Thursday, 3 July 2014

Blood glucose

So I gave up processed sugar on 16 June 2014. Going to find a book on the subject having decided it was a healthy option is in my memory tag for the day.

I've been reading up since then and following a low GI diet: eating natural foods, predominantly those with a low glycaemic index.

I have lost a bit of weight (now down to 80 kg – BMI below 25) and reduced my body fat (23.8% – classified as 'good').

I feel better in a way that is difficult to explain.

A bit more comfortable in my body, never feeling stuffed. And with clearer eyesight, it seems. Which is reassuring given in my hypochondria attack back in March when beset by tiggling fingers, I ran on a beach with my eyes closed, thinking how it would be if I lost my sight. That worry has receded, though I do still have the tingling fingers, and cracking spine.

I am eating well and enjoying food. I do sometimes feel a little hungry and so snack between meals, as advised, but on healthy things like carrots, oranges and apples. Or crackers with peanut butter.

The GI diet is supposed to maintain blood sugar at a more balanced level through the consumption of carbohydrates that take longer to break down.

I thought I would find out what was happening to my blood sugar and so bought a test meter and finger pricker on 27 June (yes, it's in my memory tag).

I've done various tests since then and found my blood sugar is very stable. To see how it might have varied in the past, I turned the clock back and with my evening meal yesterday of low-fat french fries, fish in butter sauce and vegetables (I did eat pretty healthly in any case) had a can of coke, followed by an icecream. Oh, and a chocolate bar while I was cooking.

According to the nutrition app on my smartphone, I have topped 100g of sugar today. Over three-quarters will have been processed sugar, rather than natural sugars in fruit and vegetables.

The World Health Organisation recently dropped its recommendation on sugar intake to 5% of calories, or about 25g for a adult male. Reports on this and other sugar warnings started me thinking about giving up sugar in the first place.

Note, that the can of coke had 35g of sugar in it alone. The chocolate bar and ice cream each had 22g. So that's 79g of processed sugar, over three times the recommendation, in just three processed foods.

The results of my experiment do suggest I have a lower blood glucose spike following the GI diet.

I've only run this experiment once and there is a margin of error in readings, but here are the figures.

A fasting blood test (after 8 hours with no food) using my new meter gave me a blood glucose reading of 4.7 mmol/l. (I have a clinic fasting blood test result from 2012, which records a value of 4.3 mmol/l, so a similar order).

My high-sugar meal and drink gave me a peak of 7.9 mmol/l. I measured from about 20 minutes after eating (6.3 mmol/l) then at 20 to 30 minute intervals. The high reading was at nearly 50 minutes. At 75 minutes, I was down to 6.0 mmol/l.

After 2 hours I was down to 5.4 mmol/l and at 3 hours at 5.3 mmol/l. This seems to be my steady-state level between eating.

I measured my blood glucose the day before the high-sugar test as a control. I ate a similar meal without the processed high-sugar food and drink. An hour after eating, my blood glucose was 4.9 mmol/l. Two hours after eating it was 5.5 mmol/l. Which suggests it takes longer for the glucose to arrive and when it does, it is less dramatic.

Having made various measurements on other days before and after eating, it seems my blood glucose on the GI diet fluctuates between 4.8 to 5.8 mmol/l. One day I went for a 20-minute run an hour after eating and it dropped to 4.6 mmol/l, but an hour later recovered to 5.3 mmol/l without eating anything else. In fact, this was on a low-calorie day in the fasting diet I follow (two low-calorie days per week – see 'fast living' blog posts).

The peak of 7.9 mmol/l appears to show the impact of the high-sugar intake. It is within acceptable limits according to the literature I've read. My body produced insulin to instruct my cells to absorb glucose and the level dropped to the steady-state level in 2 hours.

But the swing is less marked with the GI diet. Apparently this translates into less risk of developing type-2 diabetes, which arises when cells become less responsive to the insulin signal and blood sugar can run out of control.

This has only been a snapshot test, but it does seem to support the theory.

The GI diet is no problem to follow, though it is making me averse to processed foods. There are whole aisles in the supermarket that I now ignore as they scream 'sugar' at me.

In fact, I am enjoying food more, even embarking on some of the recipes in the books I've been reading.

Goodness. I even baked my own wholemeal bread last week.

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