As some people have noted on comments here previously, one of the key advantages of intermittent fasting diets is their apparent impact on Insulin-like Growth Factor (IGF-1). It is the lowering of the IGF-1 levels that is meant to be behind the cancer-reducing properties of intermittent fasting diets like ADF. In the Michael Mosley doco, Eat, Fast and Live Longer, he placed great emphasis on the extent to which the 5:2 diet might reduce his IGF-1 levels.
I am not sure what evidence there is that links IGF-1 levels to cancer . One of the main arguments seems to be that the people with Laron Syndrome (a type of dwarfism), who have really low levels of IGF-1, don’t get cancer (they don’t get diabetes either). The main study on this related to a group of people in Ecuador that Dr Mosley referred to in his documentary. This was a 22 year study published in 2011 that monitored a group of 99 Ecuadorians with Laron syndrome and compared them close relatives who were of regular height. Over the period of the study about 20 per cent of the relatives died of cancer, but none of the people with Laron-syndrome got cancer.
Unfortunately, the people with Laron syndrome in the study don’t actually seem to live any longer. In the study, their common killers were age-related diseases such as heart disease and stroke. Compared with their relatives of regular height, they also “died much more frequently from accidents, alcohol-related causes, and convulsive disorders.” I guess not getting sick makes them feel bulletproof!?
What got me thinking about this again was that font of knowledge, the Daily Mail. They had a very good article in today’s paper describing the journalist, Anna Pursglove’s 5:2 diet. At the start she had her IGF-1 levels tested and then had it re-tested a month later when it is lower by a “statistically significant” amount.
So I was wondering if anyone else has had their IGF-1 levels tested/re-tested and what were the outcomes? Has anyone done any looking into the science behind IGF-1 levels and cancer?
It also relates to another discussion about high protein diets, because from the little I have read, diets higher in protein tend to promote IGF-1 levels. Now, since going on ADF I have probably increased my protein intake relative to my carbohydrate intake, particularly on fast days (although while it is a higher proportion, because of the small number of calories it is still not a large amount). Does this mean that having a lower-carbohydrate, higher protein diet is counteracting the cancer fighting benefits of the ADF regime. Any thoughts??