28 Aug Importance of Insulin
Here’s the 5th in Andy’s series….this is a great one. It explains a huge problem in really nice terms….read it and action it now!
“Insulin was one of the first hormones to evolve in living things. Virtually all animals secrete insulin as a means of storing excess nutrients. It makes perfect sense that in a world where food was often scarce…” Mark Sisson, Primal Blueprint
Except food is no longer scarce. Humans used to ‘feast and fast’, that’s what we are adapted for, now most of us just feast, we’ve forgotten how to fast.
If there is one hormone that it’s worth spending a few minutes to understand the basics of it’s insulin, sometimes referred to as the ‘master hormone’. Like so many things in life, a moderate amount of insulin can be good, a lot can be bad. Insulin levels can be regulated by what you eat and how you exercise.
Insulin delivers nutrients to muscle, liver and fat cells. It’s an elegant system whereby cell receptors use insulin as a key to unlock cells and with the door open the cells can gather the nutrients they need from the bloodstream. Importantly insulin also removes excess blood sugar, which is toxic above a certain level, from the bloodstream.
Anthropologists estimate that our hunter gatherer ancestors consumed around only 80g of carbs a day – mainly from fibrous roots and tubers. So what you say? Well that’s what our bodies are optimized for even today. Evolution takes a long time to drive change (estimated at 40-70,000 years for random genetic mutations to take effect in a population) even if indeed we are still evolving as opposed to just genetically drifting (let’s save that one for a future blog…).
(Interlude: At this point whilst I was building up a head of steam writing about evolution the doorbell rang and a kindly Jehovah’s Witness, Brian, appeared on my doorstep. We spent well over 30mins engaged in a lively debate about creationism and evolution. Perfect timing, the irony wasn’t lost on me. As with any such debate, for me it’s about evidence, show me the evidence…)
Back to the evidence…Insulin evolved in this low carb / low sugar context to sweep excess sugar in the form of glucose from the bloodstream. What happens to this excess glucose? As with a lot of things in life, it depends on the context of what you’re doing when you eat:-
If you’re exercising – excess glucose (or at least some of it) will be burned immediately as fuel. Insulin allows glucose to burned first as a fuel source if there is an immediate requirement, slowing the burning of fat.
Post exercise – insulin directs excess glucose to be stored as glycogen in the liver and muscle cells, topping up glycogen stores to be used as an energy source for future activity.
If you’ve been sat on the couch all day – when glycogen stores are full then insulin will help any remaining glucose to be converted to triglycerides and transported to fat cells for storage.
That’s the key part – when glycogen stores are full insulin becomes a fat storage hormone.
This is a beautiful example of evolution – the body making the most of scarce resources. Those who feasted on wild berries and fruit at the end of summer and could successfully convert this sugar to fat (via insulin) had a higher chance of survival through harsh winters.
Fast forward to where we are now, surrounded by sugar at every eating opportunity but insulin continues to do the same job it did 10,000 or more years ago, sweeping sugar from the bloodstream and dumping it as fat. Great if you’re fattening up for a harsh winter (does anyone do that anymore?), not so great if you’re eating 3 or more high sugar meals a day and the exercise highpoint is climbing the stairs to bed.
To put all this into context, it is estimated that the blood volume of most mammals is approximately 7 to 9% of ideal bodyweight. In humans this equates to around 6 – 8 pints of blood. The optimum amount of glucose dissolved into the bloodstream in a healthy (non diabetic) person is about a teaspoon, 5 grams, anything more starts to become toxic, fall below this and you’ll start to pass out. A regular can of coke contains 35g of sugar, around 7 teaspoons.
Insulin was not ‘designed’ for this massive sugar load, hence people develop insulin insensitivity whereby our receptor cells become increasingly insulin resistant, causing more insulin to be pumped out in a vicious circle ending for many in Type II Diabetes, a lifestyle epidemic of our modern times.
So what can we do? Evidence clearly shows that controlling / minimizing insulin production by cutting down on sugar intake and taking regular exercise will stack the cards in your favour, you’ll be less likely to develop insulin insensitivity, less likely to become stage II diabetic and less likely to put on weight as you get older.
Sounds good to me…next week as we approach Christmas – ‘Calories in, calories out – it’s more than just a maths problem !!’
Resource of the week:- http://www.marksdailyapple.com/diabetes/