Refined carbohydrates are detrimental to the health because they causes a deterioration in glucose homeostasis. In particular, carbohydrates that are devoid of their original fibre cause liver overload syndrome, and an increase in the production of fatty acids through the de novo lipogenesis pathway. These lipids may be a primary driver of insulin resistance because they accumulate in hepatic tissues and skeletal muscle where they cause central and peripheral insulin resistance, respectively. The advice for overweight individuals to avoid fat and cholesterol containing protein sources of food, and instead increase the carbohydrate content of the diet has only made these individuals fatter because the carbohydrate foods chosen are often refined and this further compound metabolic dysfunction. The same can be said for type 2 diabetics who are often advised to eat refined crystalline fructose, which in nutritional circles is now considered public enemy number one when it comes to causing insulin resistance and central adiposity.
One of the main problems with energy restrictive diets comes in the refeeding phase. The weight loss phase of such diets can often be comprised of more than 50 % skeletal muscle. This loss of muscle tissue lowers the resting metabolic rate and it is this reason that refeeding often causes fat regain and a return to the previous body weight. However, while fat accounts for only around half of the initial weight loss, almost all of the weight regained in such regimens is fat. Therefore energy restrictive diets gradually cause a deterioration in body composition. The detrimental effects of feeding are exacerbated if a Western style diet is consumed during this period, particularly if sucrose is included in the diet. Sucrose appears to cause an increased deposition of fat tissue during refeeding when it comprises a significant portion of the diet, compared to diets that are lower in refined carbohydrates. Experiments of rats attest to the ability of sucrose to induce significant adipose tissue growth during refeeding phases of low calorie diets.
For example, in one study1 a group of rats were fasted to induce weight loss and then refed either a high carbohydrate diet containing sucrose or the same high carbohydrate diet but with a glucosidase inhibitor to delay sucrose digestion and prevent rapid glucose reabsorption. The high carbohydrate diet containing sucrose caused an increase in the insulin response to glucose during refeeding and caused a significant increase in adipocyte size during refeeding. However, the addition of a glucosidase inhibitor to the diet caused a delay in energy accumulation during refeeding and this was represented in significantly lower levels of muscle and liver glycogen as well as lower levels of body fat accumulation. These results therefore suggest that consuming foods containing high amounts of sucrose causes detrimental fat accumulation, and that delaying the absorption of the sucrose might reduce the accumulation of body fat and prevent some of the damage seen in the refeeding phase of low calorie diets.
Dr Robert Barrington’s Nutritional Recommendation: Legumes contain glucosidase inhibitors like the one used in this study (acarbose), and this may explain their weight loss properties. These inhibitors delay the absorption of glucose and thus have favourable glycaemic effects. Legumes are also rich in fibre, and this may also play a role at improving glycaemic control. Consuming refined crystalline sucrose as might be found in processed ‘low fat’ supermarket foods are detrimental to any weight loss plan but might be particularly problematic during the refeeding phase.
RdB
