obesity, calories, starch and saturated fat

The National Obesity Forum have criticized Public Health England and their Eatwell Guide. There are two polarized opinions expressed here. One side says that obesity is about calories in (from food) and calories out (through exercise). The other side say that calories have nothing to do with obesity.

One side says all starchy foods are good. The other side says all starchy foods are bad.

One side says all saturated fats are bad. The other side says all saturated fats are good.

I think both sides should be ashamed of themselves. The public are confused. Both side are treating all starchy foods as if they are the same. They aren't. Pasta has a low glycemic index, and potatoes have a high glycemic index. That means that pasta eaten in moderation is unlikely to contribute towards the development of diabetes. The starch in potatoes is digested quickly into glucose and pushes up blood glucose and insulin levels soon after eating.

We now know that the fat in cheese, despite being saturated fat, is unlikely to contribute towards heart disease. That's good for me because I like cheese. If I liked burgers though, the news is not so good. We are unsure if beef fat will contribute towards heart disease. All fat can contribute towards obesity though because it is calorie-dense. Now I realize that not all calories are the same. 100 calories-worth of sugar will be treated differently by the body that 100 calories-worth of olive oil. To say though that obesity has nothing to do with calories can't be right.

Why do both The National Obesity Forum and Public Health England have so little to say about the glycemic index? Perhaps they think ordinary people can't take it in. Maybe it seems counter-intuitive (why would starch from pasta and potatoes be so different?). If you like to think of food as something natural and not worry about the science too much then don't like to talk about indexes.

It's not rocket science. They should both get their act together.

Michael Mosley, the Daily Mail, and saturated fat

When I was listening to late-night radio recently they started to discuss an article in the Daily Mail about saturated fat and heart disease. The article was written by Dr Michael Mosley. The presenter said that he didn't realize that pasta and potatoes are bad for you.

I took a good look at the article because I thought what he wrote is wrong. This is what he wrote.

"My response was to exercise more but it had little effect. I was eating less fat, but compensating with starchy pasta and potatoes. What I hadn't appreciated is the way these foods act on your body. A boiled potato will push your blood glucose up almost as fast as a tablespoon of sugar, since it is rapidly digested.
Ironically, we now know that if you eat that potato with butter, the fat will slow absorption and the blood sugar peak will be less extreme.
Rapid spikes in glucose force your pancreas to pump out insulin, which drives it back down, but can leave you hungry again a few hours later.
Carbohydrates are also less satiating than fat or protein. So you eat more and the weight creeps up."

Pasta has a low Glycemic Index which means that it doesn't push your blood glucose up. So he's got that wrong. As for potatoes, some potatoes have a high GI and some a low GI. New potatoes have a low or moderate GI. Nowhere in the article does he mention the Glycemic Index. He doesn't seem to understand what it is.

If you have potato with olive oil it will have a lower GI. Extra virgin olive oil from Lidl or Aldi are cheaper than butter. Despite the recent evidence about the relationship between saturated fats and heart disease, it still seems that olive oil is healthier than butter.

It has never been the case that health advisors have said all fats are bad and all carbohydrates are good. We have known for a long time that olive oil is a healthy oil as is fish oil. So why is Dr Michael Mosley trying to make out that this is what people were lead to believe? Is it because he seems to want to make the opposite argument that all fats are good and all carbohydrates are bad? That is what he seems to be saying.

It is true that protein can suppress appetite. It is not true though that low GI starchy foods like pasta and long-grain rice are less satiating than fat. So I don't agree that people are likely to put on weight by eating pasta, long-grain rice or porridge instead of butter. In any case they can have olive oil instead of butter. So butter is still not the best option.

He mentions research that shows olive oil and fish oil are healthy, and then goes on to mention the recent research funded by the British Heart Foundation and published this year. Mosley says 'the researchers found no evidence that saturated fats cause heart disease'.

What the evidence from this study seems to be saying is that we have to look at each individual fatty acid instead of looking at groups of fatty acids such as saturated, monounsaturated, omega-6 and omega-3. DHA and EPA, two long-chain omega-3 fatty acids found in fish oil, are both linked to lower heart risk. No surprise there. But so is AA, which is an omega-6 fatty acid.

At least, when these three fatty acids are found in good quantities in the blood, there is a lower heart risk. Yet the study 'also found no significant link between heart risk and intake of total monounsaturated fatty acids, long-chain omega-3 and omega-6 polyunsaturated fatty acids'. Which is curious. If you have more of them in your blood you are less likely to die of a heart attack, and yet consuming DHA and EPA in the form of fish or fish oil doesn't seem to have a beneficial effect? What are we to make of this?

"They also looked in detail at saturated fatty acids. Here, they found some weak links between bloodstream levels of palmitic and stearic acids (predominantly found in palm oil and animal fats, respectively) and heart disease, but blood levels of the dairy fat margaric acid appeared to significantly reduce heart risk."

It could well be that fat from most meat is bad for you but fat from milk isn't. Pork fat has more monounsaturated fat that beef fat and so is considered healthier. Goose fat might be healthier too. Coconut oil, despite being saturated, seems to be healthy. So the question is not fat versus carbohydrate. We should be consuming good fats and good carbohydrates and refraining from bad fats and bad carbohydrates. I get most of my calories from low GI starches such as long-grain rice and pasta. If people want to get most of their calories from both low GI starches and healthy fats such as olive oil, fish oil, and avocados then that's good too. The fat in cheese might be good, but I don't think burgers are something I would want to consume every day. But then I'm not going to consume margarine or sunflower oil either.

It's not a question of fat v carbohydrate, and it's not a question of saturated fat v polyunsaturated fat. We know that lots of polyunsaturated fat if it is nearly all omega-6 isn't good for health. There should be a balance between omega-6 and omega-3 which means we should have less omega-6 (from vegetable oils like sunflower oil) and more omega-3 (especially long-chain omega-3 from fish). Now it seems that some saturated fatty acids can be good too.

So when the research shows that cutting saturated fat per se doesn't do anything for our health and that consuming more polyunsaturated fat per se doesn't do anything for our health either, that doesn't mean that there aren't some saturates we should avoid or that there aren't some polyunsaturates we should have more of.

There's an interesting New Scientist article that says a lot of the same things as I'm saying.