Monday, June 29, 2009

Fibre: not so great?

Dr. Michael R. Eades rips into fibre, suggesting that the need for regular bowel movements isn't what it's cracked up to be. If he's right (he doesn't really destroy the idea, just suggest that the mechanism behind it seems strange), then it would support the Paleo Diet idea that grains (which are high in fibre) are bad.

Hmmm, might stop adding the psyllium husk to my muesli ...

Saturday, June 27, 2009

Paleo Diet

I've been doing lots of reading on diet lately. I came to the Paleo Diet via two paths: my boss has successfully lost a good twenty kilos by adhering to it, and it's a logical extension of the grain-free diet I've been testing out.

What I like about the Paleo Diet is that it is not based on our rather hazy understanding of the biochemistry of the human body, but on our understanding of evolution. It's simple: for the vast bulk of the history of the human race (say 1 million years), we lived as hunter-gatherers. It is only in the last 10,000 years (if that) that we've had agriculture and have eaten the foods which that has provided. The Paleo Diet is based on the premise that our bodies have evolved to eat a hunter-gatherer diet, but not an agricultural diet. One can further surmise that the many "diseases of civilisation" may be rooted in the current dependence on a diet to which our bodies are not accustomed.

So, what did a hunter-gatherer diet look like? Apparently, they got about 45-65% (by energy) of their food from meat (indeed, the Inuit's complete diet consisted of meat). That is: hunted game, eggs, fish and insects (witchetty grubs and bogong moths!). The rest was plant food such as leaves and roots, and any fruit and nuts that were in season. Obviously the exact food varied from region to region, and from season to season. What was notably absent was food high in carbohydrates, such as grains, legumes and potatoes.

By comparison, the modern diet is overly dependent on high-carb foods and sugar. Obesity and diabetes are an obvious result of that. I'm not sure of the mechanism, but high-carb, low-fat diets seem be bad for heart disease.

Mark Sisson provides an overview of how much carbohydrate we should eat. The typical modern diet consists of about 150-300g of carbohydrate per day, with the upper end leading to rapid weight gain and disease risk. He suggests aiming for 100-150g of carbohydrate per day on a Paleo Diet. Going for less makes it easy to lose weight, particularly under 50g/day (where your metabolism starts doing some interesting things!).

So how much protein? Mark Sisson suggests you aim for a minimum 0.5g/lb of lean body mass (i.e. your weight, minus the fat), and 0.7/g to 0.8g/lb if you're are moderately active. So that's 1.1-1.7 g/kg of lean body mass. I weigh 68kg, and would guess my lean body mass was about 60kg, so I would need to aim for 65-100g of protein. Thanks to CFS, I'm not very active at all so the lower figure will do. Conventional wisdom says to aim for 0.8g/kg of body mass, so the Paleo Diet is hitting the protein a fair bit harder.

The energy balance comes from fat - and it needn't be polyunsaturated fat. Saturated fat is fine, and omega-3 fats are best. I'll write more on fats later.

Next post, I'll do breakdown my typical daily diet and work out what I need to change to go Paleo.

Monday, June 22, 2009

Magnesium

I remember in high school chemistry when we used to burn little strips of magnesium. A star of bright light ensued! But apparently magnesium is an important nutritional mineral. It is involved in quite a lot of important metabolic reactions.

Apparently, most people are magnesium deficient, thanks to the modern-day diet (most Americans get about half the RDI). It is also often used to treat CFS, with some success.

Mangan has an interesting post on magnesium and depression. Mg deficiency leads to increased inflammation, which can be an underlying cause for a great number of diseases. Oh, and here is an absurdly detailed page on magnesium and depression.

I found this page gives a useful overview on how best to supplement. In short:
  • Use a magnesium chelate, as these are best absorbed.
  • Don't take it all in one go - spread it out during the day, as there is a limit to how much you can absorb at a time.
  • RDI is 400mg/day, but this is a bare minimum. Aim for 5-10mg/day of ideal body weight. So for me, that would be 350-700mg/day, and I would go for the higher number because of my CFS (which may implicate Mg deficiency).
When I finish this grain-free experiment, I'll give magnesium a go. Probably about 200mg three times a day to start with.