May 19, 2018

expert reaction to unpublished poster presentation on diabetes and fasting as presented at the European Society of Endocrinology annual meeting, ECE 2018

Researchers presenting at the European Society of Endocrinology annual meeting, ECE 2018, discuss research that investigates intermittent fasting and insulin resistance in rats.

Dr Nicola Guess, Lecturer in Nutritional Sciences at King’s College London, said:

“Firstly, it’s important to bear in mind there are important differences between rodents and humans – particularly with regard to diet. For example, a high fat diet causes insulin resistance in rats but it does not appear to in humans.

“The exact method is unclear from the abstract, but if the rats were fasted for one day, this is equivalent to an approximately 3 to 4 week fast in humans! So it’s not applicable to the 24-hour or 48-hour fasts practised by humans on common fasting diets.

“We certainly need more studies to understand the impact of fasting diets on the underlying factors which can lead cause type 2 diabetes, but this preliminary data in rats is not a cause for concern.

“Most of the data we have suggests that fasting for one or two days can help people manage their weight but it’s currently unclear whether there are any particular benefits from doing this.”

Dr Simon Cork, Research Fellow in the Division of Diabetes, Endocrinology and Metabolism at Imperial College London, said:

“There are a few important caveats to this study.  The study was performed in rats, so more research is needed to understand whether these results are applicable in humans.  The ‘diabetes’ was assessed by looking at markers associated with insulin resistance, which doesn’t actually mean that the animals had become diabetic; it points towards that possibility, but there are better methods to assess whether an animal has become diabetic.

“We know that the body responds robustly to any diet. A drop in weight is essentially perceived by the body as that person entering a famine, and so the body responds by conserving energy, usually in the form of fat. The results from this study show that, although the animals did lose body weight following intermittent fasting, they actually had increased fat tissue and had lost muscle mass. One reaction to starvation can be insulin resistance (a hallmark of type 2 diabetes). Since elevated insulin levels associated with insulin resistance/type 2 diabetes promote weight gain, this would be advantageous to those likely to experience famine. Unfortunately, this response is redundant in modern times, when famine is all but non-existent.

“These results are interesting, but not surprising. We know that any diet which reduces calorie intake is unlikely to result in long-term weight loss, with many actually resulting in greater weight gain than before the diet started.”

* Abstract title: ‘Intermittent fasting for three months decreases pancreatic islet mass and increases insulin resistance in Wistar rats” by Ana Cláudia Munhoz Bonassa and Angelo Rafael Carpinelli.  This is a conference talk that was discussed at the European Society of Endocrinology annual meeting ECE 2018 on Saturday 19 May 2018.  There is no paper as this is not published work.

Declared interests

None received.