Could Fasting Be The Key To Long Life And Good Health?
Fad diets are nothing new to us. We hear about the new amazing way that this celebrity got a ‘beach-bod’, how that one shifted the baby weight, and how that one looks on the catwalk. We are probably pretty much immune to the latest crazes, I for one have started to glaze over when I hear a fad-diet story. That is how it was for me when I first heard about the ‘fast diet’.
It is a calorie restrictive plan, where you eat normally for 5 days per week, and seriously limit your calorific intake for the other two days. I didn’t pay much attention when it came up in conversation, but the headlines surrounding Intermittent Fasting have not gone away…and in fact they have piqued my interest. I have seen articles ranging from claims about heart and cardiovascular health, reduced risk of developing cancer, cell repair and longevity, and so decided to approach this idea with an open mind,
When we consider that fasting may be closer to the way that our ancestors always used to eat, it takes on a new meaning. It is unlikely that the stone-age man ate 3 square meals each and every day – and so we could assume that humans evolved being used to eating feasts when food was available, and surviving on what was available at other times. Could these cycles of feast and famine be the way we are designed to eat?
Fasting is also recommended by a number of religions and spiritual practitioners, as a way to get in touch with the soul and even access higher realms. There are Buddhist monks who spend weeks without eating – although I am not sure that they are not scientifically measured in their fasting.
Intermittent Fasting, or IF can take many forms, but in essence, it is a system of shifting between periods of normal eating and periods of restricted (or zero) calorie intake. It can be five days of eating, two days of fasting each week as mentioned above, or five days of fasting each month, or even 18 hours of fasting each day.
It is up to individuals to decide on a system that is most comfortable to them, without leaving them feeling very hungry, weak or lethargic. The best plan is one that you can stick to without cheating, so that is what should be the most important thing to consider.
There have been a number of studies conducted into the area to assess the impact of IF on health, the majority of which have researched rats. The results have been varied, depending on a number of factors including gender and weight. Still the positive benefits are very interesting and worth looking into.
Studies have determined that reducing calories by 30-40% can extend life span by 1/3 or more in some species of animal, including fruit flies and rodents. As well as increasing life span, the risks of chronic disease in old age is also lessened. But the results are not so clear when it comes to humans.
However, the overall feeling is that IF gives the same benefits as long term calorie restriction, with some additional bonuses. So aside from not feeling hungry all of the time, there may be further positive side effects from fasting.
There is reduced loss of muscle mass and bone mineral density from intermittent fasting compared with long term calorie restriction too.
This is another grey area – not least because the majority of research has been conducted on rodents. However, some authors on the subject say that the fast days should consist of only water, while others suggest a quarter of the usual calories are consumed.
Some write that you can eat whatever you like on the feast days, as long as you don’t gorge, and end up eating enough for the fast days too. However, I would lean towards a more sensible approach.
For the famine days, it is clear that calories need to be restricted, in order to trigger the starvation response, and give your body a break from digesting, so they can be as restrictive as you can bear without cheating. I would be tempted to include black coffee….. I would be careful not to over indulge in fruit on the fast days. But the feast days in my opinion should still consist of generally healthy food. Going overboard and gorging on processed foods for all of the feast days would surely counteract the benefit of the fast days.
So, onto the studies and the reported benefits of the feast-famine cycle.
A study from 1945 by Robertson, Marston and Walters looked at the impact of fasting mice for 2 days in 7.
They studied “the effect of intermittent fasting on the life span of mice. In that study, twenty-four male and twenty-four female mice were fasted 2 successive days in 7. The average life span of the fasted males was found to be 745 days while that of twenty-four controls was 712 days. The average for the fasted females was 819 days while that of twenty-four control females was 773 days”.
It makes sense that IF should increase longevity, when it is widely documented that reduced calorie intake over time has this effect. The increased life span could be connected to a reduction in a number of health factors that are also possibly improved through IF – they are addressed here in turn.
This study by Heilbronn et al looked at alternate day fasting in non-obese humans. They put 16 participants, half male and half female, on a diet where they fasted every other day for 22 days. Body weight, body composition, insulin levels and more were measured.
Overall the subjects lost between 0.5 – 2.5% of their starting body weight, and their fat mass fell by as much as 4%. Fasting insulin was also found to have decreased. It was suggested that alternate-day fasting was a feasible weight loss method in non-obese adults, despite the fact that hunger levels remained steady on the fasting days even over time.
We mentioned insulin levels in the study above. It is one of the key factors in weight and long term health, as it is connected to many chronic diseases that contribute to life span.
The fact that IF increases the body’s sensitivity to insulin is therefore very beneficial. It means that our cells require a smaller amount of insulin in order to react as they need to. Insulin resistance can be a pre-requisite to a number of unpleasant diseases., causing it to turn to fat, rather than sugar as it’s primary fuel. Ketones are released when the body burns fat, and the human brain runs more efficiently on these than glucose.
Therefore, if IF could help to rebalance the body it is worth continuing research into this lifestyle.
I have mentioned ‘chronic disease’ a few times now, and so wanted to demonstrate exactly what is meant by this in the context of Intermittent Fasting and the positive impact it can have on our long term health.
A study by Valter D. Longo et al, of the FIRC Institute of Molecular Oncology claims to have “demonstrated the first anti-aging, healthspan-promoting intervention that doctors could feasibly recommend for patients”.
“Although the clinical results will require confirmation by a larger randomized trial, the effects of FMD cycles on biomarkers/risk factors for aging, cancer, diabetes, and CVD, coupled with the very high compliance to the diet and its safety, indicate that this periodic dietary strategy has high potential to be effective in promoting human healthspan.”
Furthermore, this study by Varady et al looked at alternate-day fasting as it’s potential to act as a cardio-protector in obese adults. On this study, participants ate 25% of their energy needs in calories on the fast day, and what ever they chose on the following day. The trial lasted for 10 weeks, and followed 12 obese women and 4 obese men. They found that body weight and percentage body weight decreased over the course of the study. In addition, cholesterol, LDL cholesterol, and triacylglycerols in their blood also reduced. Systolic blood pressure was also decreased.
“These findings suggest that ADF (alternate day fasting) is a viable diet option to help obese individuals lose weight and decrease CAD (cardiovascular disease) risk.”
I mentioned earlier that eating a fat based diet released ketones, which is the brain’s preferred choice of fuel – but the benefits of IF on the brain may be even further reaching than that.
Mark Mattson has recently released research which shows that the production of a protein called Brain-derived neurotrohic factor (BDNF) is also boosted by fasting. This protein supports fatigued neurons, preventing them from dying. It stimulates the brain stem cells to convert into new neurone and other chemical processes that benefit the grey matter.
This has been connected to reduced chances of developing dementia such as Alzheimer’s and Parkinson’s disease. Alternate day fasting has the potential to boost BDNF by 50 to 400%!
It has also been suggested by Mattson’s research that remaining in the ‘feast’ cycle, without allowing for times of ‘famine’ in our diets, prevents a lot of the repair and rejuvenation work that our bodies need to undertake from time to time. IF allows the body to set aside energy for ‘autophagy’ which he describes as a garbage disposal for our cells! They can push out the left over bits of molecules which are discarded after various cellular reactions.
IF is also connected to an increase in the number of chaperone proteins in the body – which in simple terms, help to assemble new molecules correctly.
In 2007, Mattson et al reported that they found a link between alternate day fasting and a reduction in asthma and other forms of inflammation. They studied nine overweight adults who were known to suffer from asthma. The participants fasted every other day for two months, and the results showed a significant improvement in their condition.
A study in 2011 suggested that rats who were subjected to intermittent fasting actually had an increase in the amount of glucose in their blood. They also demonstrated increased oxidisation in their cells and some showed a stiffness in their heart muscle.
An additional concern is that those who fast intermittently may gorge once it is over, in order to ‘compensate’ for the lost food and in response to their ravenous hunger. This may well undo the positive benefits of consuming reduced calories overall.
A very important factor to be aware of in some of the studies that have been discussed here, is that there has been reported a marked difference between the response of males and females to IF – with women demonstrating less favourable results in some instances.
In a study by Martin et al, which looked at the “Sex-Dependent Metabolic, Neuroendocrine, and Cognitive Responses to Dietary Energy Restriction and Excess”, they watched the responses of groups of male and female rats to various energy intakes over the course of six months.
They found a marked difference between the genders when they reduced calorie intake to 60% of the energy requirements.
In response to 40% CR (calorie restriction), females became emaciated, ceased cycling, underwent endocrine masculinization, exhibited a heightened stress response, increased their spontaneous activity, improved their learning and memory, and maintained elevated levels of circulating brain-derived neurotrophic factor.
In contrast, males on 40% CR maintained a higher body weight than the 40% CR females and did not change their activity levels as significantly as the 40% CR females. Additionally, there was no significant change in the cognitive ability of the males on the 40% CR diet.
The study found that the two genders reacted in a similar way when it came to cholesterol, insulin and other energy-regulating hormones. The study also found that in rodents particularly, “severe calorie restriction inhibits the reproductive cycle in females without adversely affecting male fertility.”
It seems that further research is needed into this specific area. Metabolism is closely linked in evolutionary terms to our survival, and their is no denying the fact that males and females play very different roles in that regard. It is logical therefore that IF could trigger a different physiological response between the genders.
Intermittent fasting is generally considered to be suitable for most people, but it would be recommended that you speak to your health professional before starting a drastically different eating plan. This is especially true if you are diabetic, suffering with depression, pregnant or nursing.
I am certainly ready to give IF a try. I feel that it is a lifestyle similar to what we would have been subjected to in our distant past. Some humans do have a tendency to overeat, and I also believe that this has roots in our ancestry – with overeating in times of feast being a sensible tactic to help us survive the times of famine. Carrying extra weight between feasts would have enabled us to reproduce and nurture our young.
That is no longer necessary though, and I would like to see how the reduction in calories impacts not only my waistline, but also my cognitive function. Learning and memory are thought to improve with a reduced calorific intake, as well as the use of ketones over glucose as energy.
This is in addition to the unseen benefits that may be taking place, on chronic disease. As always, we are not able to make a concrete link between the cause and effect found in these trials, but it is promising for sure, as the quote below demonstrates.
“We generally like to see not only an initial discovery in a trial but we like to see confirmatory trials to be sure that in the broadest kind of sense, in the general population that these findings are going to be applicable. I do believe fasting to be a very effective mechanism. They are pieces of a puzzle, that puzzle is not fully revealed yet, the picture isn’t clear yet but there’s enough of the picture clear. I think we can be really excited that there is some substantial truth here, some substantial data coming forward and something that we can really be hopeful about.”
Dr Lawrence Piro, a cancer specialist at The Angeles Clinic and Research Institute.
What do you think? Are you a regular faster? Or does this just sound like another fad to you? We would love to hear your thoughts.
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