one that I believe could limit weight loss progress. Ketones require further research before I will feel comfortable recommending them in my clinic. Green tea and carnitine, whilst the evidence is mixed, are safe supplements to use, but I wouldn’t expect anything ground-breaking without putting in the effort of healthy eating and exercise. Omega-3 again has mixed research when it comes to weight management, but it’s very well accepted that omega-3 supplementation has a multitude of health benefits and I believe it’s an must for everyone.

It’s worth noting that the supplements available to the public are often much lower dose than the ones used in research studies and therefore you may not see the same results. Nevertheless, do not exceed the stated dosage without professional guidance.

As a registered nutritional therapist, I believe that a whole body approach is required to achieve sustained weight loss and long-term health. I specialise in creating personalised programmes, based on your unique health profile and nutritional needs. Check out my weight loss programmes here.

Why not join my free Facebook weight loss group for top tips, challenges, support and motivation.




(1) https://www.nature.com/articles/ejcn2013116.pdf

(2) https://nutritionandmetabolism.biomedcentral.com/track/pdf/10.1186/s12986-016-0069-y?site=nutritionandmetabolism.biomedcentral.com

(3) https://www.nature.com/articles/ejcn2015183

(4) http://www.sciencedirect.com/science/article/pii/S0091305706000645

(5) https://journals.lww.com/psychosomaticmedicine/Abstract/2000/09000/Stress_and_Body_Shape__Stress_Induced_Cortisol.5.aspx

(6) https://www.ncbi.nlm.nih.gov/pubmed/26164228

(7) https://www.ncbi.nlm.nih.gov/pubmed/21224234

(8) https://www.ncbi.nlm.nih.gov/pubmed/14693982


(10) http://www.nutrasource.ca/files/rev%20-%202004%20-%20j%20hum%20nutr%20diet%20-%20n3fa%20health%20benefits.pdf

(11) http://www.mdpi.com/2072-6643/8/3/128/html

(12) http://ajcn.nutrition.org/content/early/2010/12/15/ajcn.110.002741.short

(13) http://cancerres.aacrjournals.org/content/77/13_Supplement/4230.short

(14) http://pubs.rsc.org/-/content/articlehtml/2015/fo/c4fo00970c

(15) http://www.sciencedirect.com/science/article/pii/S026156141500134X

(16) http://jn.nutrition.org/content/early/2015/03/04/jn.114.207829.short