Just taking a break from the busy stuff going on away from the blog. This paper deserves a brief comment. Here is a mainstream discussion, thanks Elizabeth. [And here is the text for when the blog link goes down].
"Being skinny confers no advantage when it comes to the risk of dying suddenly from cardiac causes"
That lead statement about being skinny is somewhat misleading. A 99% increase in risk is not quite neutral....
So how does a lipophile see this paradox?
Well, the first thing is that the population is pre-selected. They have (a) had a heart attack and (b) have cardiac muscle wastage.
It's a little pointless going through the detail of the studies linking hyperglycaemia to heart disease when Jenny Ruhl has very neatly collated the studies that matter. I have mentioned the role of hyperglycaemia in cardiac muscle apoptosis before. Ischaemia and apoptosis is a great recipe for heart failure.
So we can reasonably describe this population as a set of people who have been routinely achieving post prandial blood glucose levels in excess of 8.0mmol/l, ie about 140mg/dl, almost certainly for years.
How they have achieved this seems unimportant, what matters to me is that by definition this is a group of recurrently hyperglycaemic people. Their LDL cholesterol level is of no interest and, thankfully, does not get mentioned here.
Why do the skinny people do so badly?
These people are skinny. They don't eat huge amounts of calories, but what they do eat spikes their blood sugar. They may well not be hyperinsulinaemic. After all, they are not squirreling away fat and they are allowing their blood sugar to rise... Those suggest, if anything, a blunted insulin response. Is someone with a BMI of 21, who has just had a heart attack, going to set out to lose a serious amount of weight? No, I doubt it. Cutting the fat would probably be the standard advice, obviously cutting saturated fat specifically. But backing off on fat (that scary stuff which Ancel Keys told us causes heart attacks, and cardiologists still believe him!) will invariably lead to increased carbohydrate intake. We know these people already develop post prandial hyperglycaemia. Low fat means more hyperglycaemia. Hyperglycaemia = death.
What about the healthier fatties?
Obviously these people are recurrently hyperglycaemic too, again because they are in the same cardiovascular situation as the skinnies. But they must have been eating a bit more of everything in the past than the thin people. They have to have eaten more to (a) eat enough calories to move themselves around, (b) eat enough calories to provide enough for their basal metabolic rate and (c) eat enough fat to go in to storage in their adipocytes.
However, they do have considerable scope for weight loss and ANY reduction in calorie intake is likely to reduce carbohydrate calories somewhat, as well as fat calories. The two tend to go together. Any decrease in carbohydrate calories will reduce hyperglycaemia in a person who is proven to develop post prandial hyperglycaemia.
Even cutting fat can be good. Less omega 6 PUFA and less trans fats from the diet, both of which, during weight loss, get replaced by an excellent mix of saturated fat with some mono unsaturated fat from butt fat. Butt fat, once again, is an excellent and healthy source of calories.
I have no idea whether surviving a heart attack and having a pacemaker implanted in your chest might make you think about losing a little weight if you are officially obese. Perhaps it concentrates the mind a little. Or maybe overhearing what the doctor's skinny receptionist called you when she thought you were out of earshot might help!
Obesity should become protective when someone starts to use their stored fat, because human adipose tissue is a health resource which can usefully replace anything with a heart-healthy logo on its plastic wrapping. It doesn't spike glucose! The more weight you have to start with, the longer it takes before the corrosive effect of a low fat diet kicks in. This kicks in when you stop losing weight!
If someone is losing weight on a low fat diet there will obviously come a time when weight loss stops and, at that time, they then simply join the ranks of the initially skinny low-fat eaters but, of course, a fair few of those will be dead by then....
Leaves some space in the queue I guess.