Scientific review confirms superiority of carbohydrate control

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Earlier this month I provided a round-up of the evidence which suggests that carbohydrate control is generally more effective for the purposes of weight loss than the more traditionally-advised low-fat diet. Not long after this, on the 18th July to be precise, the research group known as the Cochrane Collaboration published its own assessment of lower=carb diets on-line.

This review assessed results of trial in which the effects of low glycaemic index (GI) or low glycaemic load (GL) diets had been compared with ‘control’ diets which restricted calories and/or fat. Six trials (lasting 5 weeks to 6 months) involving overweight or obese men and women were used in the review.

Overall, the low-GI/GL dieters lost more weight (an average of about 2.5 lbs), fat mass, and ended up with a lower body mass index (BMI). All of these results were statistically significant.

In addition, low-carbers ended up saw greater reductions in their total cholesterol level and well as level of the LDL (low density lipoprotein) cholesterol ” often dubbed ‘unhealthy’ cholesterol.

Personally, I don’t care much about cholesterol levels, and feel they have been over-stated as a factor in health. Nevertheless, I recognise that most health professionals would see the improved cholesterol levels prompted by carb-restriction would be seen as a positive health boon.

The authors of this study end up concluding that lowering the GL of the diet appears to be an effective method of promoting weight loss and improving lipid profiles and can simply be incorporated into a person’s lifestyle.

The authors’ words about this approach being able to be simply incorporated into one’s lifestyle is relevant, because it stands to reason that a ‘doable’ dietary approaches are generally going to have better traction in the long term.

This is important because, to my mind, the real winners in the ‘diet wars’ will be those that bringing lasting success. Outside of the rarefied and contrived environment of formal scientific study, I have found carb control to be one approach to healthy eating that many individuals find they actually can get along with in the long term. One reason for this relates to the fact that it’s principles are generally easy to grasp and put into practice.

But there’s another major reason why carb-controlled eating is sustainable: its basic premise is that the important thing is not the quantity of what is eaten, but its quality. Many low-carb regimes (and in fact the ones assessed in the recent Cochrane review) do not restrict the amount of food that individuals can eat. Which means they are less likely to get hungry. Which makes things a helluva lot easier for those who are looking to the long term.

And now for the kicker: individuals who employ carb-control not only generally need not go hungry, but often report eating less than they ordinarily do quite naturally. One reason for this may relate to the fact that the a food’s GI seems to have a profound effect on subsequent appetite. Basically, the higher a food’s GI, the less satisfying it tends to be. Of 20 studies published between 1977 and 1999, 16 showed that low GI foods promoted the satisfaction derived from that meal and/or reduced subsequent hunger [2]. Overall, the results of the studies show that an increase in the GI by 50 per cent reduces the satisfaction it gives by about 50 per cent.

Some detractors of low-carb eating will claim that this way of eating is unworkable and unsustainable in the long term. However, the absence of restriction and its ability to quell appetite mean that with carb-control, satisfaction is more likely to be guaranteed.


1. Thomas DE, et al. Low glycaemic index or low glycaemic load diets for overweight and obesity. Cochrane Library 18 July 2007 [Epub]

2. Roberts SB. High-glycemic index foods, hunger, and obesity: is there a connection? Nutrition Review 2000 58:163-169

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