How dietary carbohydrates cause weight gain

Part 2: 'Healthy eating' stops you losing weight

So far we have only considered half of the obesity problem. The other half is: Having put weight on, you now need to get it off again. Here again 'healthy eating' hampers your efforts because eating a carbohydrate-based diet also stops you from losing weight.

If you are overweight, what is it that you actually want to lose? That's not as silly a question you might think. You don't want to lose weight — you can do that by having a leg amputated; what you really want to lose is fat, right?

The point is that, to lose fat, your body must use that fat as a fuel; there is no other way. And the only way your body will use its stored fat as a fuel is if you force it to. That means depriving it of its present supply of fuel — the blood sugar, glucose — so that it has no choice in the matter.

There are two ways to cut your body's glucose supply:

you either starve — which is what low-calorie, low-fat dieting is, or

you reduce the starches and sugars from which glucose is made and make it up with a source of a different fuel — fat.

The latter approach has two advantages over the traditional calorie-controlled approach: it means that you no longer have to go hungry and, by feeding your body on fats, it will stop trying to find glucose and change over naturally to using its own stored fat. This is by far the easiest way because:

'In the presence of dietary carbohydrate, the preferred fuel is glucose and the capacity to mobilize fat is limited. Factors that increase blood glucose during dieting may stimulate insulin release and all the metabolic sequelae of circulating insulin. Fatty acid synthesis is activated and lipolysis is profoundly inhibited by insulin even at very low concentrations of the hormone.' [1]

This means that, if you eat a carbohydrate-based, low-fat diet, you force your body into a fat-making (fatty acid synthesis) mode, not a fat-using (lipolysis) mode. The study that extract was taken from was published in 1992 but it merely confirmed what had been demonstrated decades before (but forgotten) when Dr. Michael Somogyi published an article in which he showed clearly that 'car­bohydrates . . . inhibit the burning of fats'.[2]

1. Kreitzman SN. Factors influencing body composition during very-low-calorie diets. Am J Clin Nutr 1992; 56: 217S-23S

2. Somogyi M. Studies of arteriovenous differences in blood sugar; II. Effect of hypoglycemia on the rate of extrahepatic glucose assimilation. J Biolog Chem 1948; 174: 597-604.