insulin and aging 101 (as promised)

this post is dedicated to those who love science as much as i do :) i've presented the information in a simple, easy-to-follow format for the benefit of anyone willing enough to read on.

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insulin-resistance and its contribution to aging

key point: too much insulin in the blood has profound pro-aging effects

let's start with the basics:

• carbohydrates are made up of glucose molecules
• when glucose enters the blood, within minutes your pancreas secrete the hormone insulin
• why? - to get the glucose out of your bloodstream and into your cells ASAP
• how? - your cells have receptors (like trapdoors) for insulin; a cell needs insulin first (via receptor sites) in order to be able to absorb and metabolize glucose
• as you age, your cells lose more and more of these insulin receptors

so what??

let me use this example:

a five-year-old and a fifty-year-old each have a scoop of ice cream

- five-year-old:

• little insulin secreted
• sugar quickly cleared from blood
• insulin levels quickly return to normal

- fifty-year-old:

• a lot more insulin secreted (to make up for the delay in finding the few insulin receptors that are left)
• sugar takes longer to be cleared from blood
• insulin levels take longer to return to normal (ie. more insulin in the blood for a longer period of time)

again... so what??

when your insulin levels are high:

• your body is adding fat onto your waistline
• your blood pressure goes up
• your triglycerides go up (triglycerides are what make up body fat, like how glucose molecules make up carbohydrates)
• you feel tired all the time (because it takes longer to get glucose into your cells; remember that your cells use glucose as fuel, and a slowed-down metabolism of glucose means that your cells aren't getting all the fuel that they need to function top-notch)
• your kidneys retain salt and fluids, which further elevates your blood pressure
• your arterial walls get thicker and harder -> a precursor to heart disease and poor *peripheral circulation (*in other words, blood has a harder time circulating in your skin and you slowly lose your skin's radiance and elasticity, resulting in wrinkles)

are you scared of insulin yet? there's more:

• as long as insulin levels remain elevated, the effects will override your dieting efforts and make it nearly impossible to take off fat
• any intake of carbohydrates will trigger the production of a LOT of insulin to carry out what used to be a small clean-up job (back when your cells had way more insulin receptors)
• a LOT of insulin will of course linger in the blood longer than a LITTLE insulin
• as time goes by, blood sugar goes up and stays up longer because the cells are doing a poorer job of bringing in insulin... and the result? even more insulin is produced!

what does a high blood sugar level lead to?

• GLYCATION - one of the biggest reasons we age
• when glucose levels are elevated in the blood, glucose attaches to proteins or DNA instead of being utilized as fuel for energy
• this irreversibly compromises the function of the protein or DNA (that is, the cell won't work like it originally used to, and this degeneration promotes aging)

last but not least, insulin's extended presence:

• activates cholesterol-making machinery
• did you know that eating red meat has a relatively tiny effect on your cholesterol levels compared to that of a moderately (not even highly, but moderately!) elevated insulin level?? the cholesterol you eat is only responsible for 20-30% of your circulating levels; the rest is manufactured courtesy of insulin!
• the key point is that eating carbohydrates ultimately has more impact on your cholesterol levels than eating high-fat foods

conclusion: insulin-related metabolic changes foster aging and associated major degenerative changes such as obesity, heart disease, and type 2 diabetes. simply put, insulin has a great deal to do with how gracefully or poorly you age.