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Friday, 22 March 2013

Enemy, thy name is... definitely not fat

Do you like being lied to?

Generally we are conditioned to implicitly trust information coming from a position of authority. It comes from childhood where we are told to trust adults, our teachers, our god; we must have faith. For many unimportant things it makes sense. Why would you waste your time questioning something which has little impact on your life? 

On the other hand, with things you are passionate about, things which you value, things that are important in life -   no matter how well read someone is or how strong their reputation is - they need to be able to back up what they say with some facts. Never is this more important than with your health.

Saturated fat has long been the hot topic of conversation when discussing causes of cardiovascular disease (CVD). The hypothesis is that too much clogs up our arteries, raises blood pressure and ultimately leads to our demise. The main sources are dairy, processed meats, dessert food, pastries and chocolate. We are told that saturated fat must be reduced in order to lessen the risk of disease.

So rather than having faith in the hype, I'll present the evidence and then leave it up to you to decide. 




When dietary saturated fat is reduced, the calories have to come from another energy source. From my experience , sandwiches, rice cakes, low cal biscuits and low fat yoghurts - all of which are low protein, low fat, high carbohydrate options - tend to be chosen for their healthy virtues. But what does research predict the effects will be on your cardiovascular system?

Siri-Tarino et al. 2010 - "There is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD"

Researchers conducted a meta-analysis of over 350,000 people, comparing different dietary interventions with risk of contracting CVD. 

After conducting a meta-analysis, researchers found that reduction of dietary saturated fat only affected CVD risk factors when altering the ratio of fat intake.  A ratio of roughly 2:1 unsaturated to saturated was found to be optimal, when fats made up around 40% of the calorific intake. 
Even more interestingly, when the calories from saturated fats were replaced with carbohydrates, particularly refined carbohydrates, the risk factors linked with CVD became more severe. 

Could this be the reason that CVD is the biggest killer in the UK? Refined carbohydrates cause saturated fats to become dangerous to heart health. The worrying thought is that most common sources of saturated fat come with a carbohydrate coating, think; cakes, biscuits, chocolate, pies, pasties, sausage rolls, it's all there.
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The implications of this extend beyond CVD to body composition. If refined carbohydrates are the cause of more bad fats circulating our bodies, then carbohydrates make us more likely to store fat and have an undesirable physique - and that's it.

Not quite, the conclusions that the above foods aren't good for you isn't new. The context of why they are unhealthy might be for some, but practically nothing has changed. So why do people continue to eat these foods? The simple answer is addiction. 



Te-Morenga et al. 2012 - "Among free living people involving ad libitum diets, intake of free sugars or sugar sweetened beverages is a determinant of body weight."

A study published this year in the British Medical Journal found that refined carbohydrate consumption was a predictor of body weight in the general population. The reasoning proposed was that processed foods trick your body into consuming more energy in the form of sugar than you would otherwise. 

Think of this as an example; if you were asked to consume 2 glasses of apple juice with breakfast, most wouldn't think twice. If you were asked to consume 8 apples, and then eat breakfast, you wouldn't even get close. Processing takes all the fibre out and leaves only sugar and water. The same principle applies to bread, pastries, and chocolate. 

Avena et al. 2008 - "The theory is formulated that intermittent, excessive intake of sugar can have dopaminergic, cholinergic and opioid effects that are similar to psychostimulants and opiates, albeit smaller in magnitude." 

These foods alter the brain chemistry, they are addictive and people can become legitimately hooked on them. When you get a big sugar hit, from something like a soda or a bar of chocolate, your brain chemistry changes and you feel good. If you do this regularly, your brain will become dependent on sugar, then the addiction begins. 

This is the point where people begin to become dependent on sugar, so much so that when an alternative sugar free diet is proposed they ask the question 'Well what is there left to eat?'.
The answer is to control blood sugar by eliminating refined carbohydrates and replacing them with fibrous types, then replacing calories with protein and a good balance of fats.  

If you genuinely are addicted to carbohydrates, then chances are this is going to be a very long and drawn out process, but stick with it, your heart will thank you when you are older. 

References
Siri-Tarino, P. (2010). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. American Journal of Clinical Nutrition. 91 (3), p535-546.

Te Morenga, L., Mallard, S., Mann, J.. (2013). Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies. British Medical Journal. 346 (1), e7492.


Avena, M., Rada, P., Hoebel, B.. (2007). Evidence for sugar addiction: Behavioral and neurochemical effects of intermittent, excessive sugar intake. Neuroscience & Biobehavioral Reviews. 31 (1), p20-39.


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