Insulin resistance is a hallmark of obesity and diabetes, and occurs when cells need larger amounts of insulin than normal to take up glucose. It is also a hallmark of the couch-potato lifestyle, because lack of exercise and eating lots of refined carbohydrates, both of which characterize the couch potato, lead to insulin resistance.
Since it is so characteristic of obesity, diabetes, and being a couch potato, as well as old age, one might think that insulin resistance increases the risk of disease and is in general a bad thing, and one would be right.
Gerald Reaven, the doctor who discovered what is known as the metabolic syndrome, that is, the pre-diabetic state, along with colleagues, wanted to find out just how important insulin resistance is for health. (One of the co-authors here is Francesco Facchini, whom as we recently saw did a lot of work on the relation between iron levels and insulin resistance, and wrote a blurb for my book on iron.)
To do this, they took 208 “apparently healthy”, non-obese volunteers (98 men, 110 women), and determined their level of insulin resistance through the measurement of steady state plasma glucose (SSPG). The explanation of the SSPG is rather technical, but we’ll just note that it is not the same thing as a fasting plasma glucose. (The Journal of Clinical Endocrinology & Metabolism.)
The subjects were divided into tertiles (thirds) of insulin resistance, low, medium, and high.
They then followed the subjects for an average of 6.3 years each and looked for the “clinical endpoints” of hypertension, coronary heart disease, stroke, type 2 diabetes, or cancer. They found a total of 40 clinical endpoints in 37 of the subjects.
The shocking conclusion: ALL of them were in patients with some degree of insulin resistance. Graph below.
Twenty-eight out of the total 40 clinical events were seen in 25 individuals (36%) in the most insulin-resistant tertile, with the other 12 occurring in the group with an intermediate degree of insulin resistance. Furthermore, insulin resistance was an independent predictor of all clinical events… The fact that an age-related clinical event developed in approximately 1 out of 3 healthy individuals in the upper tertile of insulin resistance at baseline, followed for an average of 6 yr, whereas no clinical events were observed in the most insulin-sensitive tertile, should serve as a strong stimulus to further efforts to define the role of insulin resistance in the genesis of age-related diseases. [My emphasis.]
Just to repeat, no one in the lowest tertile of insulin resistance developed any of the major diseases of aging and/or civilization in 6.3 years of follow-up. Insulin resistance is an independent predictor of developing one of these often fatal illnesses.
We know that a low-carbohydrate diet is an anti-aging diet, and one of the ways that it slows aging is very likely by preventing the development of insulin resistance.
Exercise capacity is the strongest predictor in men of the ability to live to the age of 90. Here again, exercise strongly prevents insulin resistance, so this is probably one of the major ways that exercise helps men (and women too) live longer.
So, what to do to prevent landing in the upper two thirds of insulin resistance and dramatically increasing your odds of getting hypertension, heart disease, cancer, and stroke?
1. Watch the carbs. If you ingest sugar in any form, whether in pastries, candy, or soda, stop. Refined carbohydrates, such as in pasta, bread, tortillas, cereal, and so on, turn into glucose after eating, so they too are implicated, and should be avoided.
2. Exercise. Lift weights a few times a week, and do some less strenuous exercise such as walking on the other days.
3. Don’t be a couch potato. Even when you’re not actively exercising, avoid being sedentary. Stand don’t sit; consider a standing desk if you work at a computer.