Coconut oil has become popular in the past few years with claims about it’s many health benefits including increased energy expenditure, weight loss and a reduction in your risk of heart disease. I have had several friends and colleagues ask me about it, including a friend who went to a fitness boot camp and was told by the trainer to use lots of it to help her lose weight! This sounded a bit suspicious to me so I thought I would investigate these claims to see if it is a product we all should be using or not.

What is coconut oil?

Unlike its name, coconut oil is solid at room temperature. This is because it contains 75-95g of saturated fatty acids per 100g of product.

coconut oil nutritional info
Fatty acids fall into 3 groups – saturated, monounsaturated and polyunsaturated. They are also found in different lengths in the diet. Long chain fatty acids chain length are between C12-C20 (C stands for number of carbons in the chain length) and medium chain fatty acids are C6-C10. The fatty acids in coconut oil are lauric (C12), myristic (C14), capryllic (C8), capric (C10) and palmitic (C16) fatty acids, a mixture of long (LCT) and medium chain fats (MCT).
cocnut oil fatty acids

It can be used for cooking and is also commonly used in cosmetics and soaps as a fragrance or moisturizer. It is expensive to buy compared to vegetable oil. Coconut oil cost between £1.80-£2.70 per 100mls, olive oil £0.35-£0.70 per 100mls and rapeseed oil only about £0.30 per 100mls.

Can it help you lose weight?

There is little evidence in humans to be able to say that coconut oil can help you lose weight. The studies that are published are small in size. One study with 40 obese women aged 20-40 years were split in to 2 groups. One group received daily dietary supplements comprising of 30mls of soy bean oil and the other coconut oil over a 12-week period. During this time they were instructed to eat a balanced low calorie diet and to walk for 50 min per day.  In the coconut oil group there was a modest decrease in waist circumference compared to the group on soy bean oil, but no difference in BMI or fat mass between the 2 groups (1).
Another study in 2011 looked at 20 Malay men and women (very small number for a study!) to investigated the impact of 30mls of coconut oil on body weight. There was a significant reduction in waist circumference in men, but not women. No other measures of body weight showed any difference (2). So according to these 2 small studies, having 30mls of coconut oil (instead of vegetable oil) every day while eating a low calorie diet could have a greater impact on decreasing your waist circumference, but you are not likely to lose any more total fat mass or decrease your BMI using coconut oil over vegetable oil.

Can coconut oil increase your energy expenditure and help you lose more fat?

Many internet sites about coconut oil claim that it can increase your energy expenditure. There are only a few studies looking at this that they quote. All the studies are very small (less than 10 subjects) and they use MCT oil not coconut oil (3,4,5). We can’t apply the results of studies with MCT oil to coconut oil. MCT oil is mainly made up of C8-10 fatty acids (derived from coconut oil and and palm kernel oils) and is liquid at room temperature, where as coconut oil is solid and mainly made up of C12 fatty acids. There is not enough evidence to support this claim.

Can coconut oil improve your blood cholesterol?

Coconut oil is very high in saturated fat and diets high in saturated fats are associated with increased bad cholesterol in the blood. There has been speculation that some of the saturated fats in coconut oil may be better for us than others, but there is not enough good quality evidence to give us the answers (6). In a recent (2014) review of the literature by the New Zealand Heart Foundation (7) – they conclude that there is a lack of evidence to say that coconut oil is super-healthful and it is not suggested that coconut oil is any better than other saturated fats. When compared to other fats, it is not as bad as butter in increasing total cholesterol but does increase total cholesterol more that vegetable oils. They suggest people following a western style diet should not swap from unsaturated oils to coconut oil. So currently we do not have enough good evidence to say it can improve your cholesterol.

What about indigenous people that eat a lot of coconut?

People who consume traditional diets high in coconut flesh and milk (which contain fibre), together with polyunsaturated fats (particularly from fish) and vegetables (fibre) in the absence of excessive carbohydrates may not pose a risk for heart disease in their traditional diets (6).

So should we eat coconut oil?

If you like the taste of coconut oil in your cooking and on your food, then using a small amount now and again will not be harmful. Currently their is not enough evidence to support it’s suggested health benefits associated with eating lots every day. Stick to the current recommendations of using unsaturated oil (olive, vegetable, rapeseed, sunflower) as your usual every day oil. This will also save you money as coconut oil is much more expensive than vegetable oils!

In conclusion

If something sounds too good to be true (i.e. eat lots of coconut oil and you will lose weight!) then it probably isn’t true. Unfortunately there are people out their giving nutritional advice that haven’t even looked at the facts or the evidence…. they have probably just read a health blog from someone as equally unqualified to give nutritional advice…! Trust a Dietitian.

References

1.  Assunção ML1, Ferreira HS, dos Santos AF, Cabral CR Jr, Florêncio TM. Effects of dietary coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity (2009). Lipids 44(7):593-601.
 2. Liau K M, Lee Y Y, Chen C K, Rasoo A H G. An Open-Label Pilot Study to Assess the Efficacy and Safety of Virgin Coconut Oil in Reducing Visceral Adiposity (2011). ISRN Pharmacol. 949686.
3. Seaton TB, Welle SL, Warenko MK, Campbell RG. Thermic effect of medium-chain and long-chain triglycerides in man (1986). Am J Clin Nutr. 44(5):630-4.
4. Scalfi L1, Coltorti A, Contaldo F. Postprandial thermogenesis in lean and obese subjects after meals supplemented with medium-chain and long-chain triglycerides (1991). Am J Clin Nutr. 53(5):1130-3.
5. Dulloo AG1, Fathi M, Mensi N, Girardier L. Twenty-four-hour energy expenditure and urinary catecholamines of humans consuming low-to-moderate amounts of medium-chain triglycerides: a dose-response study in a human respiratory chamber (1996). Eur J Clin Nutr. 50(3):152-8.
6. British Heart foundation. https://www.bhf.org.uk/heart-matters-magazine/nutrition/ask-the-expert/coconut-oil
7. Fnzifst LE. Coconut oil and the Heart, Evidence Paper (2014) New Zealand Heart Foundation.