by Dr. Haran Sivapalan

“It’s not the pastries that hurt, it’s the climbs.”

So said Eddy “The Cannibal” Merckx, arguably the greatest rider of all the time, who, before a big race, also feasted not on human flesh, but on cheese, ham and steak.

Ironically, a diet full of pastries, cheese and red meat might actually hurt climbing performance. This is because such foods are rich in saturated fat – a type of fat linked to heart disease, elevated blood levels of ‘bad’ LDL cholesterol and, of detriment to climbing ability, weight gain. 

Interestingly, however, not all of us are at the same risk of weight gain when eating a diet that is high in saturated fat. Research suggests that certain variants of our APOA2 gene make some of us 1.8 times more likely to become obese if we follow a high saturated fat diet.   

What is saturated fat?

Saturated fats are found in foods such as fatty meat, full-fat dairy products, palm oil and coconut oil. 

On a molecular basis, saturated fats are distinguished from unsaturated fats (including mono- and polyunsaturated fats), in that their fatty acid chains contain no double bonds. They also tend to be solid at room temperature. 

While a small amount of saturated in our diet is fine, excessive intakes are linked to weight gain, poor insulin sensitivity and increased levels of LDL cholesterol. LDL cholesterol is often referred to as ‘bad’ cholesterol, as it transports cholesterol (a fat-like substance) away from the bloodstream to be deposited in arterial walls. In this respect, saturated fat is also thought to increase the risk of heart disease, although this is now a topic of much debate

Compared to unsaturated fats, saturated fats are also more likely to cause accumulation of visceral fat – the type of body fat that surrounds our internal organs and can lead to inflammation and poor insulin function. 

Given these health risks, the World Health Organisation currently advises limiting your saturated fat intake to 10% of your daily calories. There are 9 calories in a gram of saturated fat, so if you’re eating 2,500 kcals per day, this equates to about 28 grams of saturated fat each day. 

When it comes to weight gain however, studies show that some of us are more likely to pile on the pounds and become obese when consuming over 22g saturated fat per day. It all depends on our genetics, with one of the key genes being APOA2. 

What is the APOA2 gene and how does it affect my risk of weight gain?

Your APOA2 gene codes for a protein called Apolipoprotein A2. This belongs to a class of specialized proteins called apolipoproteins. If that word sounds familiar, it’s because we’ve encountered these molecules before in the APOA5 and triglycerides blog

To recap briefly, apolipoproteins guide the movement and the metabolism of particles (called lipoprotein particles) that transport fat and cholesterol in the bloodstream. Given this role, changes in the level and activity of apolipoproteins can influence how we use and store fat. 

On this note, variants of our APOA2 gene that affect the production and activity of apolipoprotein A2 may go on to alter our risk of weight gain. For example, one variant of the APOA2 gene, called the ‘C’ allele, is linked to reduced production of the apolipoprotein protein. Studies show that inheriting two copies of this gene variant (known as having the ‘CC’ genotype) is associated with a 6.4% greater increase in BMI and 1.81 higher chance of becoming obese. 

Importantly, these enhanced risks only occur when following a diet that is high in saturated fat (defined in the study as over 22 g per day). When people with the CC genotype consumed a low saturated fat diet (less than 22g per day), the risk of obesity was normal. 

So, if you do happen to have the CC genotype, it’s advisable to replace saturated fats with healthier mono- and polyunsaturated fats such as those found in oily fish, nuts and olive oil. Of course diet is only one part of the picture, you can also minimise your risk of weight gain with regular exercise. 

Coaching perspective  

The variance in the APOA2 gene will definitely affect advice on nutrition and choices of food, particularly around post ride/recovery meal choice when the drive to eat may outweigh the desire to eat sensibly. This also becomes important with extra/ultra endurance events where meals would be taken during the event. The knowledge of the specific CC genotype will help guide discussion with the athlete on food choices within any structured training regimen. 

This blog comes courtesy of Dr. Haran Sivapalan, Science Writer at FitnessGenes, with input from Caroline Stewart, Spokes coach, for the ‘Coaching Perspective’.

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