Scientific review confirms superiority of carbohydrate control

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.


References:

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

7 Responses to Scientific review confirms superiority of carbohydrate control

  1. Jackie Bushell 27 July 2007 at 4:22 pm #

    Those of us who are already committed low carb dieters have known for a long time that low carbing spares us from the meagre quantities, poor palatability and constant hunger of low fat/low calorie diets. Not to mention better weight loss and other advantages such as ‘healthier’ blood cholesterol. (As Dr Briffa implies, cholesterol levels are not the villains we have been led to believe, but if lowered cholesterol makes mainstream medicine feel more comfortable about the safety of low carb diets, then hey, who cares!)

    It’s a great pity that the myth that low carb diets are boring, restrictive and unpalatable and that dieters won’t stick to them long term has been allowed to prevail for so long. The only foods that are restricted are fake foods, processed foods full of chemicals, and foods full of unhealthy refined carbohydrates. That leaves heaps of healthy, natural, tasty ‘real’ foods to choose from, and from which to make alternative, healthier versions of the foods and recipes we love to eat! All that is needed is a little ingenuity (or a good low carb cookbook).

    If low carb is ‘undoable’, it’s not because it leaves you hungry, bored or nutritionally deficient. It’s because today’s standard diet is full of high carb, high GI refined wheat, corn and sugar, and it is in the food and catering industries’ interests to keep it that way.

    Those who claim that low carb diets are ‘undoable’ are rejecting the best chance we have of reversing not only the obesity epidemic but the diabetes epidemic too. Enlightened practitioners such as Dr Briffa are to be applauded for helping to counter the ignorance and deliberate misinformation that exists about low carb diets. Our future health depends upon us seeing the standard high carb, high GI diet for what it is – junk that is slowly but surely making us sick.

  2. Tiggy 28 July 2007 at 1:38 am #

    I think there’s a lot of confusion about what should be eaten on a low carb diet. Some low carb diets recommend including some carbs and some include relatively low GI carbs.

    I’m low carbing at the moment and I don’t know if it’s okay to eat smallish amounts of things like wholemeal pasta or granary bread. And where can you get wholemeal pizza?!!

    I’ve even given up Pimms. :-(

    Tiggy.

  3. Andrew Wilmot 28 July 2007 at 11:23 am #

    GLYCEMIC INDEX: WHAT IT MEANS FOR YOU

    The glycemic index is a way of measuring the rate at which carbohydrates are broken down and appear in the blood as simple sugars. Those foods that result in a rapid rise in blood sugar have a high-glycemic index. Carbohydrates that are broken down slowly and cause only a moderate increase in blood sugar have a low-glycemic index. Some carbohydrates fall in between.

    High-glycemic foods provide quick energy, but it is usually short lived and hunger soon returns. Low-glycemic foods provide greater satiety and sustained energy, which makes eating less and losing weight easier.

    High-glycemic diets also have been linked to obesity, type II diabetes, insulin resistance, and heart disease. Virtually all convenience foods and many meal replacement and diet products on the market today are unfortunately, high glycemic.(3)

    3. Foster-Powell K, Holt S, Brand-Miller JC., Am. J. Clin. Nutr. 2002; 76:5-56.

  4. Ian 30 July 2007 at 9:30 am #

    My (amateur) opinion, for what it’s worth:

    Although more enlightened people now recognise that high levels of cholesterol do NOT cause CHD, I’m pretty sure that, since cholesterol is used by the body to repair cellular damage, high levels of this substance are an indicator that the human body is attempting to repair damage caused by a poor diet, i.e. processed foods.

    Therefore, low levels of cholesterol may well indicate a healthy diet.

    To draw an analogy, imagine a police chief investigating a series of fires around a city. Using the logic employed by current dietetic conventional wisdom, he may well detect a pattern and conclude that since fire fighters were present at all the fires, it’s likely that the fires were caused by the fire department. The point is, although there is an association between cholesterol levels and CHD, it’s just bad science to conclude from this that the link is causal.

  5. Steve T 6 August 2007 at 4:09 am #

    As one who has gone on low carb “diets” over the past several years (with great success), I can attest to the success of the approach. One reason for the well documented success might be the restrictive nature of the diet.

    When I go “off” the LC diet, I seem to really go off. I am freed from the restrictions from the carbs to which I have evidently become addicted. I can gain 10lbs in a few short months.

    I’m back on LC and almost welcome the restrictions. All I need to do is avoid sugar, bread, rice, pasta and the like. I will succeed every time. Someone offers me a high-sugar desert and I simply say “no thanks, I’m on a low carb diet”.

    I still crave the carbs, but I know the pounds will literally fall off if I stick to my guns.

    The real test is what happens when I reach my goal. I have proven time and time again that not being on a LC diet is a bad thing. I need a reason to say no to the carbs.

    Anyone else have the same dilemna?

  6. Clare 8 October 2007 at 11:07 pm #

    A bit out of date I know but in case anyone’s reading – the Cochrane review was looking at low GI diets, not necessarily low carb diets. I only checked 2 of the studies they included but one states “The experimental treatment emphasized ad libitum consumption of low-glycemic-index foods, with 45-50% of energy from carbohydrates and 30-35% from fat. The conventional treatment was restricted in energy (250-500 kcal/d deficit) and fat (

  7. Clare 8 October 2007 at 11:09 pm #

    Looks like half the above post is lost, don’t know why – look at the review for the figures.
    Anyway the review has nothing to say about carbohydrate restriction.

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