Diets: Low carb vs. Low fat vs. Low GI


Back in March I did a post called “Sugar is evil“, looking at why sugar is so bad, about GI and how to make food choices to keep your insulin levels stable. I’ve just been reading about some research which has just been published in the Journal of the American Medical Association which supports the notion that low glycemic index diets are the way forward. From an article in the NY Timesbr />

The study put three groups of people on diets to lose 10 to 15 percent of their body weight. They assigned each of the dieters, in random order, to follow four weeks each of three diets with the same number of calories. One was a standard low-fat diet: 60 percent carbohydrates – with an emphasis on fruits, vegetables and whole grains (but not unprocessed ones) – 20 percent from protein and 20 percent from fat. This is the low-fat diet that has been reigning “wisdom” for the last 30 years or more. 

Another was an ultra-low-carb diet, of 10 percent of calories from carbs, 60 percent from fat and 30 percent from protein. And the third was a low glycemic diet, with 40 percent carbs — minimally processed grains, fruit, vegetables and legumes — 40 percent fat and 20 percent protein. 

The results were impressive. Those on the ultra-low carb diet burned 350 calories more per day – the equivalent of an hour of moderate exercise – than those on the standard low-fat diet. Those on the low-glycemic diet burned 150 calories more, roughly equivalent to an hour of light exercise.

You can read a bit more on the Science Daily site.

Protein is believed in some camps that the 4kcal/g calorie count it has been allocated is actually too high, because it doesn’t account for the higher amount of energy which is expended as it’s digested, which may account for such a dramatic increase in calorie burn (I can’t find the links for this right now – will add them later). It is also the most satiating of the macronutrients, dulling hunger due in part to the fact that it doesn’t spike insulin and elevates leptin, the hormone that controls hunger (as opposed to carbohydrates that do the opposite). You can read more on this on Charles Poliquin’s blog

The reason that the article concludes to favour low GI diets is because very high-protein diets can trigger release of the stress hormone cortisol. There are obviously other potentially negative effects, such as the consumption of a relatively high amount of saturated fat (I bet I’m not alone in having heard Atkin’s freaks banging on about how much bacon they eat!). The article concludes, and I pretty much agree, that unprocessed and unrefined carbs are worth adding for a more moderate yet still improved calorie burn.

Personally I follow quite a high protein diet – I shoot for 0.75 – 1g of protein per pound of bodyweight (I’ll let you take a guess and do the maths) which I think is a decent level for someone who does a lot of strength training. I get the most volume of carbs during the day from fruit and vegetables, but include a heavy serving of carbs, mainly sweets potatoes at the moment – yum – in my post-workout meal. Obviously this is going to be different on my vegan days (next one tomorrow).

Finally, I will leve you with a link to a blog post about “Hybrid diets”, which is just a guy talking about how he’s combined elements from different diets to create something that works for him. After all, along with keeping calories in check and insulin stable, that is one of the single most important factors in choosing how you eat (and, for that matter, how you exercise, work, live etc.!)

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2 Responses

  1. Fi says:

    OMG those are some seriously freaky thighs. Although it’s the stat about them being 4 inches wider than Victoria Beckham’s waist that really makes the article.