Sara Pellegrino is a Dietetics Intern at Tulane University’s School of Public Health. See some of Sara’s great pics and recipe creations on her Instagram (dietitian_girl).
Coconuts have quickly become this season’s most buzzed about nutrition trend. From water, to chips, and now to oil, coconuts are making their presence known throughout the nation’s health food stores. In the case of nutrition and coconut oil, popularity may be overruled by confusion.
Several claims have been made linking coconut oil to lowering cholesterol, increasing metabolism, and decreasing abdominal obesity. All of which may be confusing considering that coconut oil is mainly a saturated fat.
How exactly can consuming fat help you to lose weight?
The first thing to understand is that not all saturated fats are created equal – different types of saturated fats behave differently. Coconut oil is a plant based saturated fat, compared to animal based saturated fats found in meat and dairy.
Coconut oil is comprised mostly of medium-chain triglycerides (MCTs) meaning that each fat molecule is between six and twelve carbons in length, compared to long-chain triglycerides (LCTs), which have between thirteen and twenty-one carbons in length.
The chemical structure of MCTs makes them more easily and rapidly digested than other fats. MCTs are absorbed from the intestine intact and taken directly into the portal system, allowing for quick absorption and utilization. Compared to the absorption of LCTs, in which the fatty acid chain must be broken down and separated from the glycerol backbone before being transported into the blood.
In English: Fats made mostly of MCTs (like coconut oil) are used as a source of energy much quicker than those made of LCTs.
In addition to its rapidly absorbable quality, coconut oil has many other components that contribute to its likeability among consumers. It is rich in lauric acid, which contains antibacterial, antimicrobial, and antiviral properties that have been claimed to help clear up acne, speed up metabolism, and boost the immune system. Lauric Acid also has been shown to improve high-density lipoprotein, HDL, (good cholesterol) levels in the body. Coconut oil has also been shown to increase thyroid function, and may even be a natural treatment for Alzheimer’s disease by creating an alternative source of brain fuel.
With all this in mind, we can now look into the 3 popular studies exploring the effects of coconut oil. Keep in mind, these are all preliminary studies and more clinical studies need to be conducted to find absolute answers.
Study 1: Effects of coconut oil on the biochemical and anthropometric profiles of women presenting abdominal obesity
Subjects: 40 obese women between the ages of 20-40
What the study tested: The cholesterol levels and body measurements of the women after being supplemented with 30mL (2 tbsp) a day of either soybean oil (group S) or coconut oil (group C)
How long did the study run: 12 weeks
What other factors played a role: All the women were is instructed to follow a balanced, low calorie diet and to walk for 50 minutes each day
What were the results?
Coconut Oil- Group C:
Increased HDL (good cholesterol)
Decreased LDL: HDL ratio
Reduced waist circumference/ abdominal obesity
Soybean Oil- Group S:
Increased total cholesterol
Increased LDL (bad cholesterol)
Increased LDL: HDL ratio
Decreased HDL (good cholesterol)
No reduction in waist circumference/abdominal obesity
Pros of the study: The study was double blind, so neither the participants or the researchers knew which supplement they were taking.
Cons of the study: The study did not include a lot of participants. All of the participants were obese; the study did not look at the effects of coconut and soybean oil on a person within a healthy weight range.
The author concluded: “”It appears that dietetic supplementation with coconut oil does not cause dyslipidemia [an abnormal amount of cholesterol and/or fat in your blood] and seems to promote a reduction in abdominal obesity.”
Study 2: Medium-chain triglycerides increase energy expenditure and decrease adiposity in overweight men
Subjects: 24 healthy, overweight men with BMI from 25-31
What the study tested: The body composition and energy expenditure of the men after they were fed diets rich in either MCT (medium-chain triglycerides) or LCT (long-chain triglycerides)
MCT group: 75% of total fat given in the form of functional oil (composed of medium-chain triglyceride oil, coconut oil, flax oil, and canola oil)
LCT group: 75% of total fat given in the form of olive oil
How long did the study run: 28 days
What other factors played a role: The study was a randomized crossover controlled study, meaning all subjects had 28 days of observation with either the MCT or LCT diet, 28 days off, and then 28 days of MCT or LCT diet again.
What were the results? The men who consumed diets rich in MCT saw greater adipose triglyceride (AT) loss, increased energy expenditure, and increased fat oxidation compared to those who consumed the LCT diet
Pros of the study: Every meal was either consumed in the lab, or prepared and eaten at home, so there was a lot of control over the food being eaten.
Cons of the study: The study did not include a lot of participants, and did not cover a large time span. All of the participants were obese; the study did not look at the effects of MCTs or LCTs on people with a healthy BMI.
Discussion: Consumption of a diet rich in MCTs results in greater loss of adipose triglycerides (AT) compared with LCTs, perhaps due to increased energy expenditure and fat oxidation observed with MCT intake. Thus, MCTs may be considered as agents that aid in the prevention of obesity or potentially stimulate weight loss.
Study 3: Medium Chain Oil Reduces Fat Mass and Down Regulates Expression of Adipogenic Genes in Rats
Subjects: Sprague-Dawley rats fed a control high fat diet rich in MCTs and LCTs
What the study tested: The effects of MCTs on body fat mass, plasma leptin and lipid levels, acyl chain composition of adipose triglycerides and phospholipids, adipose tissue lipoprotein lipase activity, and the expression of key adipogenic genes in rats
How long did the study run: 44 days
What were the results?
Rats fed a diet high in MCTs:
– Had smaller fat pads
– A number of key adipogenic genes were down-regulated
– Reduced adipose tissue lipoprotein lipase activity
– Improved insulin sensitivity and glucose tolerance
Pros of the study: The study was very controlled from the housing and temperature the rats were kept in, to the exact dietary composition they were fed.
Cons of the study: Only 16 rats were tested. 8 in the MCT group and 8 in the LCT group
Discussion: These results suggest that direct inhibitory effects of medium-chained fatty acids on adiposity may play an important role in the regulation of body fat development.