Unless you live under a rock or have been hiding in the gym you may have noticed that intermittent fasting (IF) has gained a lot of media attention recently. The media has glorified this new diet trend by claiming it’s the ‘key to weight loss’ or ‘the solution to anti-ageing’.
What we need is a reality check and the answers to these questions. Are we all getting way too over excited by these dramatic promises? Is the research really there to support this trend? Is this something we should be trying out for ourselves?
What is IF?
Intermittent fasting is a term which is used for eating patterns which restrict your eating time or calorie intake over a set time period. There are a variety of ways to intermittent fast. It could be limiting the hours in the day you eat (usually to 8-hours a day), the number of calories on set days of the week (often 60% less than normal) or simply skipping food altogether on certain days. This couldn’t sound any less appealing so far, but let’s look at some of the reasons it’s risen to fame.
IF and Disease Risk:
Some short term studies have suggested that IF has shown improvements in insulin resistance. In turn this can help to reduce your risk of type 2 diabetes and cardiovascular disease. The improvements have been linked to an increase in stress signal response and mitochondrial health which help to repair your DNA. You might be confused as to where DNA comes into this. But in simple terms damaged DNA can impair how they perform their roles in the body.
IF and Ageing:
Some research has suggested that IF can contribute to a small increase in the SIRT3 gene. What does that mean? Well this gene helps to protect you against oxidative stress (when the body becomes unable to control free-radicals). Before you get over excited you should be aware though that much of the research surrounding SIRT3 and IF has been done on animals and so can be difficult to apply to us humans. There have also been studies to suggest that IF can reduce IGF-1 (a hormone which contributes to ageing) and can therefore prolong longevity. We do need some more research though to draw these conclusions for certain.
IF and Weight Loss:
Like so many dietary trends… one of the key areas which has attracted so much media attention to IF is weight loss. Some short term studies have shown that IF may induce moderate weight loss but we have to assess the quality of these studies (sorry science is just never as straight forward as we’d like). The biggest issue here is that the majority of the studies are short-term which means we don’t know how they pan out over a longer time period. Like many fad diets, weight loss may occur in the early stages but the biggest issue is how sustainable the diet/ lifestyle is and will the weight pile back on when you return to your usual habits?
IF and Restriction:
As mentioned the studies surrounding IF are short-term. This makes it difficult to assess the risk that this type of restriction may have on our future eating habits. As a result, many nutritionists would be hesitant to promote IF as a way of eating. The restriction puts you at risk of overeating and binge eating once the pattern becomes less sustainable. However, like everything there are certainly the anomalies and so you may have a friend or a relative who is thriving on IF but you shouldn’t base your decisions on the experience of those around you (or those you follow on social either).
IF and Long-Term Health:
The research is not strong enough to promote this diet for long-term health. Some studies suggest that the dramatic rollercoaster of increases and decreases of human-growth-hormone (in response to IF) may promote long term health issues and (once again) more studies are needed to conclude this.
Overall, whilst IF may prove beneficial for some, the research is not strong enough to support IF over a long period of time and therefore you should speak to a health professional before trying it out.
Longo, V. D., & Mattson, M. P. (2014). Fasting: molecular mechanisms and clinical applications. Cell metabolism, 19(2), 181-192.
Wegman, M. P., Guo, M. H., Bennion, D. M., Shankar, M. N., Chrzanowski, S. M., Goldberg, L. A., … & Anton, S. D. (2015). Practicality of intermittent fasting in humans and its effect on oxidative stress and genes related to aging and metabolism. Rejuvenation research, 18(2), 162-172.
Mattson, M. P., Longo, V. D., & Harvie, M. (2017). Impact of intermittent fasting on health and disease processes. Ageing research reviews, 39, 46-58.
Horne, B. D., Muhlestein, J. B., & Anderson, J. L. (2015). Health effects of intermittent fasting: hormesis or harm? A systematic review. The American journal of clinical nutrition, 102(2), 464-470.