Eating three low-carb meals within 24 hours lowers post-meal insulin resistance by more than 30 per cent, according to a study at the University of Michigan.
The study’s author claimed it showed that a ‘simple dietary modification’ could block the path to diabetes (but see our expert analysis below).
The research, published in the journal Plos One, also revealed that two hours of moderate-intensity exercise, which was believed to lower insulin resistance and blood sugar levels, has no impact. Blood sugar levels actually increased after exercise.
The researchers said that high-carb meals sustain insulin resistance, a condition that leads to high blood pressure and diabetes.
During the study, 32 post-menopausal women were divided into four groups and given meals with either 30 or 60 per cent carbohydrate content. These groups were further divided between those who did moderate-intensity exercise before eating and those who didn’t.
The low-carb group showed a reduction in insulin resistance after the third meal in the evening, but the high-carb group sustained high post-meal insulin. The diet of the ‘high-carb’ group was within carbohydrate limits recommended by the NHS and America’s Department of Agriculture.
The study’s lead author, Katarina Borer, said: ‘What is remarkable about our findings is that they show that a simple dietary modification of reducing the carbohydrate content of the meals can, within a day, protect against development of insulin resistance and block the path toward development of pre-diabetes, while sustained intake of high carbohydrate diets, as shown in the two mentioned studies, lead to increased fasting insulin secretion and resistance.
‘And even more surprising and amazing is that exercise before the meals made the subjects more carbohydrate intolerant — that is, it increased evening blood sugar levels.’
This study has a few major flaws. First, we know that there will be a spike in insulin after eating a carbohydrate-heavy meal, but how this affects the long-term likelihood of developing diabetes is hugely complex and based on many individual lifestyle considerations as well as other predisposing factors. This simply cannot be extrapolated from the data presented here. In addition, the entire study group is 32 post-menopausal women aged 50 to 65 — a very small and specific group. Although the authors argue that this, as well as the short-term nature of the study, is mitigated by longer-term results being similar in other previous studies, this does make it very difficult to draw any strong conclusions at all, let alone to apply them at a population level.
Research score: 1/5