Fat: Not So Bad After All?

Monday, 12 June 2017, 12:21 PM
By James Jubb

It’s becoming common knowledge that not all fats are bad for you. In fact, people often talk about “good fats” and “bad fats,” but this doesn’t truly grasp the science as to how the fats really affect us. Instead it raises a few questions like 'which are “good” fats and how bad are the bad fats?’, ‘what makes them bad?’ and ‘are they as bad as everybody says?’

As you will see on the nutritional information of most food products, fats can be categorised into saturated and unsaturated fats. Saturated fats are fats where all of the carbon bonds are “saturated” with hydrogen molecules so there are no double bonds (remember learning this in chemistry?). Unsaturated fats have at least one double carbon bond so not all the carbon molecules are saturated with hydrogen. Then there are mono unsaturated fats which have one double bond (mono=one) or poly unsaturated fats which have more than one double bond (poly=many).

Generally, people call saturated fats “bad fats” and unsaturated fats “good fats” based upon their effects on cholesterol. 

Cholesterol are lipoproteins. These are fats bound together by protein to allow them to mix with and move through water inside and outside of cells. Cholesterol can also be broken down into a few categories, low density lipoproteins (LDL) and high density lipoproteins (HDL). 

LDL are often considered bad and are said to clog your arteries, but this is not true. Oxidised LDL is the true culprit, as LDL oxidises it contributes to arterial-clogging plaque which causes cardiovascular heart disease. 

HDL, high density lipoproteins, are the good guys. Not only do they travel freely through the blood stream, but they attach to and prevent the LDL from oxidising to defend against cardiovascular heart disease. 

It has been found that there is an association of high LDL levels and cardiovascular heart disease but that doesn’t mean that LDL is the cause. In fact there is no evidence that cholesterol causes heart disease and the US Dietary Advisory Guidelines Committee even amended their advice to say that cholesterol is no longer a nutrient concern. The idea that cholesterol caused cardiovascular heart disease was a theory with insufficient evidence and has been proven wrong. It can be shown with coronary calcium scans that someone with a high LDL can have pristine arteries. As far as we know it, LDL is not bad and the scans also show that you want to maximise HDL to stop the LDL from oxidising because it is oxidised LDL that is bad. 

Unsaturated fats have been shown to raise HDL levels which help to reduce risk of cardiovascular disease, hence the term “good fats”. They also raise LDL in some cases but the HDL prevents significant oxidization. 

Saturated fats are regarded as “bad fats” but this is a misinter- pretation for two reasons. 

Firstly, they have been found to raise LDL and lower the HDL:LDL ratio (a ratio often used to discuss cardiovascular heart disease risk which, ideally, should be raised). However, as we just found out, LDL means nothing. Coronary calcium scans also show that the LDL produced by saturated fats are not significantly contributing to plaque on arterial walls meaning that it is not resulting in significant LDL oxidisation. 

Secondly, saturated fats are labelled as being bad when compared to unsaturated fats. This means that they are bad in relative terms, it’s like saying that a power nap is bad relative to sleep when we know that power naps aren’t bad. The comparison creates a lot of misinterpretation. Saturated fats should be called something like “not as good fat” to clear the water for everyone. It is only bad if the LDL it produces starts oxidising which can be prevented by HDL. 

In fact, a 2010 meta-analysis (overall summation of all of the studies) concluded that there was no significant evidence that dietary saturated fat is associated with or causing an increase in risk of cardiovascular heart disease. Additionally, in a study of the effects of substituting complex carbohydrates for saturated fats it was found that the consuming saturated fats instead of complex carbohydrates lowers cardiovascular heart disease risk and can improve insulin sensitivity (insulin resistance, the opposite, is a cause of diabetes) with no negative effect on energy expenditure. This infers that if saturated fats are “bad” then complex carbohydrates must be “extremely bad.” So saturated fats are not bad and are better for you than carbohydrates. They are “not as good fat.” 

Are there bad fats after all then? Well, yes, Trans fats should be avoided. 

Trans fats are solid fats produced artificially by heating vegetable oils with metal catalysts and hydrogen. This causes the carbon bonds to form a straight structure (a “trans” chemical shape). Naturally occurring unsaturated fats do not have this feature. Trans fats are bad because they have been consistently shown to increase risk of cardiovascular heart disease by contributing to arterial plaque. 

As a side note, it’s also important to be aware of your omega 6 : omega 3 ratio. Omegas are essential fatty acids as your body can’t create them and needs them but it has been found that if you do not have enough omega 3’s to balance out the omega 6’s, there can be increased risks of many diseases like cancer and cardiovascular heart disease. The omega 6’s are so widely consumed in the western diet that you should try to limit them and maximise your omega 3 consumption to reduce the ratio to about 1:1 (most western ratios have been found to be 15-17:1). 

But what about my gallbladder, surely eating fat can’t be good for it?! It was thought years ago that fat is what causes gallstones and other gallbladder related problems. This has actually been proven to be another false assumption. The gall bladder fills up with bile to release in the digestion process to break down fat. That’s where the confusion was, the more fat you eat, the more the gallbladder swells to release bile and the excess fat forms gallstones. However, what has been found to really happen is that the fats use the bile to digest and if there is little or no fat, not all of the bile is used up and some bile is left long enough to form gallstones. A Swedish survey of 145 people who switched to high fat diets found that 68% of the participants with gallbladder problems said that they disappeared completely, 17% said that their situations improved, 12% unchanged and only 3% worsened. 

So there are good fats and there are bad fats but it’s just that most of the hype is directed at the wrong culprits. Unsaturated fats are “good” and saturated fats are “not as good fats” which are better for you than complex carbohydrates and a diet high in unsaturated and saturated fats may help with gallbladder problems. Trans fats, however, should be avoided. They are the real “bad fats” and we should try to maximise our body’s HDL levels by eating lots of unsaturated fats. All this leads to an interesting question though, should we, as cyclists, be eating more fats – saturated and unsaturated – in place of carbohydrates?


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