There is a scientific argument raging about whether restricting calorie intake in humans has any health benefits or not. Another study that adds to the fray suggests less calories leads to a better memory.
It is clear in mice that calorie restriction leads to a longer life and a reduction in the diseases of aging such as heart disease. However, in humans the picture is not clear. Part of the problem is that it hard to get most humans to significantly restrict their food intake for long periods of time.
A new study suggests that cutting back on calories may improve memory. Participants in the study were normal to overweight, with a mean age of 60.5 years. They were divided into three groups. One group cut their calories by 30%, relative to what they had been eating before (mainly by smaller portion sizes), a second group increased the amount of unsaturated fats by 20%, reducing their intake of saturated fat so that total fat intake did not change, and the third group made no dietary changes.
All participants were tested at the start of the study and three months later. Only those on the calorie restricted diet showed an increase in verbal memory scores. They were tested for working memory, attention and delayed memory. The delayed memory test involved learning as many words as possible from a list of 15 and then seeing how many could be recalled 30 minutes later.
Interestingly, increases in memory correlated with a decrease in levels of both fasting insulin and hsCRP. Decreased fasting insulin indicates a greater insulin sensitivity, which means better control of blood glucose. hsCRP is an indicator of inflammation and is used as a marker for increased risk of atherosclerosis (hardening of the arteries), with higher levels being used as an indicator of risk of cardiovascular disease. This suggests that lower levels of inflammation may be good for memory and that for some reason insulin sensitivity may be related to memory.
Other studies in humans have not shown any changes in memory ability with calorie restriction, but as usual all studies are small and they used younger study populations, were done in different ways with different testing.
If calorie restriction really is good for your health, the problem is how to eat less. I would like to see a big study in humans that looks at the effects of periodic short fasts on memory. A study in mice showed that memory is improved on a fasting regime. It has been shown in humans that fasting improves insulin sensitivity and cardiovascular health (see the post Occasional Short Fasts May Be Healthy), so it may help memory too. Most people find it easier to not eat for most or of a day (without compensating by eating a lot when having the first meal) rather than cut back all the time.
It is food for thought!
photo credit: Jacob Bøtter
[tags]calories, memory, fasts, fasting, calorie restriction, insulin hsCRP[/tags]
