As to heart rate going up after meals, I also wonder about that. Is it because the blood sugar is higher after meals that heart rate is up? Or is it because digestion is an energy-intensive process that it demands more energy, and so metabolism and heart rate naturally has to increase?
@CLASH I think the heart rate after meals shouldn't be relied upon as an indication of our metabolic rate. It goes up because there's a deluge of glucose going into the blood, and the body is absorbing it at a high rate, which it can. I tested my blood sugar right after a meal, and my blood sugar was at 140. I was initially shocked at seeing that huge a number, but then realized it must be normal given how fast rice is digested and assimilated into blood. With that much sugar being metabolized, it's likely metabolism would increase, and we would see that in increased heart rates.
On the other hand, I am curious to find out if people with poor tissue sugar absorption - the insulin resistant people - would experience an increase in heart rate. Maybe they would, but the increase in heart rate may be smaller. And it would be interesting to see the effect on heart rate compared between taking sucrose and taking glucose for insulin-resistant people. I would expect increase in heart rate to be more pronounced when they take sucrose.